New build and not locking the bolt back?

[mustangfreek]

hey fellas, finally got one of my latest builds out today to see how it shot and to sight in the Aimpoint pro.

Well first off gun chambers, ejects and everything fine, just wont lock the bolt back on the last round, no matter what mag i used today. Which was a

Gen 2 20 & 30rd Pmag
Gen 3 20rd Pmag
Lancer 30rd clear AWM

Also im thinking i have it narrowed down to a couple possibilities, as here is a brief break down in the upper/lower parts on this build

rainier NIB bcg- which was tight out of the package new, tight i mean bolt turning wise
Spikes st-t2 buffer with std carbine spring
Seekins textured bolt catch

I am thinking the bolt catch might be to blame, as when it doesnt lock back the last round, i can see the seekins catch is still down and the follower of the mag is trying to push up but its bent..

Any info here fellas? Dont think its a buffer deal, but some of you are far more experienced with these that i am, again gun shot, functioned, chambered, ejected perfectly.

[UWone77]

I blame the guy who build that POS.

What kind of ammo were you shooting?
What kind of barrel ?

[Eric]

Verify it fails to lock back on an empty mag when cycling it manually as well? If so, I would ditch the Seekins part and use a mil-spec one (Colt part # is SP62301, $22). Double check that the correct spring is in place.

[mustangfreek]

I blame the guy who build that POS.

What kind of ammo were you shooting?
What kind of barrel ?


Whatever..it functions fine except the stupid bolt catch..lol

-A few different kinds of ammo, federal/ LC 556, pmc 556 and some winchester 556 , all 55gr stuff
-FN 16" CHF barrel



Verify it fails to lock back on an empty mag when cycling it manually as well? If so, I would ditch the Seekins part and use a mil-spec one (Colt part # is SP62301, $22). Double check that the correct spring is in place.


I have now had time to clean the gun and lower and inspect whats going on. It will not lock the bolt back on a empty mag by hand. with any mag i try.

What i have noticed is that between my other lowers (with std bolt catches) is this one with a milspec spring and seekins bolt catch is much harder to push in, not a lot, but noticeably different.

It is about the same looseness on the outside , roll pin side, but the inside part that slides up and down in the lower is tighter then the others and actually has wore off some anodizing on the lower of on thew rear side.

If you push the bolt catch strait in and out no problem, but when its even slightly tilted to the side it wont pop up over about halfway, played around with pulling up on it with my finger on the part the mag grabs and it does it everytime as the follower is coming up..

Should i take out the seekins and file the inside part some, different spring, cut the spring a tiny bit? or ditch it for a stock one, which i dont want to do, but will if i need to..

[GOST]

I've heard of some lowers having a to shallow hole for the bolt catch spring. You may want to take the bolt catch off and compare the depth of it to one of your other lowers. The guys that I've heard about having this problem just ended up cutting off a little of their spring.

[MoxyDave]

I've seen this before in an old Olympic Arms I had years ago. The bolt catch was a bit thick and had a burr that was making it stick. I pulled the bolt catch, filed a few thou off both sides, and it started working. I eventually replaced it because it was down to bare metal and I didn't want it to rust ...

So yeah, try replacing the bolt catch with a stock one. If that doesn't help try replacing the spring & plunger next. It's an easy test ...

[mustangfreek]

Pulled it apart, and the bolt catch is catching on the lower to where it has started wearing some anodizing off the lower. It works fine if you push on it from strait ahead but once the catch rocks to the back it is very hard for it to come up.

Dont know if maybe the hole in the catch is a hair too big or the body of the catch is a hair too thick? I contacted seekins for the hell of it, and he said he wants me to send in the whole lower..humm?

Gun works good, just this stupid little thing doesnt and bugs me , as i have a mild case of OCD when it comes to things i work on/build..lol

i dont have a spare catch or small parts on hand...i know i know..i should..Lol...i made a quick awesome video..okay crude and stupid video and sent it to one of the members here but havent heard back from him, as to what he thinks....[BD]

[Computalotapus]

I have a spare catch. I can send it with the smooth part of the afg I forgot to send ya

http://www.computalotapus.com/images/parts.jpg

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[mustangfreek]

I have a spare catch. I can send it with the smooth part of the afg I forgot to send ya

http://www.computalotapus.com/images/parts.jpg

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You the man, sent ya a message

[Computalotapus]

roger that will put it in a priority envelope tomorrow..

[mustangfreek]

roger that will put it in a priority envelope tomorrow..

Got it today, bud, havent had the time to mess with the gun, hoping tomorrow i will. Actually contacted seekins/ glen right when this happened and he offered a new one, so gave him my info and not sure when i will see it, but plan to figure this out one way or the other.

Thanks again jason , thats what i love about forums like this, people helping people.. Thumbs up!!

[Computalotapus]

Got it today, bud, havent had the time to mess with the gun, hoping tomorrow i will. Actually contacted seekins/ glen right when this happened and he offered a new one, so gave him my info and not sure when i will see it, but plan to figure this out one way or the other.

Thanks again jason , thats what i love about forums like this, people helping people.. Thumbs up!!


Man this community has given so much, anything I can do to contribute and give back. I have met some awesome people, bloggers, manufacturers, and fabricators. All of them are very humble people who will sit down have a beer with you and give you the shirts off their back to help you and your cause.

And it all started here.




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[jjl103]

I had a similar issue with my Seekins Bolt Catch... It was getting stuck on the upper (didn't have clearance on the top). Might want to see if it is rubbing anywhere externally.

[mustangfreek]

Ok , back to this ...help..long post , but i am getting frustrated..please read and let me know what you think, as if im am on the right path or?

I got a stock bolt catch from Computalotapus and already had glen from seekins offering me a new seekins one to try out, so just got the new seekins bolt catch from them today so decided to screw around with this.

Well installed the oem part and have some dummy rounds laying around and proceeded to try out gen 2, 20 and 30rd pmags, gen 3 20 and 30 pmags and a lancer awm. Well it would cycle about half the time and woud never lock it back on the gen 2 20's , as thier spring seems much weaker.

So swapped back in the new seekins catch and same thing, some mags worked flawless and others would hang up here and there.Hummm..

So i grabbed my other new build that hasnt been shot yet, that has a stock catch , and loaded up the dummy rounds in all the mags again, with this lower - mega, rainier upper and their std. black bcg and it cycled every one of them perfect and always locked the bolt, no matter what mag..

Okay..So i step back for a minute and rack the other gun a few times and then the other new build and can notice that the new, never fired gun racks much easier with the std, rainier black bcg , with a PSA carbine buffer and spring.

The build i am having issues with is using a spikes st-t2 and their spring.

Well for shits and giggles i swap out the rainier NIB bcg with the std RA bcg and load up my dummy mags in the first gun and it not only locks the bolt back with no problems, but i can physically tell it racks much easier..

I am thinking something is up with the rainier NIB bcg? I know a month or so before i got it they had a problem with a batch and had many people swap them out..Maybe the coating is a hair to thick?

Sorry so long, just frustrated and not sure where to go next, beside contact rainier arms and see what they say

[Judicator]

So it with the standard BCG it'll lock back with ALL mags? And the nibx one won't? If I read that right I would assume it's the BCG. Before that I would take the nibx one and put it in a rifle you KNOW works. If the rifle stoa working then I would call RA, get a new one.


Sent from my IPhone, please ignore spelling mistakes. Siri is dumb.

[Computalotapus]

Yeah I would put the weapons back to their standard configs and just swap the bcg. This way you can narrow it down to just the bcg.

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[mustangfreek]

ya , i will do that today and see what happens.

[UWone77]

ya , i will do that today and see what happens.

Sounds like you diagnosed your own issue.

Looks like you may have received one of their out of spec BCGs on one of their last batches.

[mustangfreek]

Sounds like you diagnosed your own issue.

Looks like you may have received one of their out of spec BCGs on one of their last batches.

Ya i thought so, but am now not sure what to think.

So i swapped BCG's between 2 of my AR's one is the RA NIB and the other is their std phosp. one.

So swapped them and played with some dummy rounds and wide variety of mags and had no problems, the NIB bcg seems to move easier in the other gun, and the other gun seems slightly dragg'ish again.

Then swapped charging handles to the original problem gun with the NIB bcg and put the fortis hammer NIB CH in it and it seems slightly better but still dragg'ish and had problems in gen 2 20 rd mags and 1 time with a gen 2 30, no problems with a lancer or gen 3 pmags

I contacted RA and they said they would swap out the bcg if necessary, but would just like to swap out the carrier, as i know this bolt is headspaced good to this barrel, and i would have to go barrel the tools again, and im about 2 hours north of rainier.

or should i just battle this and get some more rounds thru it?

kinda confused on which way to go.....My First ever build using spikes parts...runs better...[crazy]

[mustangfreek]

Anyone else have any info they might add?

im thinking either the carrier is slightly goofed up/maybe too thick from the coating? the bolt is pretty stiff when i manually try to rotate it when its out of the gun, harder then any of my other bcg;s i have on hand.

[UWone77]

Not much anyone can add until you shoot it with a different BCG.