AR Sponsor
Posted: 11/28/2008 4:25:29 AM EDT
|
I have a new build that I just completed. Well last night I tried some mags to check feeding and with three different Okay mags the BCG failed to close the last .25 inch or so. I loaded an off brand shit mag and it loaded all the way and ejected all three rounds however it did scar the bullets pretty good. The rounds were TAP 55 & 60 gr and BH 75 OTM. Oh and the FA will not engage because its too far out of battery.
What I have built is a RRA upper and lower, Noveske 18" SPR barrel group, Young NM BC. SO I am asking is this just mag problems? These are tight fitting newly rebuilt mags. They all have green followers and wolf power springs. They were all loaded with 26 rounds instead of 30 btw. I have 10 Pmags on order and 10 C-products on order too. Ideas????? Po-Po |
|
Well, I'm excited to hear a real expert chime in on this.
We are talking about FTF using the bolt release, or pulling the handle back all the way, right? So, it closes without mags, and closes with some mag brands? What kind of round count out of this rifle are we talkin', <1000, >100k? Is the gun super dirty in the chamber? Does this gun have an M4 feed ramp upper with a standard feedramp barrel extension? The phrase scared bullets is making me think about that. I'm guessing either the mags are wacked out, or you have some kind of marginal situation, where the gun feeds normally, but new rebuild, good, mags throw this out of whack. First compare good mags to not working mags. If mag spring pressure is slowing the action down so much, it will not lock the bolt up, that means your action is moving too slow or is too lightweight. Weight can't really be f'd up by the owner, unless this is some high speed gaming BCG. So, I would guess there is too much resistance turning the bolt or maybe the recoil spring is wore out. (Can recoil springs be wore out?) I think after looking at the above things, I would inspect the bolt operating force, bolt cam pin for damage, and the carrier for carbon build up. |
|
Quoted:
Well, I'm excited to hear a real expert chime in on this. We are talking about FTF using the bolt release, or pulling the handle back all the way, right? Yes we are talking about both because I tried both So, it closes without mags, and closes with some mag brands? Yes it closed with an off brand mag that has no name on it but will not work with an Okay mag that has worked in two different AR's without an hitch. What kind of round count out of this rifle are we talkin', <1000, >100k? ROUND COUNT 00000. This is brand new. I was just function checking it before I took it to the range for initial break in. Is the gun super dirty in the chamber? No its sparkling clean Does this gun have an M4 feed ramp upper with a standard feedramp barrel extension? The phrase scared bullets is making me think about that. Yes M4 feed ramps all around. But it sure gouged the bullets in a rotational direction about an 8th or 16th of an inch near the plastic or ogive. I'm guessing either the mags are wacked out, or you have some kind of marginal situation, where the gun feeds normally, but new rebuild, good, mags throw this out of whack. First compare good mags to not working mags. If mag spring pressure is slowing the action down so much, it will not lock the bolt up, that means your action is moving too slow or is too lightweight. Weight can't really be f'd up by the owner, unless this is some high speed gaming BCG. So, I would guess there is too much resistance turning the bolt or maybe the recoil spring is wore out. (Can recoil springs be wore out?) I don't expect so but hell I will change it out today and see as an eliminator I think after looking at the above things, I would inspect the bolt operating force, bolt cam pin for damage, and the carrier for carbon build up. I looked last night but there was none evident. As to carbon that's a mute point at this stage. |
|
Carrier moving freely in the upper without the bolt, hence the gas tube aligned with the key, and the key not binding in the upper receiver track?
Bottom of feed lips on the mag, the end of winds on the recoil spring, and the buffer roll pin not bur'd or protruding causing problems? Head space checked to confirm that the chamber is in-spec with the give bolt? Also, confirmation that the mags are feeding correctly, and not low feeding (tip hitting the upper receiver below the ramps)? Furthermore, conformation that the barrel is installed correcty on the upper, hence the bolt can enter and exit the barrel lugs without binding? Upper well lubed for break in/self polishing of fresh/rough parkerized/anodized parts against each other? If an semi carrier, then the FP confirmed that it's the right unit, and not anlarger M-16 FP with the collar higher than the carrier ramp lip (read catching the hammer). |
|
Well I seem to have found the problem. It would seem that the bolt was sticking inside the barrel of the BC enough to slow the forward speed down.
After I worked on the bolt with a polishing wheel around the seals it cleaned up rather nicely and started feeding everything I stuck in there. I appreciate the suggestions. Po-Po |
AR Sponsor