Ar 15 new Buffer and spring = Damaged brass?

[Keele]

I have PWA 5.56 that I converted to a collapsible stock, I noticed right away that it a bit harder to pull back the charging handle. Thought it was just my old buffer spring was getting weak compared to the new one. Went to the range, cycling fine, bit more crisp for sure. I fire a few more times and i started to notice small scratches on the rear of the brass just above and below the primer when they were ejected. The brass is getting shaved a little bit and leaving small ridges that you can feel with your finger nail. Like the round is getting chambered and turning 1/16" or a bit less.
Anyone had a problem with the bolt cycling to hard. Is there an easy way measure this and then trim spring to adjust it to a standard tension? Or do you think i have another issue i haven't thought of yet

 

[GLShooter]

Re: Ar 15 new Buffer and spring = Damaged brass?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Keele</div><div class="ubbcode-body">
I have PWA 5.56 that I converted to a collapsible stock, I noticed right away that it a bit harder to pull back the charging handle. <span style="font-weight: bold">Thought it was just my old buffer spring was getting weak compared to the new one</span>. Went to the range, cycling fine, bit more crisp for sure. I fire a few more times and i started to notice small scratches on the rear of the brass just above and below the primer when they were ejected. The brass is getting shaved a little bit and leaving small ridges that you can feel with your finger nail. Like the round is getting chambered and turning 1/16" or a bit less.
Anyone had a problem with the bolt cycling to hard. Is there an easy way measure this and then trim spring to adjust it to a standard tension? Or do you think i have another issue i haven't thought of yet
</div></div>

Did you leave the rifle length buffer spring in the collapsible stock tube? They are different as are the buffers. That may be part of the issue. If the stock is all you changed I do believe the spring is the culprit.

Greg

 

[Keele]

Re: Ar 15 new Buffer and spring = Damaged brass?

Sorry about that, The tube,spring and buffer were a set.

 

[citation04]

Re: Ar 15 new Buffer and spring = Damaged brass?

sounds like a piece of cake. First of all where is the weapon currenlty ejecting spent brass? 5o'clock, 3 o'clock 1 etc. and how far is it being ejected, I don't really care about the distance but more about what is different as far as direction and power its being ejected at compared to before.
Thats just a minjor clue though, most importantly are you aware of what weight buffer you were running previously, and what weight buffer you are using now. Im not sure I follow you when you say that the brass is being damaged while being chambered, its just being stripped and chambered, what is happening I believe and what is usually the case is that the balance has shifted between your spring and buffer which is now allowing the BCG to cycle to fast and hard hence causing ejection that is dmanaging the brass on the wayout.

Buffers come in 3 main weights (sometimes four) if it is a heavy buffer it will have a n H stamped on the face. let me know and well take it from there

 

[Keele]

Re: Ar 15 new Buffer and spring = Damaged brass?

If you are still around, Work had me out of town for a bit. I looked at the buffers and i am unable to find any markings on them to indicate what weight they are. I got to get out to the range and fire some rounds off, I was prone when i fired and the brass was ejected at a distance of approx 4 feet away at an angle 45 deg. (or 2 O' Clock) same thing, damaged brass. What i am thinking is the brass is getting damaged when the bolt chambers the round in the breech and the bolt turns to lock in.
When i watched the action of the bolt compared to the damage on the rear of the brass it has to be what the problem is.
Is there a way i can figure out what weight buffer i should get with no markings to go by?

 

[mtrmn]

Re: Ar 15 new Buffer and spring = Damaged brass?

I don't want to hijack this thread, but I felt I needed to throw my $.02 in.

Normally unmarked buffers are the standard weight. Heavy buffers will normally be marked H, H2, H3.

Look around on the site below and you should find a chart showing the weights of the different buffers. This guy has researched buffer weights for quite a while and is very helpful if the buffer is indeed your problem.

http://www.heavybuffers.com/

I bought an H3 buffer (with 3 tungsten weights) and took it apart along with my std buffer with 3 steel weights. You can mix/match weights from both and make any of the 4 different weight buffers with this combination. If you have a buffer with 1 tungsten weight and the other 2 are steel, you have an H buffer. If you put 2 tungsten weights, it becomes an H2 buffer. etc etc

In this way you only have to buy one heavy buffer (instead of 3) and then you can determine the heaviest buffer you can run and the gun still locks back on an empty mag. This needs to be tested with the WEAKEST ammo you intend to use.

 

[Keele]

Re: Ar 15 new Buffer and spring = Damaged brass?

I will take your $ .02 gladly. Thank you i will check that out. it sounds like just the thing i need to look at.

 

[BDHershey]

Re: Ar 15 new Buffer and spring = Damaged brass?

What upper (brand, barrel length, gas system length, etc) are you running? I'm not following where on the casing the marks are. Could you post a picture of the chewed up brass? You may be over gassed and under sprung/buffered. You may need to move up to an H or H2 buffer or try a different recoil spring. Don't trim the recoil spring.

 

[mtrmn]

Re: Ar 15 new Buffer and spring = Damaged brass?

I will add that all my 16" carbines were over-gassed and I installed Wolff extra-power springs and wound up with H2 or H3 buffers in all of them. But each gun is different and needs to be tested for reliability. I got the springs from Brownells and buffers wherever I found them as I went from 1 gun to the next.

All mine have semi-auto bolt carriers which are lighter than full auto carriers. The carrier type you have is something to consider as well.

All this assumes your trouble is with the reciprocating weight/overgassing. If your chamber is not a TRUE 5.56 that could cause you pressure problems as well. I own several ARs that were marked 5.56, but when a true 5.56 reamer was run through them there was a lot of metal removed from the throat. The throat is where most, if not all, the difference is between 5.56 and .223. The 5.56 has a much longer throat for the higher pressures.

 

[problemchild]

Re: Ar 15 new Buffer and spring = Damaged brass?

The marks, if I am reading you right, are called ejector smear. They come from over-gassing. The 2:00 also tells you that you are over-gassed. I would NOT run a heavier buffer. I would buy an adjustable gas block like JP and tune your gas down so its not kicking as hard.

I just went through this myself.