Odd markings on casings after firing

[ahb81]

I took my new RRA LAR-8 out for the first time today and noticed that it was smashing the backside of the casing. It has been many years since I fired a simi-auto, but I never remember the casings ever looking like this. Is this normal, or whats causing it?
Thanks,
Allen

 

[rrflyer]

Re: Odd markings on casings after firing

Are these reloads?

 

[ahb81]

Re: Odd markings on casings after firing

no they are not, just some winchester cxp2's, it maked everyone that I fired today (40) with the same makings.

 

[BCP]

Re: Odd markings on casings after firing

No that's not normal there should be a light half-circle imprint nothing more. You need to call RRA.

 

[Tactical22]

Re: Odd markings on casings after firing

Looks like signs of high pressure to me, especially with what looks like a flattened primer.
Had similar symptoms with my .308 AR Fultonstein I built recently. Had the headspace/chamber/leade/throat area checked, and they were good. It came down to a gas adjustment issue, which made me very glad that I used an adj. gas block. After adjusting it for my loads, the gun runs flawlessly.
I would recommend a similar approach.

 

[aquinas]

Re: Odd markings on casings after firing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body">No that's not normal there should be a light half-circle imprint nothing more. You need to call RRA. </div></div>

Do you mean an ejector mark? If so, those are normal?

OP: consider a Carrier Weight System from Tubb. Solved my problems in an AR-10.

 

[bohem]

Re: Odd markings on casings after firing

Looks like the system is over-gassed a little bit with this ammo.

Some marks on case heads are normal in the bigger semi-auto platforms, however that is somewhat excessive.

 

[litotes15]

Re: Odd markings on casings after firing

I am getting some similar markings from my new pof 308 using federal xm 7.62x51, Winchester 7.62x51 150fmj, and American eagle 308 fmj, but my markings are two dimples on the case neck as well as extractor. I also have a he'll of a time getting the spent shell case out of the chamber after some are fired. I have to push a cleaning rod down the barrel and two hand pull my ass off on the T handle. Anyone have a solution or is it because it is new and tight?

 

[ahb81]

Re: Odd markings on casings after firing

Emailed RRA late last night, and received a phone call first thing this morning. A + on customer service. UPS will be by tomorrow to send it back for an inspection. Thanks for all the inputs

 

[aquinas]

Re: Odd markings on casings after firing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: litotes15</div><div class="ubbcode-body">I am getting some similar markings from my new pof 308 using federal xm 7.62x51, Winchester 7.62x51 150fmj, and American eagle 308 fmj, but my markings are two dimples on the case neck as well as extractor. I also have a he'll of a time getting the spent shell case out of the chamber after some are fired. I have to push a cleaning rod down the barrel and two hand pull my ass off on the T handle. Anyone have a solution or is it because it is new and tight? </div></div>

I get dimples on my necks with my LR-308.

I know this: it has a very tight chamber...just a hair under 1.630. It feeds factory ammo just fine and I cautiously keep an eye on brass to make sure the shoulders get hit enough when I size...about .003 setback.

But the dimples are confusing me.

Here's a clue: i get almost zero case growth from that gun...especially after I installed the CWS from Tubb.

Sure would like to know where those dimples come from.

 

[BCP]

Re: Odd markings on casings after firing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: litotes15</div><div class="ubbcode-body">I am getting some similar markings from my new pof 308 using federal xm 7.62x51, Winchester 7.62x51 150fmj, and American eagle 308 fmj, but my markings are two dimples on the case neck as well as extractor. I also have a he'll of a time getting the spent shell case out of the chamber after some are fired. I have to push a cleaning rod down the barrel and two hand pull my ass off on the T handle. Anyone have a solution or is it because it is new and tight? </div></div>

Tight chamber? Measuring your fired brass will give you an idea about what's going on.

 

[litotes15]

Re: Odd markings on casings after firing

thank you guys for the info. i have not started to reload yet but will start soon anyway; so a set of calipers will be the first purchase i guess. I will grab a pair from midway and let you know my findings on case length. I also tried to email and call POF about the issue asking for help or suggestions, but I may as well be talking to a goldfish. POF customer service sucks bad!!!

 

[Kyshooter]

Re: Odd markings on casings after firing

The dimples on the necks a likely from hitting the ejection port at some point in the ejection cycle, look around just inside of your ejection port for brass marks. Mine does it to every case in as close to exactly the same spot as can be called such.

 

[aquinas]

Re: Odd markings on casings after firing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kyshooter</div><div class="ubbcode-body">The dimples on the necks a likely from hitting the ejection port at some point in the ejection cycle, look around just inside of your ejection port for brass marks. Mine does it to every case in as close to exactly the same spot as can be called such. </div></div>

Dunno. They don't look like they are produced by the ejection port. I know they beat up the forward assist boss pretty good on the way out.

The mark looks like it could be produced by the lugs. It looks like the imprint of the corner of a lug.

That said...I've heard nipping a few coils off the ejector springs can cure this problem. I might give that a try.

 

[USW.260]

Re: Odd markings on casings after firing

Its called Case Head Swipe...and everyone one is right but just in a bunch of replies. Over gased a little, marks on neck are from lugs, buy a Tubb CWS before you cut springs. I say its all about the pressure curve. When I Reload for an Atuo and have any CHS "Case Head Swipe" I before anything else choose another powder. And Most importantly run your Dies to the shell holder and then in 1/16th or 1/8th and you will be fine on all your resizes after that. Now don't worry about what people say about sizing, run to the shell holder on a normal set of dies "not small based" and in a little if you want. Its an Auto- You've gotta Feed the Machine! But remember new brass will shoot a little different, don't go thinking somethings wrong. Also if you were shooting Winchester ammo, your barrel and gas system might not like there powder which I believe is W748. Find a medium burn rate powder "Varget,IMR4064,IMR4320,RL15" and start low and then work up. I have found out that most of the time my best loads are made of low to mid charges of whats in the books Max. Also If you were to say buy a Hornady Reloading book and then get a Hodgen Manual "magazine" the lows and highs are sometimes off a grain or two. IF I were to make a load right now for a new AR10 and I needed that load to shoot really good to see how accurate a rifle was it would be ...Win brass, CCIbr2 primers, 42.0gr of Varget, and a 175gr SMKs seated to 2.800 from case head to bullet tip. And I have found out that throwing charges from a good powder measure "RCBS w/micro meter" will be as accurate and if not more than weighing every charge. Good Luck.

 

[Sulenski]

Re: Odd markings on casings after firing

Another thing to consider is checking the gas block to see if its in the N position or the S position.

I did ask someone about the case head swipe and I was told it was safe to reload. I have a couple hundred of these cases that I have picked up from range clean ups and havent got around to messing with them.

 

[msalm]

Re: Odd markings on casings after firing

Remove your ejector and round the edges and polish it smooth. Looks like it's just the ejector scraping up the backside of the case.

 

[WRM]

Re: Odd markings on casings after firing

OP's picture looks like over pressure to me - Brass is flowing into the ejector hole, and brass flow is not good.

Dimples on the neck may be caused by the lugs on the barrel extension during feeding.

Just possible explanations, and there certainly may be others....

Cheers,

Bill

 

[aquinas]

Re: Odd markings on casings after firing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: USW.260</div><div class="ubbcode-body">Its called Case Head Swipe...and everyone one is right but just in a bunch of replies. Over gased a little, marks on neck are from lugs, buy a Tubb CWS before you cut springs. </div></div>

Currently running a CWS with heaviest weight in it and getting neck dings.

Are you saying case neck dings from the lugs are a sign of over-gassed, or was that in reference to the CHS?

was seeing much more pressure signs with H4895. Switch to RL-15 has lessened pressure signs...except of course the neck dings.

 

[USW.260]

Re: Odd markings on casings after firing

Neck dings.... I mean what else inside your upper can make two dings like that other than the lugs... I also beleive it happens on the way out not in. Gotta Remeber the case is slightly larger onces its fired. Now when I have ran a round into an upper and then had to run the bolt back to extract round for what ever reason the bullet itself has the same marks....from the lugs...and the brass didn't but once fired the marks are on the neck. Oh well just keep buy winchester brass, its good stuff and not that expensive. If you mess a bunch up then thats fine do your best to fix it or forget it and buy some more.

 

[litotes15]

Re: Odd markings on casings after firing

Well guys this is odd but for some reason or the other, the banged-up brass issue has stopped all together....odd, nothing done different but a cleaning... Also, just got rid of the eotech and moved up to leupold and doing some shooting and was puzzled. 3 shot group of plain old American eagle 150 fmj I was using could cover a dime at 100 meters. My federal gmm 168 and 175 bthp where 1.5!!!!! I was furious!!!! Ranged 200 meters and shot .5" groups with the gold medal match 168 and 175's. How can this be????? Went through about 20 rounds each brand and got same results; all from POF 308. Any ideas

 

[USW.260]

Re: Odd markings on casings after firing

HIMaster.... In refrence to CHS.... Its more like the bolt running back and rotating at the same time..as it was made to do... before the brass has a chance to come back to size after being fired. The brass is still swelled up and the bolt is starting to backout and rotate before it needs to....in this case its because of the pressure curve of the powder that is being used. Alot of times factory ammo may or may not have this problem. It just depends on there load and what powder they are using and what the gas system of that perticular rifle needs or likes. Factory ammo is made to run in Any Gun-Ever Time. Reloaders run into this pressure problem right off the bat and think OMG somethings wrong with the gun when there isn't. With a Bolt Action rifle powder and pressure are not that big a deal untill you get around the Max charge and start seing flattened primers and such. Bolt guys almost only worry about Velocity. Auto guys need to worry about the Pressure Curve, Burn Rates, PSI and CUP, Seating depth, Brass quality and thinkness, Primer pockets "how loose they are after 2 reloads", and then Velocity. Mostly I worry about Velocity very last in an auto b/c I already know its going to be lower than a bolt gun. And its when auto guys start chasing after that higher velocity they or there friend has in a bolt gun that they run into trouble. And One more thing I always try to remember is that all the components that make up an AR10,15 are made to run..like a Machine, they are enginered around Factory Made Ammo and those kind of Pressures from the beginning with the Battle Field Reliability in mind. So yeah you will have some weird things happen to your brass...just look at it and listen to what its telling you.

 

[USW.260]

Re: Odd markings on casings after firing

Litotes15....Gas Pistons man. Almost a different kinda animal. I tell you what though I had some of the 168gr American Eagle MIA ammo that I tried out of my Armalite/Eagle AR-10 and that shit would clover leaf at 200, same as my 175smk load I suggested earlier. If I had any Idea it would be to slow down...really pay attention to your shooting Form. What did the 150s do at 200? Your system might just like the 150-155gr range of bullets and what drives them, who knows. Take a note pad, right down all the veirables that you can think of and then mark them out one by one when you know they are mastered. An Auto has so many things going on. Remember the 3 Recoils, trigger reset, grip/hand placement. With groups that nice out of both loads you have to remember to include the Indian not just the bow and arrows in the whats wrong game, but to me it sounds like you can shoot. Also see how they do at 300 and 400...farther if you can. With an direct gas inpengment system you have the barrel, gas tube, and bolt....gas goes from barrel to bolt nothing inbetween to "get in the way of things". With your piston setup well could be a few things that I don't even know of. And I am for sure not a know it all...I just have some usefull information. Maybe someone with a POF can chime in. This is a good thread.

 

[litotes15]

Re: Odd markings on casings after firing

usw260- thank you for your help man really appreciate it. I am no veteran shooter thats for sure but I try like hell. the american eagle 150gr's @ 200 meters shot just about the same .5"-.75" mark. Again I am not sniper like some of the others here. Also a little confused about the 168-175gr GMM. Every post I look at states like gospel that 1:10 twist must shoot 168 or higher and thats that... 300 meters will be coming up later this week and will post any significant findings as well as the pof's ability to turn off the gas system to operate same as bolt gun. we shall see how that works for the accuracy.