US3673286A

US3673286A - Method of making propellant body having voids throughout body

Info

Publication number: US3673286A
Application number: US4052A
Authority: US
Inventors: Robert F Remaly; William A Abel
Original assignee: Victor Comptometer Corp
Current assignee: Daisy Manufacturing Co Inc
Priority date: 1970-01-19
Filing date: 1970-01-19
Publication date: 1972-06-27
Anticipated expiration: 1989-06-27
Also published as: CA928080A; GB1341209A

Abstract

A propellant for caseless ammunition for firearms and processes of manufacture thereof comprising at least partial dissolving of commercial nitrocellulose, wetted with a predetermined amount of a volatile wetting agent such as ethyl alcohol, by a solvent, such as acetone, to form a wet doughy mass of propellant, uniformly mixing a predetermined amount and size of removable filler particles, such as 30 percent coarse and 70 percent fine potassium nitrate particles in the wet doughy mass of propellant, forming a propellant body, and removing the wetting agent, solvent, and potassium nitrate particles to form voids throughout the propellant body.

Description

Elnited States Patent Remaly et a1.

[ June 27, 1972 METHOD OF MAKING PROPELLANT BODY HAVING VOIDS THROUGHOUT BODY Inventors: Robert F. Remaly, Olympia Fields; William A. Abel, Joliet, both of Ill.

Victor Comptometer Chicago, 111.

Filed: Jan. 19, 1970 Appl. No.: 4,052

Assignee: Corporation,

Alexander 3,353,438 11/1967 Scanlon et al. ..264/3 Primary Examiner-Carl D. Quarforth Assistant ExaminerStephen .1. Lechert, Jr. Attorney-Bruce G. Klass [57] ABSTRACT A propellant for caseless ammunition for firearms and processes of manufacture thereof comprising at least partial dissolving of commercial nitrocellulose, wetted with a predetermined amount of a volatile wetting agent such as ethyl alcohol, by a solvent, such as acetone, to form a wet doughy mass of propellant, uniformly mixing a predetermined amount and size of removable filler particles, such as 30 percent coarse and 70 percent fine potassium nitrate particles in the wet doughy mass of propellant, forming a propellant body, and removing the wetting agent, solvent, and potassium nitrate particles to form voids throughout the propellant body 22 Claims, No Drawings METHOD OF MAKING PROPELLANT BODY HAVING VOIDS TWOUGHOUT BODY BACKGROUND OF INVENTION l-leretofore, commercially available low energy propellant for caseless ammunition of recently developed air ignition firearm systems has been made by a process utilizing dry nitrocellulose base material as described in copending applications, Ser. No. 473,556 filed July 7, 1965, for Air Operated Projectile Firing Apparatus and Ser. No. 785,317 filed Dec. 19, 1968, for Caseless Ammunition and Propellant and Method of Making Same. From a safety standpoint, it is preferable to utilize wet" nitrocellulose and this invention involves the manufacture of air ignition system propellant from wet" nitrocellulose. Actually, United States Govermental agency regulations require that various forms of nitrocellulose be transported wet with specified amounts of volatile wetting agents such as alcohol. In practice, most commercial wet nitrocellulose is wetted by a mixture of alcohol and water. Tests indicate that, at the time of utilization of commercial shipments of nitrocellulose, the amounts of alcohol and water vary substantially from shipment to shipment. Among the various requirements in the successful manufacture of a low energy propellant for air ignition system firearm caseless ammunition, the one dominant requirement is consistency of performance of the propellant as measured primarily by muzzle velocity of the caseless ammunition projectile, the maximum breech pressures generated, and the rate of burning of the propellant as measured by the time to obtain maximum breech pressure. Thus, heretofore, the use of wet nitrocellulose in the manufacturing process was considered to introduce too many variables to permit consistent manufacture of a propellant producing the desired results. However, the present invention enables the consistent manufacture of propellant having a controlled density and a controlled surface area.

SUMMARY OF INVENTION The invention herein disclosed resides in the manufacture of a porous propellant for caseless ammunition for firearms, presently primarily of small caliber, and more particularly for air ignition system firearms, by use of a wet nitrocellulose base material. In general, the process comprises at least partially dissolving a known quantity of wet nitrocellulose by addition of a known quantity of nitrocellulose solvent to form a wet doughy mass of nitrocellulose, mixing a known quantity and quality of filler material in uniform dispersion throughout the wet doughy mass of nitrocellulose, forming a body of propellant from the wet doughy mass of nitrocellulose and filler material, and then removing the filler material and the solvent and the wetting agent to form voids in the propellant body providing a predetermined degree of porosity. It is to be understood that all references to parts of ingredients in the various formulations is parts by weight.

DETAILED DESCRIPTION I. Manufacturing Processes Method A: The presently preferred method of manufacturing the caseless ammunition by wet processing comprises, in general, the steps of:

l. Grinding filler material (the presently preferred filler material being solid particles of potassium nitrate) to obtain a coarse and a fine particle size (the presently preferred sizes for coarse particles being through size 30 sieve and on size 70 sieve, i.e. distributed between 0.590 mm and 0.210 mm, and for fine particles being through size 200 sieve, i.e. less than 0.074 mm.) (The above sieve sizes and all sieve sizes hereinafter are U.S. Standard sieve sizes).

2. Blending the coarse and the fine size particles of filler material to obtain a filler material particle blend having predetermined amounts of each size (the presently preferred ratio being 70 percent fine 30 percent coarse).

3. Dehydrafing water wet nitrocellulose (13.2 13.5 percent N) by passing alcohol through the nitrocellulose under pressure to obtain alcohol wet nitrocellulose having a predetermined quantity of alcohol (the presently preferred ratio being 25 parts alcohol to parts NC).

4. At least partially colloiding the alcohol wet nitrocellulose by mixing predetermined amounts of the alcohol wet nitrocellulose, with the nitrocellulose solvent and adding the filler material blend to obtain a wet doughy mass of at least partially colloided nitrocellulose and blended filler material uniformly dispersed throughout (the presently preferred mixture being 100 parts dry NC wet with 25 parts alcohol, 72 parts acetone solvent, 1.5 parts diphenylamine stabilizer, and parts of a 70 percent fine30 percent coarse particle blend of potassium nitrate filler).

5. Forming the dough into individual propellant forms by any conventional method and apparatus such as by molding or extruding and attaching each individual form to an associated projectile.

6. At least partially setting up the propellant form on the associated projectile (it is presently preferred to keep the propellant at room temperature for approximately four hours).

7. Subsequently leaching out the filler material by boiling in water (the presently preferred leaching step comprises repeated immersion of the propellant in boiling water 100 C.) for at least two hour intervals followed by cold water rinses between boiling periods until the filler material and the solvent have been substantially removed).

8. Drying the leached propellant (in the presently preferred form the propellant is subject to hot air, 50 C., for approximately 24 hours).

Method B: An alternative method of manufacturing caseless ammunition by wet processing comprises the steps of:

l. Placing a known weight of NC having a total liquid content of water and alcohol of approximately 25.0 percent of the weight of NC into a plastic mixing bag.

2. Adding a predetermined size and weight of KNO particles.

3. Mixing the KNO particles and the wet NC until obtaining a homogeneous mixture having no visible lumps or segregation of constituents.

4. Separately preparing a solution of acetone in the amount of 0.94 ml (0.744 grams) per gram of the volatile-free NC and diphenylamine in an amount of approximately 1.5 percent of the volatile-free NC.

5. Adding the acetone and diphenylamine solution to the NC KNO particle mixture in the mixing bag, sealing the bag, and kneading the mixture for approximately one-half hour or until a uniform dough-like mixture is obtained.

6. Forming the dough-like mixture into a rough cylindrical charge shaped to fit an extruder cylinder associated with a mold or die cavity for .22 caliber caseless ammunition.

7. Placing a 29 z 1 grain .22 caliber projectile of the type described in copending application, Ser. No. 782,291, filed Dec. 9, 1968, for Air Ignition System Ammunition in one end of the cylinder die cavity.

8. Unsealing the bag and quickly placing the dough-like mixture into the extruder cylinder.

9. Extmding some of the doughlike mixture into the die cavity to form a body of propellant of desired size and shape attached to the rear of the projectile.

l0. Removing the projectile and green" propellant from the die cavity and air drying the propellant.

ll. Removing the liquids and the KNO from the formed propellant body by boiling in distilled water for eight hours and changing the water every two hours.

ll. Ingredients A. Propellant Base Material: The base material for the propellant is commercially available nitrocellulose having a relatively high degree of nitration of between 12.5 and 13.5%

N. Nitrocellulose formed from either cotton linters or wood pulp is satisfactory and it is contemplated that other types of base materials may also be employed as outlined in copending application, Ser. No. 785,317 filed Dec. 19, 1968, for Caseless Ammunition and Propellant and Method of Making Same.

B. Wetting Agent: The term wetting agent" as used herein refers to the alcohol-water liquid content of the nitrocellulose utilized in the process and is not intended to be limited to the definition of the term as applied in general catalytic type chemical reactions although the wetting agent does appear to have some of the characteristics of such wetting agents. Since commercially available nitrocellulose is normally wetted with alcohol and/or water in order to be safely handled and transported, the wetting agent for the nitrocellulose may most advantageously be alcohol of the type used with the commercially available nitrocellulose. As will be understood by those skilled in the art, some water must be used with alcohol to prevent the alcohol from dissolving the nitrocellulose. Ethyl alcohol is preferred but other alcohols such as isopropyl a1- cohol may be used. While from a safety standpoint the amount of alcohol (and/or other liquids such as water) may vary within certain limits, it appears that commercially available wet nitrocellulose usually has between 15 and 40 percent alcohol and/or water wetting agent volatiles associated therewith. In any event in the wet manufacturing process, it is necessary to use a known amount of nitrocellulose and a known amount of wetting agent. Therefore, it is necessary to process the commercially available nitrocellulose to provide a predetermined amount of wetting agent, the presently preferred amount being 25 parts wetting agent to 100 parts nitrocellulose. It is believed that this ratio may be varied i 5 parts wetting agent without seriously affecting the ballistic performance of the porous propellant; however, it is preferable to standardize the constituents and the amounts of the wetting agent for any given formulation. One method of standardization is to measure and analyze the commercial wetting agent and add or subtract as necessary to achieve the desired amounts and constituents. The presently preferred in plant method is to process commercial water wet nitrocellulose in a standard dehydration press by forcing alcohol through the water wet nitrocellulose under pressure until the water is removed and the desired amount of alcohol is added.

C. Nitrocellulose Solvent: The basic requirements of the solvent are that it be substantially inert to the filler material and sufficiently dissolve the nitrocellulose to form a workable wet doughy mass. The term dissolve," as used herein, is intended to encompass conditions variously referred to in the art as gelatinizing, colloiding, etc. Since the solvent is subsequently removed and much of it may be lost in the manufacturing process, it is highly desirable to reduce the quantity required. One of the advantages of wet processing is that the amount of solvent has been reduced as compared with the amount of solvent required for dry processing. For example, in the presently preferred form of manufacturing an equivalent propellant by dry processing 95 parts of acetone solvent are required per 100 parts of nitrocellulose whereas in the presently preferred form of wet processing only 72 parts of acetone solvent are required. Furthermore, the amount of solvent tends to remain constant regardless of increases in the amount of filler material used which is contrary to experience with dry processing where increases in the amount of filler required additional amounts of solvent. It is believed that the alcohol wetting agent, while being miscible with acetone and insoluble to the nitrocellulose, acts to promote solvent action by improving the wet ability of the nitrocellulose and increasing accessibility of the nitrocellulose to the solvent and, hence, the rate of dissolution of the nitrocellulose. The reduction in the amount of solvent required is also important in relationship to shrinkage of the propellant body. Since the greatest portion of the shrinkage occurs during the solvent removal stage of the propellant manufacture, reduction of solvent will reduce the amount of shrinkage.

D. Filler Material: It is contemplated that the tiller material may be provided by solid particles of materials other than the preferred potassium nitrate such as other salts like barium nitrate or sugar or the like. The amount of filler material may be varied depending upon the desired degree of propellant porosity. While it is contemplated that useful results may be obtained by using filler material in amounts of between 100 to 400 parts per 100 parts of nitrocellulose, the presently preferred ratio is 180 parts of filler material per 100 parts of nitrocellulose. While the exact reason is unknown, the same degree of porosity can be obtained in wet processing with a substantially lesser amount of filler material than required in dry processing. For example, the preferred wet processing filler material ratio of 180:100 is considerably less than the preferred dry processing filler material ratio of 239: 100. Thus, in wet processing of nitrocellulose there is a substantial decrease in the amount of filler material required and, hence, the cost of manufacture of the propellant.

Tests indicate that the most satisfactory results are obtained by using a blend of coarse and fine size filler material particles. While the reason why such a blend produces better results is not exactly known, it is believed that the coarse particles produce a sufficient number of large size voids in the propellant to insure good ignition characteristics and that the fine particles produce sufficient porosity to provide good burning characteristics while maintaining a relatively high charge weight per given volume of propellant. The presently preferred ratio of 70 percent fine and 30 percent coarse is approximately midway between what appears to be the most useful range of 60 to percent fine and 40 to 20 percent coarse.

Another factor in wet processing is the action of an alcoholwater wetting agent on the filler material. Tests indicate that a small amount, eg 4 or 5 percent, of the potassium nitrate may be dissolved by the alcohol-water mixture. This dissolution probably affects all particle sizes of potassium nitrate but the smallest particle size would likely be completely dissolved. In any event, all particle sizes are probably reduced in the mixture of solvent, wetting agent, filler, and nitrocellulose. However, after the propellant is formed and as the wetting agentsolvent volatiles are being removed, the potassium nitrate in solution probably precipitates on the remaining potassium nitrate particles to increase the size of the particles and ultimately the size of the voids.

E. Stabilizer and Additives: Small amounts of diphenylamine stabilizer are used in all formulations in accordance with long established practice in the propellant art. While none of the various ballistic controlling additives have been utilized in the various formulations herein disclosed, it is contemplated that such additives may be used if necessary or desirable.

Ill. Formulations EXAMPLE 1 The presently preferred formulation is as follows:

parts nitrocellulose 25 parts wetting agent (alcohol) 72 parts solvent (acetone) parts filler material (30 percent coarse and 70 percent fine potassium nitrate particles) 1.4 parts stabilizer (diphenylamine) The coarse particles are between 0.59 mm and 0.21 mm (30 and 70 sieve). The fine particles are less than 0.074 mm (200 sieve).

Physical characteristics of propellant manufactured as in method A by use of this formulation are: charge weights 54 to 59 mg, density 0.560 to 0.625 g/cc, and Shore D hardness 40 to 60. Ballistic characteristics of such propellant are: average velocity at 75 F. 1,095 fps to 1,140 fps, at 98 percent relative humidity 1,085 fps to 1,136 fps; average maximum chamber pressure at 75 F. 22,000 to 30,000 psi, at 0 F. 16,600 to 26,000 psi, at 98 percent relative humidity 16,700 to 22,300

EXAMPLE 2 100 parts nitrocellulose 33 parts wetting agent (28 parts alcohol and 5 parts water) 72 parts solvent (acetone) V 200 parts filler material (50 percent coarse 0.149 mm 100 sieve to 0.125 mm 120 sieve and 50 percent fine 0.074 mm 200 sieve to 0.044 mm 325 sieve potassium nitrate particles) 1.5 parts stabilizer (diphenylamine) Various propellant batches made from this formulation by method B resulted in an average muzzle velocity of 1,149 i 9 feet per second and an average maximum chamber pressure of 28,700 2 1,500 psi when fired from a test gun at 75 F. and 50 percent relative humidity. At low temperature (i.e. F.) there was a velocity decrease of less than 50 feet per second and at high humidity (i.e. 97 i 2 percent relative humidity) there was less than 40 feet per second velocity loss.

With a 57 i 1 mg charge of the formulation of Example 2, changes in the percentage of fine particles produced the following results:

% fines coarse velocity fps Example 3 0 100 1103 Example 4 25 75 1119 Example 50 50 l 149 By way of comparison, with a 57 I 1 mg charge of the formulation of Example 2 processed with 250 instead of 200 parts potassium nitrate, changes in the percentage of fines produced the following results:

Charges of similar weight of the propellant of Example 2 processed with 200 parts filler comprising particles of between 0.149 mm (100 sieve) and 0.125 mm 120 sieve) produced an average velocity of 1,103 feet per second and an average chamber pressure of 13,900 psi.

EXAMPLE 1 1 Other charges of similar weight of the propellant of Example 2 processed with 200 parts filler comprising 50 percent coarse particles of between 0.149 mm (100 sieve) and 0.125 mm (120 sieve) and 50 percent fine particles of between 0.074 mm (200 sieve) and 0.0014 mm (325 sieve) produced only a slightly higher average velocity of only 1,151 feet per second with much higher average chamber pressure of 27,500 psi.

EXAMPLE 12 100 parts nitrocellulose 32 parts wetting agent( 30 parts alochol 2 parts water) 72 parts solvent (acetone) 1 part diphenylamine stabilizer 146 parts coarse filler (potassium nitrate particles 0.125 to 0.149 mm) (120 to 100 sieve) 49 parts fine filler (potassium nitrate particles 0.044 to 0.074 mm) (325 to 200 sieve) Tests show that a charge of this formulation weighing 57 mg will produce a muzzle velocity of approximately 1 ,120 fps with a maximum chamber pressure of approximately 25,000 psi. Comparative tests indicate an approximate straight line relationship between charge weight and velocity as well as pressure.

1V. Physical Characteristics of Caseless Round Propellant and Projectile The caseless ammunition for which the propellants of this invention have been developed comprises a 29 grain .22 caliber projectile of the type described in the aforementioned copending applications or in copending application, Ser. No- 782,291 filed Dec. 9, 1968, for Air lgnition System Ammunition. The ammunition has a maximum outside diameter of approximately 0.224 inch with a length of approximately 0.540 inch. The design length of the propellant portion is approximately 0.245 inch and the design diameter is the same as the projectile diameter of approximately 0.224 inch. The design volume is approximately 0.00915 inch", there being an attachment post extending rearwardly of the projectile. The actual volume of propellant varies somewhat from round to round due to production variations such as shrinkage but the average volume is approximately 0.0064 inch.

V. The Propellant Parameters While the propellant is designed for use in a .22 caliber air ignition system firearm, as manufactured by Daisy/Heddon. Division of Victor Comptometer Corporation, it may be modified for use with larger caliber firearms or for other uses as necessary or desirable. 1n the aforementioned .22 caliber system, the propellant is designed to provide a muzzle velocity of approximately between 1,100 and 1,200 feet per second and chamber pressure of approximately between 20,000 psi and 30,000 psi under normal conditions, it being understood that high temperature-high humidity and low temperature conditions have an effect on these parameters. In general, the propellant parameters producing the desired results include a charge weight of approximately between 45 and 65 mg, a Shore D hardness of approximately between 40 and 60, and a density of approximately between 0.500 and 0.625 g/cc. The following examples further illustrate the effect of variations in the propellant parameters of nitrocellulose-filler ratio and par- 60 ticle size:

A. FORMULATIONS [Examples 13-24] NC/ Wetting agent,

KNO3, ethyl alcohol Adetone g. and water, g. DPA, g. g. Particle sizes 100/180 1.5 87 through 100 on 120 seive, 70% through 140 on 200 sieve. 100/200 25 1.5 01. 5 through 100 on 120 sieve, 65% through 200 on 270 sieve. 100/200 25 1. 5 01.6 through 100 on 120 sieve, through 140 on 200 sieve. 100/200 25 1.2 82 100% through 120 on 140 sieve. 100/200 25 1.2 81. 5 100% through 140 on 200 sieve. 100/200 25 1. 2 81.5 100% through 100 on 120 sieve. 100/220 25 1. 5 01. 5 50% through 100 on 120 sieve, 50% through 140 on 200 sieve. 100/220 25 1.0 85 50% on sieve, 50% through 200 sieve. 100/220 25 1.0 through 100 on sieve. 100/220 25 1.0 85 63.7% on 70 sieve, 18.8% through 70 on 100 sieve, 0.5% through 100 on 120 sieve, 4.5% through 120 on sieve, 6.5% through 140 on 200 sieve. 100/240 25 1. 5 01.5 70% through 100 on 120 sieve, 30% through 140 on 200 sieve. 24 100/240 25 1. 5 02. 5 58.5% on 70 sieve, 17.3% through 70 on 100 sieve, 5.0% through 100 on 120 sieve, 4% through 120 on 140 sieve, 6% through 140 on 200 sieve 8.3% through 200 sieve.

The wetting agent of Examples 13-24 is approximately 22 parts alcohol and 3 parts water.

Illxmnnlus 13-24] Vnlncl'r1:: Bulk Time to ity, sun, (Ilmruv. vlnnsity, mux. [)l'csl'ixmnpln Nu. 1.11.5. psi. \vt., mg. gmsjcc. sum, in. sec

1, 175 24, (364 no, u 524 45 1, 114 28, 000 58. .506 41 1, 133 25, 333 56. 0 480 (i2 1, 140 17, 331 65. 0 556 .30 1,153 16,000 63. 0 550 43 1,177 18,665 5 .554 58 1,070 1, 344 51. 5 440 .80 1, 158 18, 664 62. 0 .540 .46 1, 111 12,000 63. 5 554 61 1,056 8, 665 60.0 .523 41 1,074 21, 341. 40. 5 432 56 001 4, 366 50.0 436 46 In general, these results indicate that a high percentage of coarse particles such as found in Examples 22 and 24 substantially reduce the resultant velocities and pressures. A comparison of Examples l3, 14, 15, 16, 17, 19 and 23 indicates that increasing percentages of fine particles are advantageous up to at least 70 percent but that less advantageous results are obtained with 100 percent. These and other results indicate that 60 to 80 percent fine particles is probably the most advantageous particle size range. The differences in charge weight are primarily due to variations in porosity of the propellant. The bulk density is an approximation based upon the volume of the propellant forming die. It is to be understood that many of the results herein disclosed are based upon limited testing and have not been substantiated to an exact degree by quantitative or qualitative testing. However, it is believed that these results are generally indicative of the results to be expected with the formulations disclosed. Unless otherwise specified, the results given are for similarly processed ammunition fired under similar conditions from the same test apparatus.

We claim:

1. The process of manufacturing propellant for caseless ammunition comprising the steps of:

l. wetting nitrocellulose with a predetermined amount of substantially inert volatile wetting agent;

2. at least partially dissolving the wet nitrocellulose by mixing with a volatile nitrocellulose solvent inert and miscible with the wetting agent to form a wet doughy mass of nitrocellulose, solvent, and wetting agent;

3. uniformly dispersing a removable filler throughout the wet doughy mass;

4. forming the wet doughy mass into a propellant body with the removable filler uniformly dispersed throughout;

5. removing the wetting agent and solvent and removable filler without substantially changing the form of the propellant body and thereby forming voids throughout the propellant body; and

6. drying the propellant body to provide a hard porous qriopellant for caseless ammunition. e invention as defined 1n clarm 1 and wherein the who by weight of wetting agent to nitrocellulose is between 1:5 and 2:5.

3. The invention as defined in claim 2 and wherein the wetting agent consists of alcohol and water.

4. The invention as defined in claim 3 and wherein the ratio by weight of alcohol to water is between 20:3 and 30:2.

5. The invention as defined in claim 2 and wherein the wetting agent consists primarily of alcohol.

6. The invention as defined in claim 1 and wherein there is between approximately 25 and 33 parts by weight wetting agent per 100 parts by weight nitrocellulose.

7. The invention as defined in claim 1 and wherein there is approximately 25 parts by weight wetting agent per 100 parts by weight nitrocellulose.

8. The invention as defined in claim 1 and wherein the amount of solvent is in the ratio of approximately between and 120 parts by weight solvent to 100 parts by weight nitrocellulose.

9. The invention as defined in claim 8 and wherein the amount is less than approximately 100 parts by weight solvent to 100 parts by weight nitrocellulose.

10. The invention as defined in claim 9 and wherein the amount is less than approximately parts by weight solvent to 100 parts by weight nitrocellulose.

11. The invention as defined in claim 1 wherein the solvent is acetone in the ratio of approximately 70 75 parts by weight acetone to 100 parts by weight nitrocellulose.

12. The invention as defined in claim 1 and wherein the ratio of removable filler to nitrocellulose is less than 2 to l.

' 13. The invention as defined in claim 12 and wherein the ratio is between 1.7 to l and 1.9 to l.

14. The invention as defined in claim 13 and wherein the ratio is 1.8 to l.

15. The invention as defined in claim 1 and wherein the removable filler is a blend of coarse and fine size particles.

16. The invention as defined in claim 15 and wherein the coarse particle size is distributed between approximately 0.59 mm and 0.21 mm.

17. The invention as defined in claim 16 and wherein the fine particle size is less than approximately 0.074 mm.

18. The invention as defined in claim 17 and wherein the blend consists of approximately 30 percent coarse particles and 70 percent fine particles.

19. The invention as defined in claim 15 wherein the blend consists of approximately 20 to 40 percent coarse particles and to 60 percent fine particles.

20. The invention as defined in claim 19 and wherein the blend is approximately 30 percent coarse particles and 70 percent fine particles.

21. The invention as defined in claim 1 and wherein the volatile solvent and wetting agent dissolve some of the filler in the wet doughy mass, and wherein the volatile solvent and wetting agent are removed from the propellant before all of the filler and some of the dissolved filler is precipitated out in the propellant during removal of the volatile solvent and wetting agent.

22. The invention as defined in claim 21 and wherein after forming the propellant body isfirst air dried to remove some of the volatile solvent and wetting agent, and then the propellant body is placed in boiling water to remove the filler and any remaining volatile solvent and wetting agent.

Claims

2. The invention as defined in claim 1 and wherein the ratio by weight of wetting agent to nitrocellulose is between 1:5 and 2:5.
2. at least partially dissolving the wet nitrocellulose by mixing with a volatile nitrocellulose solvent inert and miscible with the wetting agent to form a wet doughy mass of nitrocellulose, solvent, and wetting agent;
3. uniformly dispersing a removable filler throughout the wet doughy mass;
3. The invention as defined in claim 2 and wherein the wetting agent consists of alcohol and water.
4. The invention as defined in claim 3 and wherein the ratio by weight of alcohol to water is between 20:3 and 30:2.
4. forming the wet doughy mass into a propellant body with the removable filler uniformly dispersed throughout;
5. removing the wetting agent and solvent and removable filler without substantially changing the form of the propellant body and thereby forming voids throughout the propellant body; and
5. The invention as defined in claim 2 and wherein the wetting agent consists primarily of alcohol.
6. The invention as defined in claim 1 and wherein there is between approximately 25 and 33 parts by weight wetting agent per 100 parts by weight nitrocellulose.
6. drying the propellant body to provide a hard porous propellant for caseless ammunition.
7. The invention as defined in claim 1 and wherein there is approximately 25 parts by weight wetting agent per 100 parts by weight nitrocellulose.
8. The invention as defined in claim 1 and wherein the amount of solvent is in the ratio of approximately between 70 and 120 parts by weight solvent to 100 parts by weight nitrocellulose.
9. The invention as defined in claim 8 and wherein the amount is less than approximately 100 parts by weight solvent to 100 parts by weight nitrocellulose.
10. The invention as defined in claim 9 and wherein the amount is less than approximately 75 parts by weight solvent to 100 parts by weight nitrocellulose.
11. The invention as defined in claim 1 wherein the solvent is acetone in the ratio of approximately 70 - 75 parts by weight acetone to 100 parts by weight nitrocellulose.
12. The invention as defined in claim 1 and wherein the ratio of removable filler to nitrocellulose is less than 2 to 1.
13. The invention as defined in claim 12 and wherein the ratio is between 1.7 to 1 and 1.9 to 1.
14. The invention as defined in claim 13 and wherein the ratio is 1.8 to 1.
15. The invention as defined in claim 1 and wherein the removable filler is a blend of coarse and fine size particles.
16. The invention as defined in claim 15 and wherein the coarse particle size is distributed between approximately 0.59 mm and 0.21 mm.
17. The invention as defined in claim 16 and wherein the fine particle size is less than approximately 0.074 mm.
18. The invention as defined in claim 17 and wherein the blend consists of approximately 30 percent coarse particles and 70 percent fine particles.
19. The invention as defined in claim 15 wherein the blend consists of approximately 20 to 40 percent coarse particles and 80 to 60 percent fine particles.
20. The invention as defined in claim 19 and wherein the blend is approximately 30 percent coarse particles and 70 percent fine particles.
21. The invention as defined in claim 1 and wherein the volatile solvent and wetting agent dissolve some of the filler in the wet doughy mass, and wherein the volatile solvent and wetting agent are removed from the propellant before all of the filler and some of the dissolved filler is precipitated out in the propellant during removal of the volatile solvent and wetting agent.
22. The invention as defined in claim 21 and wherein after forming the propellant body is first air dried to remove some of the volatile solvent and wetting agent, and then the propellant body is placed in boiling water to remove the filler and any remaining volatile solvent and wetting agent.