PDA

View Full Version : help!!!! buffer weight damage on my ar15


mdib870
07-05-2012, 11:07 AM
i seem to be getting small nicks from my buffer weight smacking my retaining pin is there any way to fix this

bcm carbine upper
bcm bolt
80% tactical machine lower
utg milspec bufffer made in usa
no name lower parts kit

i wonder if its my front take down pin as it has a little play in it?

AK all day
07-05-2012, 11:11 AM
Could be the UTG tube, I have heard of problems with these.

tonyxcom
07-05-2012, 11:24 AM
Sounds like an out of spec Bolt carrier actually. The position of the buffer retainer is determined by the lower receiver. If the carrier is too short it could be allowing the buffer to slap the retaining pin when the bolt goes into battery, which has nothing to do with the receiver extension (buffer tube).

jsipe007
07-05-2012, 12:17 PM
Did your 80% Lower already have the buffer retainer position machined?

Arson
07-05-2012, 12:26 PM
Don't know how to link to the post "AR-15 Buffer Issue"
click in the OP link in the photo. Hope this helps.


Whats goin on here? Is this a real issue? This a Barrett Rec7 with a UBR stock. I'm debating sending it back to Barrett.

http://farm9.staticflickr.com/8014/7369295098_4e745c7ec2_b.jpg (http://www.flickr.com/photos/chriswakefield/7369295098/)

SocomM4
07-05-2012, 12:42 PM
Thought we already covered this??


Bcg was too short? I remember that the Bcg wasn't flush with the end of the upper...

Munny$hot
07-05-2012, 12:48 PM
Sounds like an out of spec Bolt carrier actually. The position of the buffer retainer is determined by the lower receiver. If the carrier is too short it could be allowing the buffer to slap the retaining pin when the bolt goes into battery, which has nothing to do with the receiver extension (buffer tube).
Examine the tail end of the bolt carrier when it's fully seated in the upper receiver. It should be flush with the upper

mdib870
07-05-2012, 12:56 PM
yes the retaining pin was pre drilled on the lower the tube seats fine up against the pin and the bcg is flush with the upper

tonelar
07-05-2012, 1:04 PM
What kind of pins are you locking up with?
Is there play frt to rr between your upper n lower? Side to side is no problem. Do you have one of those tightening wedges or an adjustable free play screw in your lower?

mdib870
07-05-2012, 1:05 PM
the rifle has less then 50 rounds through it .......the takedown pins are some no name ones that came with the lower parts kit as for the trigger and hammer pins those are kns

tonyxcom
07-05-2012, 1:09 PM
When you assemble the upper to the lower, put the front pivot pin in first.

Then pivot the upper down to the lower. Once they meet, you should feel some resistance as the bolt carrier presses the buffer OFF of the retaining pin. If it doesn't, something is out of spec.

I would try another BCG first.

Look at this picture below of one of my lowers. Do you see how the buffer is visible past the edge of the lower? Does yours look like that? That is the amount that the BCG should press the buffer in when assembled, so you end up with a mil or two of clearance between the buffer and retaining pin. The other possibility could be the retaining pin hole was drilled too far forward causing the same net effect of a short BC.

http://www.dromophotos.com/photos/i-FKLTKn2/0/L/i-FKLTKn2-L.jpg

jsipe007
07-05-2012, 1:11 PM
is the buffer UTG as well? or just the tube?

jsipe007
07-05-2012, 1:14 PM
Also, could the buffer retaining pin be out of spec?

mdib870
07-05-2012, 1:18 PM
the buffer does stick out like the picture and when i mate the upper to the lower there is some resistance like how you talk about but its not clearing the pin

mdib870
07-05-2012, 1:29 PM
everything i bought came from reputable companies the only thing i went a little on the cheap side was the lower parts kit "gun show special" the only thing that concerns me is the take down pins could this be whats causing my problems because there is some play when the takedown pins when they are seated and i mean just ever so slightly

tonyxcom
07-05-2012, 1:33 PM
Is the play fore/aft? meaning you can slide the upper forwards and backwards in the lower?

mdib870
07-05-2012, 1:42 PM
yes ever so slightly maybe .010 or .005 of an inch

tonyxcom
07-05-2012, 1:44 PM
I doubt that is enough to cause your problem, but it wouldn't hurt to change them out.

mdib870
07-05-2012, 1:51 PM
it used to be a whole lot worse before i changed my bcg its no as bad as it used to but id like to keep the service life of my ar......its my first ar15 let alone my first 80%build... I've had previous exposure to machining as i took milling as a class in college .....just trying to work the bugs out

Arnelcheeze
07-05-2012, 3:47 PM
what action spring are you running?

BenHa
07-05-2012, 3:58 PM
:useless:

mdib870
07-05-2012, 4:33 PM
just a standard weight action spring

mattt
07-05-2012, 4:44 PM
Had same problem when I put my w/o upper on my rock river lower.Had w/o upper on a spikes and no damage but wieght got chewed up on the rock river. I ended up adding tubbs wieght to rear of bolt and it pushed the buffer wieght off pin. Your pin is tapped to far back .

clutchy
07-05-2012, 4:50 PM
I'm seriously not trying to be a dick here but WTF would you go out and get a BCM upper and put piece of **** UTG crap in it?

mdib870
07-05-2012, 7:49 PM
I'm seriously not trying to be a dick here but WTF would you go out and get a BCM upper and put piece of **** UTG crap in it?


calm it down its my first build i just wanted to get it up and running and for only being 20 years old id say I'm doing a pretty good job with my build i even did a trigger job on it by myself and if you haven't noticed i live in stockton which at any time could turn into something like the L.A RIOTS if given a chance

THIS BUILD WAS PAID FOR COLLECTING POP CANS FOR 3 YEARS :D

bohoki
07-05-2012, 8:52 PM
there is a fix where you can take your barrel off file the front of the upper a tad and then replace the barrel it will have set the carrier back a tad

mdib870
07-05-2012, 9:08 PM
id like to say thanks for the all the input its helped out alot

mdib870
07-05-2012, 9:10 PM
there is a fix where you can take your barrel off file the front of the upper a tad and then replace the barrel it will have set the carrier back a tad

hey best piece of info I've heard all day i think i might take the upper to the local gunsmith and have this done this makes a ton of sense

shadowofnight
07-05-2012, 11:06 PM
there is a fix where you can take your barrel off file the front of the upper a tad and then replace the barrel it will have set the carrier back a tad

Just remember, the barrel extension is going to be deeper into the receiver, causing a lip at the transition point...probably not a big issue with a standard barrel extension...but it would be terrible on one with M4 cutouts.

Just make sure you blend in the M4 extension with the receiver lead in if you do this, you want a smooth/seamless transition from receiver lead in to barrel extension( Just 2 minutes with a cone shaped stone dremel bit, but dont forget. )

mdib870
07-05-2012, 11:14 PM
and yes this rifle was paid for by recycling cans and saving spare change

TNP'R
07-05-2012, 11:21 PM
and yes this rifle was paid for by recycling cans and saving spare change

Damn must of took you a long time.

mdib870
07-05-2012, 11:24 PM
3 years of collecting cans and small change a lot of ppl drink at golf courses ....one utg i don't notice the difference its still made in the usa thats all that matters the recycling company pretty much paid for most of my ar15 and i helped the environment so its a win win ill work on getting this problem fixed its gona take a bit of work if i decide not to take it in to get it done

mdib870
07-05-2012, 11:43 PM
the picture isn't my actual buffer but i do have wear close to that on my buffer obviously not as bad

mdib870
07-05-2012, 11:48 PM
ill try shaving a shaving a little off the buffer retaining pin and changing out my front takedown pin if those 2 don't do the trick ill have resort to the barrel its basically like reseting headspace in a sense

Arnelcheeze
07-06-2012, 12:55 AM
just a standard weight action spring
you're positive its a carbine action spring?

mattt
07-06-2012, 4:35 AM
Go to David Tubbs website order bolt carrier wieght system .It will push your buffer back off pin and it will make your ar more accurate 50$ It fixed same problem on my lower

mdib870
07-06-2012, 8:48 AM
im positive its a carbine action spring and I'm positive its impacts from the buffer pin the damage is similar to the picture above i don't have a image hosting sight so yeah...

mdib870
07-06-2012, 8:58 AM
Go to David Tubbs website order bolt carrier wieght system .It will push your buffer back off pin and it will make your ar more accurate 50$ It fixed same problem on my lower

hey matt thanks ill look into that if not i was also looking at the jp enterprises
silent capture spring as you don't need the buffer pin

ScottsBad
07-06-2012, 9:07 AM
Looks like the bolt is slapping the retaining pin INTO the buffer. Something is out of alignment or poorly machined.