View Full Version : What would cause this kind of compensator damage?
netchemica
05-03-13, 16:20
I took my rifle to the range the other day to sight in my Leupold Mark IV. I took 100 rounds I bought from Freedom Munitions back in October. They are 62gr m855. The specs for my rifle are at the bottom.
I ended up getting a 18" group at 100 yards, which was very disappointing. I blamed it on me never shooting past 25yards, shitty trigger, "generic" barrel, and cheap bullets.
Then I saw this when I got home (click for bigger image):
http://i.imgur.com/4R4fn1hl.jpg (http://imgur.com/4R4fn1h.jpg)
http://i.imgur.com/fjIZ47Cl.jpg (http://imgur.com/fjIZ47C.jpg)
http://i.imgur.com/shHBqgdl.jpg (http://imgur.com/shHBqgd.jpg)
I dropped my bore sighter in there and didn't see the laser hit any part of the compensator and it had equal glare on each side. I took it off to check the threads, which were fine. The comp was torqued properly. I have over 6,000 rounds through this rifle that have ever resulted in anything like this.
I have fired several hundred rounds from this "batch" before this, the only thing I changed was using Frog Lube.
My rifle:
LMT upper receiver group, 16" Carbine Length w/ government profile, 1:7 twist
Bravo Company BCG
JP Bennie Cooley
Rainier Arms lower receiver
I contacted Freedom Munitions about this and this was their reply:
We have not had any feed back about this being an issue, that is a mil-spec bullet (M855) and have not heard about any issues from any of the sources we purchase from?
I also contacted JP Enterprises about this and their response was much friendlier and thorough.
Thanks for choosing our products! On the brake, what you had there was a jacket separation at some point. In other words, a piece of jacket separated from a bullet and impacted the brake on the way out. A piece of jacket is all it takes to create a big divot or crater in the baffle plate of a muzzle brake. It happens. So we have what we call the “bailout program”. Anytime a part gets ruined for some reason that is not our fault, we’ll sell you another at a big discount, in this case, $35.
Do you guys have any input?
William B.
05-03-13, 16:28
JP's explanation sounds legit to me.
Check the crimp on the rounds. If it's overcrimped, that can contribute to jacket separation.
From the last pic you posted I think I see a hairline crack. It looks like it took a hit from the inside and bulged out (which again would make the explanation from JP sound about right).
Nobody_Special
05-03-13, 18:05
Good offer from JP.
Agreed
Cool by jp. I have never been a fan of freedom munitions.
I am pretty sure you had a bad round. Much like what happens when you have a baffle strike.
netchemica
05-03-13, 19:31
I am pretty sure you had a bad round. Much like what happens when you have a baffle strike.
!A! bad round? One round could cause that. It seems like something that happened several times. Unless the jacket separated at each rifling in the barrel...
Any way to check my rounds to make sure it doesn't happen again?
I seriously doubt it, especially if the company uses pulled bullets. Were they air or collet-pulled? You don't know if or how the jackets may have been stressed.
Several months back, I purchased a thousand pulled M855 projectiles for Re-loading... They were very clean, sized and had very few marks from the process... Everything about the bullets appeared to be A-Ok...
If I hadn't paid attention during the re-loading process, I would never have known There was an empty Jacket in the mix...( no lead core or penetrator) Perhaps that is what happened with the reloads you purchased... They may have received pulled bullets from a scrapped Mil-Spec contract run that didn't meet the requirements... and was not explained what the failure was... hence selling out the very problem ( empty jacketed bullets), which in turn ended up in the cartridge's you shot...
netchemica
05-04-13, 20:18
I emailed JP about how to obtain a replacement compensator around dinner time, and I got a reply about 30 minutes ago!! It's Saturday night!
Talk about awesome. I love these guys, makes me want to build another rifle just so I can use more of their parts.
Did you notice any odd impacts on target, like sideways, keyhole and signs of rounds coming apart in flight?
I'm not trouble shooting just asking.
netchemica
05-04-13, 22:24
Did you notice any odd impacts on target, like sideways, keyhole and signs of rounds coming apart in flight?
I'm not trouble shooting just asking.
I forgot to mention that in my original post. All of my bullet holes were normal... really spread out, but normal.
I dont think that was a jacket separation because the first opening doesn't have any strike marks on it. If the jacket was coming apart the first opening would have taken the most of the impact force. Besides piece of copper jacket has very little mas, I don't think it has enough energy to destroy the break like that.
Or I'm wrong and what could have happened is that the jacket did come a part right out of the barrel, struck the first opening, upset the bullets path enough so that it struck the second opening?
Or another scenario is that the bullet did not stabilize and started to yaw as soon as it got loose from the barrel.
Either way it shows those strikes are from the bullet, there is no way in hell piece of copper jacket could have cracked that break.
See maybe you can take the break off and shoot some paper targets. Look for a keyhole in them. Shoot some really close, like 5 yards or something. Then shoot a known good ammo and compare the bullet holes. They dont have to hit paper sideways to damage the break, if the bullet's pitch or yaw angle is off by couple degrees, it will strike the muzzle device.
Yea, I'm thinking bullet strike. Either the ammo or the comp was off on machining
netchemica
05-05-13, 07:09
Yea, I'm thinking bullet strike. Either the ammo or the comp was off on machining
The compensator was already checked. It is square to the barrel and the ports are lined up properly. This compensator has thousands of rounds through it, the damage would have shown up already if it was machined wrong.
netchemica
05-05-13, 07:18
I dont think that was a jacket separation because the first opening doesn't have any strike marks on it. If the jacket was coming apart the first opening would have taken the most of the impact force. Besides piece of copper jacket has very little mas, I don't think it has enough energy to destroy the break like that.
A blank round can kill a person at close enough range. P=mv, with 3,200fps, you don't need a lot of mass.
Or I'm wrong and what could have happened is that the jacket did come a part right out of the barrel, struck the first opening, upset the bullets path enough so that it struck the second opening?
Very possible, but the first baffle has zero marks on it. Even if the jacket didn't have enough force to damage the baffle, it would have been evident on the erosion from the gun powder. The first baffle wasn't struck at all.
A blank round can kill a person at close enough range. P=mv, with 3,200fps, you don't need a lot of mass.
Has killed at least one Hollywood actor. People don't realize that thr gas has mass as well! Roughly the weight of the powder plus a bit of O2.
A blank round can kill a person at close enough range. P=mv, with 3,200fps, you don't need a lot of mass.
Very possible, but the first baffle has zero marks on it. Even if the jacket didn't have enough force to damage the baffle, it would have been evident on the erosion from the gun powder. The first baffle wasn't struck at all.
I reckon then it's bullet not being stable when leaving the barrel. They are so offset that they strike that break only an inch or so after leaving the barrel.
I think that the reason you didnt see any funny holes on paper is maybe because bullets that struck your break didnt even made it there! I would really like to see you shoot some paper at close range with those loads.
Either way it goes, sucks that you have to go through the ordeal!
I can't see the pics very well since I'm on my phone but is it possible that it's just erosion?
This was taken from BCMs website regarding their comps:
Please note: The combustion gasses exiting the muzzle of a rifle are extremely hot, traveling at extreme velocity, and contains not only burning gasses but solid particles of unburnt powder as well as metals from the projectile. Due to the inherent nature of steel, it is nearly impossible to survive unaffected in this environment when directly exposed. The high temperatures begin to make the steel more malleable, which allows solid particles and pressure waves to deform and erode surfaces upon exit.
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I can't see the pics very well since I'm on my phone but is it possible that it's just erosion?
This was taken from BCMs website regarding their comps:
Please note: The combustion gasses exiting the muzzle of a rifle are extremely hot, traveling at extreme velocity, and contains not only burning gasses but solid particles of unburnt powder as well as metals from the projectile. Due to the inherent nature of steel, it is nearly impossible to survive unaffected in this environment when directly exposed. The high temperatures begin to make the steel more malleable, which allows solid particles and pressure waves to deform and erode surfaces upon exit.
Sent via Tapatalk
Hmmm..the pics are clear...the compensater has taked a hit internaly...however much/some of that damage does look like erosion
Hmmm..the pics are clear...the compensater has taked a hit internaly...however much/some of that damage does look like erosion
Understood. The only pic I could really see was the first one.
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netchemica
05-05-13, 10:23
I reckon then it's bullet not being stable when leaving the barrel. They are so offset that they strike that break only an inch or so after leaving the barrel.
I think that the reason you didnt see any funny holes on paper is maybe because bullets that struck your break didnt even made it there! I would really like to see you shoot some paper at close range with those loads.
Either way it goes, sucks that you have to go through the ordeal!
I'm gonna set up a target at 5 yards and 15 yards right behind it. I'll see what the rounds are doing during their path.
netchemica
05-05-13, 10:25
Understood. The only pic I could really see was the first one.
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There is definite erosion on both baffles, I'm trying to figure out why the second baffle has strong impressions that are not uniform.
I'm gonna set up a target at 5 yards and 15 yards right behind it. I'll see what the rounds are doing during their path.
Awesome thanks, also see if you can take closeup pictures for us.
I dont think that was a jacket separation because the first opening doesn't have any strike marks on it. If the jacket was coming apart the first opening would have taken the most of the impact force.
No. The bullet was likely still somewhat intact and hadn't come apart yet. It made it through the first chamber before getting squirrelly.
diving dave
05-06-13, 11:54
It's happened to me, but in my case it was a bit spookier, as the rifle was a 50BMG.. Had purchased some pulled M33 ball bullets and loaded them up as plinker rounds.. Took a shot at a rock about 400 yards out and felt a pin prick in my off side arm. Had a tiny sliver of copper that barely broke the skin... Took a look inside my brake( rifle is McMillan M88) and clearly saw an impact on the inside, which left a small crack right at the exit hole. Turns out the lead plug at the base of these bullets can come loose. No problem in a machine gun but something with a break can cause issues...I shoot the Hornady amax now.
IndianaBoy
05-06-13, 12:40
Good offer from JP.
I was squadded with John Paul at the Pro-Am last year.
He's a good guy. Very knowledgable as well.
IndianaBoy
05-06-13, 12:43
There is definite erosion on both baffles, I'm trying to figure out why the second baffle has strong impressions that are not uniform.
It takes a little bit of time for a bullet to come apart. It was likely still within the tolerances to fit through the first baffle, but had expanded enough to strike the second.
There is tremendous centripetal force on a bullet. I've blown up 40 grain bullets with my 220 Swift by pushing them too fast before I figured out that heavy for caliber bullets are generally better for most applications. And that's with a 1-12 twist well north of 4000 fps.
1-7, 1-8 or 1-9 @ 3100ish fps is a lot of rotation.
No. The bullet was likely still somewhat intact and hadn't come apart yet. It made it through the first chamber before getting squirrelly.
No. I have a hard time believing that the piece of jacket alone cracked that break. Those are clear bullet strikes.
ETA, I put forward three theories and you singled out just that one. I just dont get it how can you be so sure of your self when there are clearly multiple forces at play here that can produce that kind of effect.
It takes a little bit of time for a bullet to come apart. It was likely still within the tolerances to fit through the first baffle, but had expanded enough to strike the second.
There is tremendous centripetal force on a bullet. I've blown up 40 grain bullets with my 220 Swift by pushing them too fast before I figured out that heavy for caliber bullets are generally better for most applications. And that's with a 1-12 twist well north of 4000 fps.
1-7, 1-8 or 1-9 @ 3100ish fps is a lot of rotation.
I have a hard time with this theory. I ,like you, have blown up a few 52 gr bullets as well. Every single one of them would explode at about 25 yards from the barrel and a clear puff of gray smoke could be visible. In 1-7 twist bullet fired at 3200fps spins at ~310,000 RPM, so yeah that's a lot of spinning.
We just gona have to wait and see those paper targets, if OP ever gets around to it. We should be able to see of it's a jacket separation or tumbling issue.
We just gona have to wait and see those paper targets, if OP ever gets around to it. We should be able to see of it's a jacket separation or tumbling issue.
My guess is that the paper will show nothing, and that it was an isolated bullet. On the other hand... if he's getting 18 inch groups at a hundred?? :eek:
Good Grief... Helen Keller can do better than that.
netchemica
05-06-13, 14:37
My guess is that the paper will show nothing, and that it was an isolated bullet. On the other hand... if he's getting 18 inch groups at a hundred?? :eek:
Good Grief... Helen Keller can do better than that.
I think that the muzzle brake may have started throwing rounds after it was damaged. I've never shot at any serious distance, 99% of it was at 25 yards. I'm usually pretty good with a handgun (I know, different animal). I'm currently the only person at our unit that can qualify with a perfect score consistently. I figured some of that trigger discipline would have transferred over. The stock of the rifle was squared on my shoulder, breathing was calm, and I was using a quality optic (Leupold Mark IV 4.5-14x40).
Failure2Stop
05-06-13, 15:17
Have you tried pulling the brake and seeing what the bare muzzle does?
Dude, stop chewing on your comp.
I think that the muzzle brake may have started throwing rounds after it was damaged. I've never shot at any serious distance, 99% of it was at 25 yards. I'm usually pretty good with a handgun (I know, different animal). I'm currently the only person at our unit that can qualify with a perfect score consistently. I figured some of that trigger discipline would have transferred over. The stock of the rifle was squared on my shoulder, breathing was calm, and I was using a quality optic (Leupold Mark IV 4.5-14x40).
Yeah.. I wasn't saying YOU couldn't shoot... I'm saying there's a problem beyond my original notion of just one bad bullet if they're shooting that bad.
juliomorris
05-06-13, 16:05
Pull the brake check the crown for any burrs and then shoot again at 100. I betting on jacket separation but it could also be a burr destablizing the bullet causing a strike. To me it looks like it is mostly errosion with only one light strike.
netchemica
05-06-13, 16:08
I took the compensator off to get it read to ship it back to JP. The damn thing is 6.15oz, lol. The factory A2 off my BCM rifle is only 2.05, literally a third of the weight.
webscrounger
05-07-13, 01:09
A laser bore sight might not be an accurate test as it's not .223 wide so you don't see a light path the diameter of the bullet. Try running a 556 bore straightness guide down from the muzzle and see if there is interference or non concentric clearance with the comp. Then there's the barrel and comp interface and how true/square they are.
Shoot the rifle without the brake. It won't hurt a thing. Test that way.
netchemica
05-09-13, 08:46
Just to follow up, I was only able to take it to a 25 yard outdoor range. Neither target showed any tumbling or yawing. I still have to find out what accuracy I can squeeze out of it, but I'll save that for when I find some quality rounds.
DIRTMAN556
05-10-13, 20:44
This is one of the reasons why I decided to go ahead with an A2X flash suppressor on my pinned 14.5"
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