Pyrex
04-23-2014, 02:17 PM
It has long been a goal of mine to find a way to shoot full auto for a reasonable price. I have .22 machine guns, however as you might have guessed finding .22 in those quantities as of late is extremely difficult and no longer a viable option. So, I decided whichever caliber I chose needed to be one that had several molds available for, was relatively low velocity at full power to reduce leading and cost (gas checks=nope), and brass was in easy supply. After looking over the options .45 ACP seemed to make the most sense. I have fired many blowback .45 and 9mm sub guns and have never been a fan of them while suppressed. Typically they have excessive port blast/particulate and run quite a bit louder than a closed bolt gas or delayed roller blowback action. I decided I would be doing a gas operated upper for my M16. Quieter suppressed operation, less particulate in my face, and most importantly a slower (adjustable) cyclic rate without increasing bolt mass.
My standard pinking budget load for .45 has always been 5.0gr of Bullseye behind a 230gr LRN. Bullseye runs a little sooty, but always burns completely at that charge. My biggest enemy is going to be leading in the gas system. Of course the first and most important goal is to keep cost down, so I intend to work my way up the loads starting with the cheapest/easiest method possible until I arrive at one that is sufficient.
My first load is a standard 230gr LRN cast from wheel weights, quenched, resized to .452" tumble lubed with LLA, and then allowed to sit for about 4 months. I slugged the barrel and .452" will be the appropriate diameter.
The upper is an RMW Xtreme .45 DI upper 10.5". The cylic rate is a nice slow controllable 850rpm. I have to make my own magazines to fit in an M16 mag well, which I did by drilling the spot welds off the collar on a grease gun magazine and then peeling them off. Using a press I took 0.10" off the width that fits into the mag well, which is just enough to allow clearance, but not enough to smash the follower in the mag body. Then I just had to set the mag feed height and cut a mag catch slot.
I took the gun out for the first time yesterday with a .50 cal can full of LRN. At first I tried some hollow points but it was having non of that. This is going to be hardballer only (which is perfectly fine with me). Once I switched to my cast rounds it started running much better. After fiddling with the mag block and measuring a few things it started to run pretty good. I ran about 200-300 rounds through the gun.
Below is a video of me shooting a 20rd burst through the gun. You can see a pretty substantial cloud of smoke from the cast bullets.
https://www.youtube.com/watch?v=USlk1n-ma8Y
After that burst I was unable to get it to cycle more than 3-4 rounds at a time, and then it locked up completely, I was unable to get it out of battery. Finally I broke it free and then pushed it back into lock and it seized up again (silly me). At first I thought it was the lugs full of junk, but they really didn't look that bad. Once I tore down the BCG I realized what the problem was.
http://i.imgur.com/1oXlZek.jpg?2
http://i.imgur.com/0Uv0wGt.jpg?2
http://i.imgur.com/YJL7cva.jpg?1
The leading was biblical. More so than I have ever seen before. I can't say it's unexpected, but this level of leading was surprising. You can see the rings on the bolt are completely welded together, they would not uncompress at all. The gas ports on the carrier were not that bad, but the bolt channel was dirty. After a pretty extensive cleaning session (completely tore down the whole gun and cleaned every part of the gas system. I can safely say that load is not going to be the one.
http://i.imgur.com/4RIFQ4s.jpg?3
The bore was leaded, but not what I would consider terrible. This isn't a standard pistol, it is a machinegun, so lead is going to collect at higher rates. I let the barrel cool between mags, roughly about 3-4 minutes as to not further exacerbate the leading problem.
So, after the first round of tests I've learned a few things. One thing is I don't want to spend another 2 hours cleaning this upper. I do have some 230gr LRN ran on a master caster with some red carnuba lube which I can try next. If anyone had some suggestions I would really like to hear them. It had been mentioned I should try to run a standard jacketed bullet every 5 round, however I don't think that's going to solve the gas leading problem, that would help the bore for sure. But I'm getting the feeling that maybe trying some Hi-Tek coating may be the best solution to this problem. I believe that will be the next round I work up as a test.
My standard pinking budget load for .45 has always been 5.0gr of Bullseye behind a 230gr LRN. Bullseye runs a little sooty, but always burns completely at that charge. My biggest enemy is going to be leading in the gas system. Of course the first and most important goal is to keep cost down, so I intend to work my way up the loads starting with the cheapest/easiest method possible until I arrive at one that is sufficient.
My first load is a standard 230gr LRN cast from wheel weights, quenched, resized to .452" tumble lubed with LLA, and then allowed to sit for about 4 months. I slugged the barrel and .452" will be the appropriate diameter.
The upper is an RMW Xtreme .45 DI upper 10.5". The cylic rate is a nice slow controllable 850rpm. I have to make my own magazines to fit in an M16 mag well, which I did by drilling the spot welds off the collar on a grease gun magazine and then peeling them off. Using a press I took 0.10" off the width that fits into the mag well, which is just enough to allow clearance, but not enough to smash the follower in the mag body. Then I just had to set the mag feed height and cut a mag catch slot.
I took the gun out for the first time yesterday with a .50 cal can full of LRN. At first I tried some hollow points but it was having non of that. This is going to be hardballer only (which is perfectly fine with me). Once I switched to my cast rounds it started running much better. After fiddling with the mag block and measuring a few things it started to run pretty good. I ran about 200-300 rounds through the gun.
Below is a video of me shooting a 20rd burst through the gun. You can see a pretty substantial cloud of smoke from the cast bullets.
https://www.youtube.com/watch?v=USlk1n-ma8Y
After that burst I was unable to get it to cycle more than 3-4 rounds at a time, and then it locked up completely, I was unable to get it out of battery. Finally I broke it free and then pushed it back into lock and it seized up again (silly me). At first I thought it was the lugs full of junk, but they really didn't look that bad. Once I tore down the BCG I realized what the problem was.
http://i.imgur.com/1oXlZek.jpg?2
http://i.imgur.com/0Uv0wGt.jpg?2
http://i.imgur.com/YJL7cva.jpg?1
The leading was biblical. More so than I have ever seen before. I can't say it's unexpected, but this level of leading was surprising. You can see the rings on the bolt are completely welded together, they would not uncompress at all. The gas ports on the carrier were not that bad, but the bolt channel was dirty. After a pretty extensive cleaning session (completely tore down the whole gun and cleaned every part of the gas system. I can safely say that load is not going to be the one.
http://i.imgur.com/4RIFQ4s.jpg?3
The bore was leaded, but not what I would consider terrible. This isn't a standard pistol, it is a machinegun, so lead is going to collect at higher rates. I let the barrel cool between mags, roughly about 3-4 minutes as to not further exacerbate the leading problem.
So, after the first round of tests I've learned a few things. One thing is I don't want to spend another 2 hours cleaning this upper. I do have some 230gr LRN ran on a master caster with some red carnuba lube which I can try next. If anyone had some suggestions I would really like to hear them. It had been mentioned I should try to run a standard jacketed bullet every 5 round, however I don't think that's going to solve the gas leading problem, that would help the bore for sure. But I'm getting the feeling that maybe trying some Hi-Tek coating may be the best solution to this problem. I believe that will be the next round I work up as a test.