I'm getting brass swiped off of the rim of my empty cases. Do you guys know if these case head swipes I'm getting are normal? Are you guys getting these kind of swipes from your guns? The brass is either being completely flaked off or it will leave a sharp edged burr. The flakes that come off are being found inside the gun.

I have used 168gr FGMM for 40 rounds and 150gr Fusion for 3 rounds (they are in the black shell casing holder in the pictures). Only 2 rounds that I have noticed do not have the swipes (1 of the fusion and 1 of the FGMM). The fusion does not seem to have as bad of swipes.
It is very hard to get this to show up on pictures, so I took a bunch. There is only a total of around 43 rounds. Some of the pictures are of the same cases. I have posted pictures, but other's below have posted better pictures of what a burr looks like.  Here is the link to my pics:

https://flickr.com/photos/131354161@N04/sets/72157650839550371

Please let me know if this is normal? Finding all the brass flakes inside of my gun is concerning to me.

Also, my gun jammed up and would not eject a case on the 15th round of FGMM that I fired. This was also only the 15th round that I have ever fired in the gun. At this time I was using a 20 round PMAG bought from Larue. I have contacted Larue. So far they have been very good to talk to. I have been told to clean the chamber and try again. I cleaned the chamber and this time used the Larue mag. The gun did not jam this time, but the cases are still swiped. The swipes this time are mainly leaving sharp edged burrs. The first time I fired these were mostly swiping the brass clean off and leaving flakes inside the gun. I found flakes in the bore, on the bolt face, and in the locking lug area.

I have mentioned the swipes to Larue, but there is no way for them to gauge how bad the swipes are by talking over the phone and not seeing them. That is why I figured I would post these pictures here so I can see what you guys think. Hopefully you can compare it to your gun. The last thing I want is for the gun to jam again...especially when I plan to start hunting with it.

I also found an article about this here:
http://www.shootingillustrated.com/index.php/8720/case-head-swipe/
What I gather from this article it sounds like there may be something wrong with the gun?
Here is a quote from the article:
When I see anything beyond minimal CHS with any of my handloads, I fix the problem by fixing the load. With a stock rifle showing moderate to excessive case-head swipe with factory ammo loaded with common, mid-range bullet weights, send it to the manufacturer and let it correct the issue. For guns you’ve built, you’ll have to sort it out on your own.

I also tried to check the tightness of the barrel, but noticed that Larue had sent me the wrong barrel wrench which is the one for the 5.56. I did check and the barrel was at least hand tight. It was also set to unsuppressed since I'm not using a suppressor.
I was also using an 30 degree offset aimpoint T1 as this is the only optic I have for it at this time. So the gun was slightly rotated when fired (don't know if that would matter?)

Anyways, any help would be appreciated.

I have seen that on the 14.5" PredaTOBR that belongs to my dad.  It happened with 168 grain FGMM, 175grain FGMM and every handload I have tried with Varget and H4895.  It does not seem to be related to the charge weight of the propellant that I can see.  Like yours, there is usually small flecks of brass that can be seen during cleaning from time to time.   It does not affect every piece of brass, but the majority of them are affected.



I think what you are likely seeing is a timing issue.  Lots of folks will try to adjust their gas block, alter the buffer or buffer spring.  Unfortunately you can't adjust the gas block on your rifle.  This would be the easiest fix.  You may choose to mess around with buffers and/or springs.  This can be frustrating in large frame AR's, as things you would expect to work better sometimes DON'T.  



Whatever the cause, it does not seem to affect the function or accuracy of the rifle.  For us, it has become a non-issue.  





Hopefully since you have posted some very nice pics someone at Larue can give an official word on the matter.





j

 

I too have seen the swipe marks, but no burrs or brass in the rifle.

I have the lightest of swipe marks from my 14.5, I actually had to pivot my case heads in the light to see the swipe.

I get them on all of my 762s, has not caused any issues I can see.

Are you able to tell from the pictures if the swipes you are getting are as bad as the swipes I'm getting? Is yours leaving brass in the gun? Is it leaving burrs on the cases?
Thanks

i get these same markings as well, never had any failure to feeds or any other issue. have about 150 rds through it now, 16 inch preditAR 7.62. They are leaving a small burr but no shavings, I clean the gun every time out and use machine gunners lube for lubrication. I was not to worried but am interested to know. For reference I did build a mega matten 7.62 that does not do this (has jp lo mass bolt and buffer system with adjustable gas block) However the gas is adjusted pretty light on the gun so It is probably not a good comparison. (also since the larue showed up I have not been able to make myself shoot the matten)

Oh forgot  the ammo,, 168 grain hornady supermatch or 168 grain hornady match, I do have not paid attention to see if the superperformance  ammo has more or less of the mark

Had a pretty solid day at the range yesterday.  First time out with the 7.62 MG tOBR return.  Loved it and even just on a day spent sighting in the new winter haul, it's within range of the shootist (next time out) ...

I did find that many of my cases were "swipe'd" as OP has described ... This was consistent with my FG on same rifle ... All rounds are 168gr FGMM and these are just a selection from the bunch ... Roughly 50%'ish were similarly cut.

ETA ... All shots were fired while suppressed (SF SOCOM 762RC) in suppressed gas block configuration ...

100% of the rounds from my OBR 7.62 have looked like the above pics from day one. Mostly shoot 175 FGMM or 168 sometimes, but they all look that way. The brass is pushed up so far it wont fit in a shellholder to deprime unless its turned just right.
Not that I reload for this gun, I just deprime a bunch of brass every so often and store it.
I have around 1000 rds so far.

The brass shavings have never caused a function problem, but I find this level of case head swipe to be quite odd. everyone that has seen what it does to brass says its overgassed, but it works fine. The only malfunction I ever had was when I had left it in Suppressed mode without a suppressor. It would fail to feed on the last 2 rounds of a mag. I took that lesson to mean that much less gas would not be a good idea either so I figured it needed all the gas it was getting when in Unsuppressed mode.

I'm really no help here. I'm just adding that it is common, but no one knows if it means anything bad.

My OBR does this as well.  The only rounds that don't do it are some of my dialed down reloads.

Jerry, hearing from you and everyone else is helpful. Thanks

Mark, is this the thread you were talking about with the choking 308? Just wondering if you were talking about this since my thread is the only one I know about with a problem to extract recently.
I think I may have received the correct barrel wrench today. When I get home I will have to check.

No swipes here... but most of my brass is still piled up on the shooting table. From the ones here with me though there is little to no ejector footprint much less a swipe. They are cases from 168FGMM and 180WinBallisticSilvertip.

I will check my 175FGMM cases tomorrow if I remember.

Nope, this ain't it ...

I missed this thread but will read up.  

Checked my brass. It does not show anything like this. 168gr FGMM, M80 ball, 175gr SSA match, all clean.

if you look at the primers, they aren't showing any signs of flattening, cratering, flow, or any other signs of having over-pressured cases.

I believe the swipe is from the gun starting the unlocking process before the pressures in the chamber have fully subsided. This is why you'll see this swipe be very pronounced on a suppressed gun, ESPECIALLY if you don't have an adjustable gas block.**

How's the accuracy of these 'swiped' rounds?  If there's no overpressure signs (none of the pictures show any) and the guns are accurate (user ability may vary) and the little brass parts aren't causing any function issues, then I'd say keep the chamber clean, lube the gun up, lock and load!

Again, slightly overgassed means reliable functioning, whether it's using TULAmmo or FGMM.




**My two cents about the PST blocks: adjustable gas blocks are different than a selectable gas block. The PST Blocks are selectable, not adjustable. They are very good at what they are meant for: flip the switch, throw the can on there, GO!  They are adjusted to a good setting that will work great for about 99% of the suppressor setups. If an end user comes out with a crazy home built can and the PST doesn't work well with it, well, then that guy just rolled the dice on himself. THe fully adjustable gas blocks are specifically meant to tune the whole thing down to where there isn't an overgassing issue with the gun. There's a fine line between overgassing, and undergassing an AR. For one of my large frame ARs, the difference is one click on the block. I choose slightly overgassed for the reliability.  Also, FWIW, using my adjustable gas block, I still got ejector swipes on my suppressed large frame AR.

Disclaimer:  I have not shot my reloads in my new tOBR (762) yet.

But, ejector swipes like this are a PITA for reloaders.  My SR-25 only did this during load work-up and was a very noticeable clue about pressures (anything above 2650fps produced them).

While I get the "I only shoot factory ammo" statement, reloading is a fact of life for many of us and anything that complicates the exercise (like case damage) is to be avoided.

I am hoping my tOBR does not exhibit this behavior.  I have 12K 180gr SMKs and 6K of brass that will allow me to shoot until I expire.

YMMV,

Mike

I have some of that same marking on my brass 762 14.5

Mike, I have been using stainless steel media to clean brass and find that any swipes made by a 18" or 14.5" 762 tobr come out during a 2hr cleaning.

 

My 16"/7.62 TOBR has had none of these marks. I have about 400 rounds through it thus far with the FG barrel. M80, AE (Federal) 168gr M-1A ammo. I am hoping to take it out and sight in the MG barrel in about a week. Hope it all works out guys....

For those with lots of extra AR parts, try a heavier buffer or a heavier spring..... Please post your results.....

I have never had a problem with reloading brass that has ejector swipes.  If there's a little bur, I just file the bur off.

In a semi-auto gun, I believe more can be told about overpressure by looking at the primers.

Again, with no other overpressure indications, just reload and go.

***ETA I suppose if you're trying to get the absolute best bench-rest accuracy out of your reloads, then I wouldn't use these cases for that. The bur (and the 'crater' left when the bur is removed) can cause a case to sit at a 'slightly' different angle when going through the case prep and even when it's sitting in the chamber it can be off a tiny bit I suppose.... That can lead to inconsistencies.  

If you're to the point that that level of detail matters, then maybe having an Optimized BATTLE Rifle might be not enough gun.. maybe LoL

Stainless steel media ... walnut hulls are last century ?

I went out to the WormHle to look at the cases ...

I've seen this before, but they've been related to overpressure and/or timing

Mark haz a camera in his brain!


Or somebody else took teh pitcher.

Oh look... some ejector swipes from the factory...


Hey Mark.. who's taking the picture if you've got two hands full of brass?

The right hand is the shooter, left is mine.  Camera is in my right hand.  

Well your pic ought to ease some comfort for the OP.

ouborat7,

Never mind your brass issue, bugs me you got the wrong wrench.

Copy and email me your post - mark (at) larue (dot) com

after it gets tightened down correctly, try shooting one round at a time on the suppressed setting. The bolt probably won't lock back, which tells you that the PST is doing its job.  See if that brass has the ejector swipe on it.

only load one round at a time for this.

The FGMM brass always seems exceptionally soft.  I need to look at some of my non-Federal ammo also.  I don't know if this has any bearing at all, but it's certainly the softest I deal with while reloading.

Mark, I sent the email you requested. Thanks to everyone who has posted. I have sort of fallen off the map lately. I will probably be looking over this in more detail in the next week.
Also, I have received the correct 7.62 wrench from Laure, and will be sending back the 5.56 soon.

For the record ... All "swipes" with my tOBRs (unsuppressed, suppressed, gas block on/off, FG, MG, 18, 16, 14.5, etc) have these with FGMM 168 or 175gr.  No pressure signs to speak of ... All clean as a whistle and well lubed. ... Not unhappy with the rifles, just the "New York" times facts for the thread.

I also use stainless media for cleaning cases that I reload and use in other guns ... It does get most of the burs but not all ... It really is a pain since I usually only shoot the new stuff (that drives the rest) with the LTs. Would like to figure it out someday but it's not a priority for me at the moment.

CP.

Thanks for the info. Can't speak on accuracy yet, as I have only messed around with a red dot.
Can you explain why overgassed means reliable functioning? Do you have any links that show what overpressure pictures look like?
Thanks

Best I can tell from those pics, this looks like the very light swipe I was getting when shooting 150gr. The 168 FGMM appear more like the picture with the burr.

I got the 7.62 wrench. The barrel seemed to be tightened correctly, best I could tell.  There has been too much snow and rain here for me to get out and shoot.
I will try this when I get the chance.
So the idea is by putting it on suppressed that it will not allow as much gas to go back? so this might keep the bolt from going back because there won't be enough gas? Are you thinking this won't swipe because it will slow down the timing of when it tries to pull back the case?
Just trying to fully understand the idea.
Thanks

Thanks, let me know what you find out. From the article I posted:  Keep in mind, softer brass used by some manufacturers can exaggerate CHS

Thanks for the info. I was kind of curious if it was different for the different barrel lengths, but this clears that up. What would I be looking for in pressure signs?
Thanks

Looking this thread over, it seems that about 50% have swipes and 50% don't.
It doesn't seem like anyone else has had any issues with the swipes causing problems other than reloading being harder. Basically no one is reporting that it is causing any malfunctions or problems.
Thanks for all the post so far. It does ease my mind that nobody else is having problems with it.

IMHO. Malfunctions aside it would be an issue with me. It should not be damaging the brass unless something isn't right. Once again it just my opinion.

 Sorry , mine are ALL okay .  These are a couple I just happened to have at hand.

Copy and paste this post and shoot me an email with an address.

Mark (at) LaRue (dot) com

I have been watching this thread a while since posting early on.  Having multiple OBR, tOBR rifles in 7.62 from 18" to 14.5" I can say all of the rifles cause swipes with FGMM. Some worse than others. The 14.5 is the worst.  That said it has never caused any issues.  My goal when reloading is the best accuracy possible.  The swipes have not been a detriment to accuracy in my experience.  If the swipes interfere with the priming tool or press shell holder, and this does occasionally happen, I hit it once with a file stroke and issue is solved.  IMO it is normal and acceptable.  The statement you made about flipping the PST to suppressed will just cause unreliable function of your rifle worst case FTF/FTE. But it won't hurt if you want to experiment.



If you are reloading, as you stated above, certain powders will cause swipes worse than others based on port pressure and burn rate.  Did you say you were using red dot.  When you are loading for the 7.62 start low and understand what is listed as max in reloading manuals is typically for a bolt gun.  Some powders you will not safely reach max listed loads in your autoloader.  For instance most manuals list 44-45 of Varget as max with 175 bullets this is not a load for your Larue  or any other autoloader.  I find  one and a half to two  grains is a fairly standard safe reduction off many listed loads in the .308. The higher weight loads may be safe from a case rupture standpoint but you will beat your rifle to death, cause malfunctions and destroy your brass.  This may be part of what you are experiencing now if Red Dot is indeed your powder.  What you are experiencing IMO is not an issue it is just what it is.  I would continue on and enjoy your piece of rifle making excellence.  I hope this gives you some useful information.

 

I get some pretty decent swipes on my 16" obr with factory and reloads ammo
Never affected accuracy.  Initially I was concerned but I did find some older threads regarding it.

Also when I picked up some other dudes brass at the range, it was some factory pmc he fired thru a bolt action rifle. It was f'd up. mega swipes and bulging primers. I didnt feel worried anymore.

I can take some pics tonight. I have a good amount I havent tumbled yet. And I got the scary pmc I think in a trash box

Email sent.

Thanks for the information!
I'm not reloading. Would like to eventually learn how, but haven't started yet, but I am saving the brass. As far as red dot goes, what I was saying is that I'm using a red dot aimpoint T1 sight that is offset. The point I was making was that the gun was not in its normal orientation, but was rotated counter clockwise about 45 degrees. I just didn't know if this affects the guns extraction abilities so I mentioned it.

What did the older threads say?

omd-what barrel length and model?

16" 7.62 obr, non suppressed. 4k serial number.


Iirc, the older threads were similar to what most guys say here. The near max powder#s, the more brass looking beat up. Lower the charge, saw less swipes

My above photo is bh 168 match and hornady 168 match. Most were ok, but he front row had the deepest swipes. The others were much less.

My reloads with Winchester brass was pretty minimal, the lapua brass was also minimal. Maybe quality of brass plays a role in it?
I don't recall if I have any lake city brass, ill have to check later.

I might have tike to jump on the desktop computer tomorrow,I may have some old threads saved. I just googled it all. Same for reloading info.

I fiannally got around to looking at some of my brass... all normal... Federal XM80 and FGMM 175's...

Looked at all the brass shot through my 14.5 tOBR and no signs on any of the brass.