Gunsmithing Question about POF 308 marking up brass

[SmokeRolls]

Bought a POF complete upper with a mike rock 20" barrel and a low round count and it seams to be shooting nice but it's leaving two groves/gouges in the brass on the neck (I think it's hitting the locking lugs as it's being pulled out and ejected)and sometimes leaving a dent on the below the bottom edge of the shoulder.
Is this a timing issue?, Or?
I built the lower using a full length tube and bought a buffer which I was told it was a 308 buffer but later I found out it was a AR-15 full length buffer. I didn't have another buffer and I was told by an AR armorer that I could cut the buffer down and move the pin and shorten the buffer and it would work. I also had to trim some length off of an aluminum spacer that was inside of the dampner so it would have enough free space to move and dampen. When you shake it back and forth, it sounds and feals like a dampner should. The total length on the dampner is 5.225 (If my memory is correct). I also bought a dampner spring from the same guy that I bought the buffer and it's a heavy duty spring and it appears to be a long one as well. I will say it's a lot harder to pull back the bolt and chamber a round than my buddys stock AR-10T.
It chambers and ejects just fine, it just gouges /dents up the brass.
I have ordered a standard Armalite 308 /AR-10 full length buffer and an Armalite 308/AR-10 A-2-full length spring for comparison.
Ideas or insight would be highly appreciated.
I just hate to destroy brass that I could be using in the reloading process.
......SmokeRolls

 

[Insayn]

Re: Question about POF 308 marking up brass

On my .308 gas gun the grooves in the neck are from feeding up the ramps. The dent could be from the case hitting something while being ejected, typically the port or deflector.

 

[lvcatfish]

Re: Question about POF 308 marking up brass

This can often be improved upon with patience and elbow grease. Most .308 size semi's eat brass to some extent. Do you have pictures? Define "destroy brass" are we talking unusable? I don't expect to get the same brass life from a semi that I do from a bolt gun. I often start new brass through the bolt gun for several firings and then retire the brass through the semi. I have had some success with rounding rough edges off and tuning gas pressure. You are somewhat limited in tuning pressure based upon the size and location of the gas port. A piece of rubber glued to the deflector may help some (if the deflector is the culprit). The buffer tube/spring may be impacting bolt cycling (extraction).

 

[SmokeRolls]

Re: Question about POF 308 marking up brass

I'll get some pics up.
The two marks and the dent are all aligned together, or I should say, "The dent is centered between the two marks only it is just below the bottom of the shoulder". I'll look and see if the extractor left any marks to help figure out the location of the conflicting area.
.....SmokeRolls

 

[SmokeRolls]

Re: Question about POF 308 marking up brass

Here they are.
They look a little worse in person, they are deeper than the pics are showing.
Also, all the marks on the neck and the marks below the shoulder line up with the extractor marks.
All the marks are on the same side of the case.
This brass is brand new Federal Gold Metal match factory loads.
.....Smokerolls

 

[nfoley]

Re: Question about POF 308 marking up brass

I have the POF 308 and it does not do that. I did have some timing issues initially which POF fixed. Problem I was having was with the Hornady TAP 168s. They were not feeding reliably and the casings were getting small chunks ripped off the rim of the casings. The extractor was doing its job, but was trying to extract too early in the cycle. I would suggest emailing POF with some pics. My POF is still a little picky about ammo but with my current handloads works flawlessly.

 

[SmokeRolls]

Re: Question about POF 308 marking up brass

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">I have the POF 308 and it does not do that. I did have some timing issues initially which POF fixed. Problem I was having was with the Hornady TAP 168s. They were not feeding reliably and the casings were getting small chunks ripped off the rim of the casings. The extractor was doing its job, but was trying to extract too early in the cycle. I would suggest emailing POF with some pics. My POF is still a little picky about ammo but with my current handloads works flawlessly.</div></div>
What are the specs of your handloads?
I may use yours as a comparison.
....SmokeRolls

 

[lvcatfish]

Re: Question about POF 308 marking up brass

Good advice above and I will try to provide a more detailed answer when I have more time later today. I gave up on FGMM brass in my DPMS LR308. The brass is soft and did seem to get chewed up worse than other brass I tried (PMC, LC, Win, R-P). I was only getting 1 semi auto reload out of FGMM brass that was once fired through a bolt gun (loose primer pockets, ejector marks etc). The load was not hot and the problem went away when I switched brass. Those marks are not likely to disappear completely if you change brass. You need a tune up.

 

[Edgewater]

Re: Question about POF 308 marking up brass

My P308 leaves the exact same gouges and dents in my brass. I have to say that the gouges are not quite as deep as the were when the rifle was new but still leaves them nonetheless. I thought that it might be due to the feed ramps being too sharp and over time would wear down. I have not worried too much about it as I am still able to reload the brass. I'm interested to hear others feedback on this issue.

 

[AlterEgo]

Re: Question about POF 308 marking up brass

It's 100% the scrapey-scrape on the locking lug at extraction. If you polish the edges/corners of the locking lugs that will lessen greatly. That's what I did at least. Advise removing barrel ass'y from receiver if possible...

 

[nfoley]

Re: Question about POF 308 marking up brass

My favorite loads are winchester brass and WLR primers with 44 grains of varget and 168 Amax or SMK. Either bullet shoots well. I consistenly get around 1 1/4- 1 1/2" groups at 200yds with this load. The ejector marks are slight, and I have a batch of winchester brass I have loaded 5 times so far and they still look good. I seat the bullets to 2.805". Will be trying some 175 SMK just because a friend had some that he did not like and gave them to me to try. Will let you know how they do when I get around to shooting them. My POF has the 14.5" barrel and I get around 2450fps with the above mentioned 168s. I will say again this particular rifle is a little picky and for some reason have had trouble with factory 150g winchester and federal rounds that don't feed very well through it (and get 2-3" groups at 100yds when they do feed). For factory loads it likes the FGMM 168, TAP 155 and TAP 168 rounds for accuracy and reliability. Good luck!

 

[SmokeRolls]

Re: Question about POF 308 marking up brass

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">My favorite loads are winchester brass and WLR primers with 44 grains of varget and 168 Amax or SMK. Either bullet shoots well. I consistenly get around 1 1/4- 1 1/2" groups at 200yds with this load. The ejector marks are slight, and I have a batch of winchester brass I have loaded 5 times so far and they still look good. I seat the bullets to 2.805". Will be trying some 175 SMK just because a friend had some that he did not like and gave them to me to try. Will let you know how they do when I get around to shooting them. My POF has the 14.5" barrel and I get around 2450fps with the above mentioned 168s. I will say again this particular rifle is a little picky and for some reason have had trouble with factory 150g winchester and federal rounds that don't feed very well through it (and get 2-3" groups at 100yds when they do feed). For factory loads it likes the FGMM 168, TAP 155 and TAP 168 rounds for accuracy and reliability. Good luck!</div></div>
You must be using metal mags with the seating depth at 2.805".
I'm using magpuls and I had to go to 2.793" for the 168 smk's to have enough play to move around in the mag.
I just made up some handloads with Federal brass and 43.5 grains of Varget and BR-2 primers. Have yet to try them. I'm kinda waiting until the stock Armalite Buffer and spring arrive in the mail.
......SmokeRolls

 

[Insayn]

Re: Question about POF 308 marking up brass

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Insayn</div><div class="ubbcode-body">On my .308 gas gun the grooves in the neck are from feeding up the ramps. The dent could be from the case hitting something while being ejected, typically the port or deflector. </div></div>

After re-examining some nickel casings shot though mine I can see where the ejector leaves a mark on base and lining that up with the marks on the neck and shoulder I would say it is from extraction and scraping on the lugs on the way back. I never really payed attention to them since I don't reload these. The marks aren't as bad now as there were when I had less rounds through the rifle, but noticeable.

 

[Edgewater]

Re: Question about POF 308 marking up brass

Seems to be quite common since I have seen other posting (on some AR site) that show the same. Seems to be from sharp locking lugs. As stated above, mine have since gotten better with more rounds fired. Thanks for the confirmation.

 

[SmokeRolls]

Re: Question about POF 308 marking up brass

Thanks. I appreciate the imput and observations.
I guess a couple sharp edges on the locking lugs need to be slightly smoothed (And I mean very slightly) or I may just shoot it for a while and the sharp edges might just wear down over time. I just hate to have damaged brass if there is a way to avoid it. Brass is not as common as it once was.
....SmokeRolls

 

[nfoley]

Re: Question about POF 308 marking up brass

TheSmokeRolls,
I use metal mags but I also have a magpul magazine and the rounds function in the magpul as well. Factory Federal 168 SMKs are 2.80" and they should work fine in your magpul. Not sure why your magpul only allows 2.793?

 

[lvcatfish]

Re: Question about POF 308 marking up brass

A little light polishing should help this. New ejector springs are strong and these types of marks will tend to lessen with time as the springs (and other bolt parts) wear in. Like others have suggested the purpose is not to remove metal but rather to round off the rough edges. It may be helpful to place an index mark on a loaded round with a sharpie and then hand load the round noting the position of the mark. After firing the round check the scrape marks in relation to the index point.
If you do decide to polish remember to thoroughly clean the lug recess area before re-assembly.

 

[SmokeRolls]

Re: Question about POF 308 marking up brass

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">TheSmokeRolls,
I use metal mags but I also have a magpul magazine and the rounds function in the magpul as well. Factory Federal 168 SMKs are 2.80" and they should work fine in your magpul. Not sure why your magpul only allows 2.793?</div></div>
2.80" would work but it looked like it was touching at the tip of the bullet and I felt like giving it a touch more room so I dialed it in a touch. <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lvcatfish</div><div class="ubbcode-body">A little light polishing should help this. New ejector springs are strong and these types of marks will tend to lessen with time as the springs (and other bolt parts) wear in. Like others have suggested the purpose is not to remove metal but rather to round off the rough edges. It may be helpful to place an index mark on a loaded round with a sharpie and then hand load the round noting the position of the mark. After firing the round check the scrape marks in relation to the index point.
If you do decide to polish remember to thoroughly clean the lug recess area before re-assembly.</div></div>
Nice advice, will do that.
New factory Armalite buffer and spring came in the mail today, will also try that to see if this also makes any difference. The buffer spring I had in the rifle was way stiffer and harder to compress than the factory Armalite one I just received in.
Thanks guys
.......SmokeRolls