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Posted: 9/4/2010 11:17:52 AM EDT
Hi I have three AR Variant type builds now, two from 60% lowers and one using a Spikes lower. They all have had approx 750 rounds thru them, all working great except for an occasional mis- load from a magazine not being loaded correctly.....But Over all…..Lots of fun!
After last week’s shooting I gave them all a deep disassembly and cleaning, Amazing how much shit actually gets into the pin/ bolt area!!!! Anyways, while cleaning....I noticed a "hammered" almost regular pattern around the face of all three buffers....from where they strike the pin on the buffer detent. Is this normal?
Am I doing something wrong?
Is this something to be concerned with?
Does it need more grease..or is this a big nuthin’?




And a couple pics of "Numba Three":




Uploaded with ImageShack.us

Any suggestions or help will be appreciated
Link Posted: 9/4/2010 11:50:31 AM EDT
Your close up pictures are really blurry so it's hard to tell for sure (need in focus close ups of the side and face of the buffer) but I have a gun with about 5-600 rounds through it and my buffer doesn't look anything like that ... it almost looks like the buffer is slipping over the detent and then back again while cycling?
Link Posted: 9/4/2010 12:11:47 PM EDT
mine look like that, but they have way more rounds thru them.
I'm not worried about it.

always wanted to cut my own lowers.
Link Posted: 9/4/2010 12:12:02 PM EDT
Yeah...my digi Camers bites!
Wouldn't there be marks on the side of the buffer if it was going past or over the detent?
I'll try another camera

Thanks!
Link Posted: 9/4/2010 12:27:55 PM EDT
Originally Posted By Gryme:
Yeah...my digi Camers bites!
Wouldn't there be marks on the side of the buffer if it was going past or over the detent?
I'll try another camera

Thanks!


Try it on the 'macro' setting. That's the setting with the little picture of a flower on it. It's intended for detailed close-ups.
Link Posted: 9/4/2010 12:28:07 PM EDT
Originally Posted By Gryme:
Yeah...my digi Camers bites!
Wouldn't there be marks on the side of the buffer if it was going past or over the detent?
I'll try another camera

Thanks!


That's why I was asking for a side view to check for that ... I do have one rifle that has maybe 2000-3000 rounds on it ... it has some lite marks but yours looks way worse (or maybe it's the blurry pic combined with my blurry eyes that make it look that way)
Link Posted: 9/4/2010 12:52:47 PM EDT
Tentative opinion pending sharper photos: I would think if the buffer was slamming into the pin hard enough to mark up the buffer like that it would have snapped the top of the pin off by now or at least bent it over pretty severely.
Link Posted: 9/4/2010 12:59:18 PM EDT
Originally Posted By JustKeepSwimming:
Tentative opinion pending sharper photos: I would think if the buffer was slamming into the pin hard enough to mark up the buffer like that it would have snapped the top of the pin off by now or at least bent it over pretty severely.


So what would cause that? All of these AR were built from name brand parts....Aren't the recoil spring and the buffer supposed to be matched?

What else could it be?

Thanks all for the Help!!!

I'm still looking for a better camera.......
Link Posted: 9/4/2010 1:29:14 PM EDT
[Last Edit: 9/4/2010 1:30:15 PM EDT by Gatorhunt]
Originally Posted By Gryme:
Originally Posted By JustKeepSwimming:
Tentative opinion pending sharper photos: I would think if the buffer was slamming into the pin hard enough to mark up the buffer like that it would have snapped the top of the pin off by now or at least bent it over pretty severely.


So what would cause that? All of these AR were built from name brand parts....Aren't the recoil spring and the buffer supposed to be matched?

What else could it be?

Thanks all for the Help!!!

I'm still looking for a better camera.......


It's looks as though the buffer is riding high on the detent .. but again the pictures are to blurry to tell for sure.

ETA or the detent is being held down to low by the tube?

Here's my Colt 6920 .. this is the one that has 5-600 rounds on it for a comparison.



Link Posted: 9/4/2010 1:32:03 PM EDT
[Last Edit: 9/4/2010 1:41:00 PM EDT by RLR350]
To me it looks like the buffer is hitting the pin just enough to cause the damage.

Slowly close your upper with the BCG in onto the lower. Watch the gap between the upper and the lower where the rear of the carrier makes contact with the buffer. Does the carrier push the buffer off the retainer pin? It's supposed to. In other words when closed, the buffer should not be able to touch the pin.

Are you sure it's happening in all three lowers or is it possible it's only happening with one or two of the lowers, but you have inadvertently switched all three buffers into the one or two lowers that could be causing it? My thought is the buffer retaining pin hole on the 60%'s may be slightly too far to the rear not allowing the carrier to push it off the pin. It wouldn't be off much, just enough to let the buffer strike the pin each time the gun cycles, but not enough to cause the pin damage. However, the finish on the culprit pin(s) should show at least some wear.

Of course I'm just guessing here based on the photos.

ETA: Sometime you will see damage to the buffer face from a burr on the back of the carrier. However, this usually produces scratch marks across the face from scraping when opening and closing the buffer along with the circle damage from cycling and rubbing the burr. Also, since you are saying it happens in all three guns, it would mean all three carriers have a burr - or you are switching the buffers. This could be the problem, but not as likely.
Link Posted: 9/5/2010 3:34:57 AM EDT
Is the damage to the buffer all around the outer edges? It looks to me like the buffer is sticking too far out of the lower receiver extension tube. What does the rear of the upper receiver look like?
Link Posted: 9/5/2010 4:39:27 AM EDT
Are you talking about the outer edge of the buffer ?

You say all three are like that.

Is the receiver extension tight , to spec's ?
Link Posted: 9/5/2010 11:24:04 AM EDT
[Last Edit: 9/5/2010 11:25:58 AM EDT by Gryme]
Man....I need a better digital camera....I took more pics...they suck!

Originally Posted By RLR350:
To me it looks like the buffer is hitting the pin just enough to cause the damage.

Slowly close your upper with the BCG in onto the lower. Watch the gap between the upper and the lower where the rear of the carrier makes contact with the buffer. Does the carrier push the buffer off the retainer pin? It's supposed to. In other words when closed, the buffer should not be able to touch the pin.

When I did the above suggestion.....it looks like the BCG is NOT touching the buffer....so when I drilled this hole...maybe it's too far towards the rear.....crap. I read once of a guy on Arf running witout the buffer detent and spring....any down sides to my set up and / or running without the detent and spring (besides the obvious of tearing it down without the buffer and spring taking off!)
Ther are no scratches beyond the rim.....they are more dimples or really small dents on the top edge of the buff.....right where it is hitting the buffer retaining detent.

Thanks!
Link Posted: 9/5/2010 11:57:05 AM EDT
Originally Posted By Gryme:
Man....I need a better digital camera....I took more pics...they suck!

Originally Posted By RLR350:
To me it looks like the buffer is hitting the pin just enough to cause the damage.

Slowly close your upper with the BCG in onto the lower. Watch the gap between the upper and the lower where the rear of the carrier makes contact with the buffer. Does the carrier push the buffer off the retainer pin? It's supposed to. In other words when closed, the buffer should not be able to touch the pin.

When I did the above suggestion.....it looks like the BCG is NOT touching the buffer....so when I drilled this hole...maybe it's too far towards the rear.....crap. I read once of a guy on Arf running witout the buffer detent and spring....any down sides to my set up and / or running without the detent and spring (besides the obvious of tearing it down without the buffer and spring taking off!)
Ther are no scratches beyond the rim.....they are more dimples or really small dents on the top edge of the buff.....right where it is hitting the buffer retaining detent.

Thanks!


I would just remove the detent then ... it's only there to stop the buffer and spring from flying out when you open the rifle up ... just be prepared to stop it with something before the upper is completely pulled off the lower and you should be fine.
Link Posted: 9/5/2010 3:15:06 PM EDT
It's not a big deal. I've never done a 80% or a 60% lower and it looks like you did a good job on it! At least it's a hole that doesn't matter when it comes to the operation of the gun.

I'm with Gatorhunt, run it without the retainer in place. If you keep it in place the buffer won't be able to strike the carrier on the final forward movement which will negate the effect of the buffer's weights.

If you want to double check to make sure that is the problem, use a new buffer without the retainer and see if the marks develop. Or, cover the existing marks on the buffer with a thin coat of white paint or white out. Fire it without the retainer in place. If the retainer was the problem the paint should remain intact. If the retainer wasn't the problem the paint should continue to get chipped away and you will have to look for something else causing it. I think you will find the paint is not disturbed though and the cause is the hole being slightly off.

Anyway, good job on the lowers and enjoy them.
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