ISSUES first time out...

[MOUNTIN DU]

Well... I finally got to zing some flextips down range today and although I'm very pleased with all the factory groupings (sub MOA) at 50yds from a sack of corn; I had some feeding "issues" with the factory & BM modified GI mags. Here goes...

First 5rds from factory mag; starting with an open bolt, went fine but the bolt didn't lock open on the last shot. When charger handle was pulled all the way back it locked against the empty mag follower like it should have done when the last shot was fired... dumped the mag and duly noted

Next, I reloaded the gun(closed bolt) with a BM modified GI mag with 10rds. It went home and locked into the mag well with no issues. When the charger handle was pulled all the way back and released, it picked up the first round and went home just short of "fully" closed. Bumped forward assist to close the bolt. Fired first 5rds... all 5 needed forward assist "bumped" to complete the cycle. Last 5rds functioned flawlessly; BUT, the bolt didn't lock open on the last round AGAIN. Dumped the mag. Reloaded, released the bolt and needed forward assist again for the first 5rds. The next two BM modified GI mags (10rds each) did the exact same thing!!! ...as well as the factory mag. Bolt never locked open on last round with any of the mags. Only when drawn back by hand did it lock open.
My son (brass catcher/spotter) noticed almost immediately that most of the ejected brass was scattered aimlessly across the ground with some very lazy ejects only traveling 2 or 3ft from the gun; some showing signs of sooting at the mouth, but fully compressed primers on all rounds... again, sub MOA groupings at 50yds! He suspected the ammo We were shooting between rain showers so I never setup the Chrony... but again; sub MOA at 50yds. The extreme spread couldn't have been that "extreme"!

That's when I thought about the M16 heavy buffer! He wanted to swap buffers from one of his AR's (5.56) that he brought along, but I was satisfied with the scope, gun & load combo so I declined. We checked the bolt travel and it is fine. The bolt has several .01's travel past the lock before the bumper hits the back of the spring tube

Any ideas?

[2zero6]

I had the same happen using a modified gi 30rd but ended up being feed lips out of spec rubbing the bolt.

[MudBug]

How well did you lube the bolt?

This could just be a case of a new rifle needing to break in. The finish can be a little rough on both the inside of the receiver and on the bolt carrier. Maybe try running it a little wet for the first little while.

[gunnut]

I had a similar problem with an AR 10. Turns out, The AR 10 takes a CAR buffer. Shorter.
I would put everything back the way it was out of the box and try it.

[2zero6]

I just looked at a pic of your rifle and noticed it has a collapsible stock are you running a m16 rfle buffer in the collapsible tube?

[MOUNTIN DU]

CAR length buffer & spring... M16 buffer looks identical to std buffer but 5/8 oz. heavier and stamped with an "H" on the face. Could the buffer tube be screwed too far into the lower loop causing a short cycle?

Mag lips don't seem to be dragging (no marks) on the mag lips or bolt. Although I did notice that if the lips are too far apart, they allow the top round to "ride" too high causing drag on the bottom of the bolt.

The bolt and carrier were oiled & left wet for the first time out. My son seems to think it just needs to be "broken in". Before we started shooting, he commented on the rough, stiffness of the new action & trigger. His 556 guns feel like glass and all he does is shoot the hell out of 'um. Of course he works at a gun & police supply store with a range!

@ gunnut; I think I'm gonna put the std buffer back in place and start over

I'm still very happy with the combo & accuracy of the factory rds

[gunnut]

Just like reloading. Only change one thing at a time. I do a lot of trouble shooting in my work and its always the same. Put everything back the way it was BEFORE the problem occured and take it one step at a time untill the problem happens again. Now you know what caused the problem! The last change you made!

[wildcatter]

Just like reloading. Only change one thing at a time. I do a lot of trouble shooting in my work and its always the same. Put everything back the way it was BEFORE the problem occured and take it one step at a time untill the problem happens again. Now you know what caused the problem! The last change you made!

Absolutely and as Mud Bug said...Lube, lube, lube, this is very common on any new AR that isn't lubed properly amd if you have changed the lower set-up, do as GN says.

This system is designed to work with all the standard goodies, stocks, buffers, etc. Hence being able to change from one companies lower to another and everything working just fine, provided the lowers, stocks, buffers, etc. are all standard setups. So if you are changing things out, looking for a different result, then you're into the "Tweaking-Zone".

Good luck, fear not, it'll run just fine as soon as you figure it out, or go back to a mil-spec set-up..

[MOUNTIN DU]

Sometimes I just can't help but out think myself so I humbly reinstalled the std buffer for my next shooting excursion. One step at a time and noting the changes as gunnut suggested!
I couldn't help myself so I tweeked the mag lips too, so that all the top rnds were at the same high and angle as the factory mag too!

[wildcatter]

:oops: Sometimes I just can't help but out think myself so I humbly reinstalled the std buffer for my next shooting excursion. One step at a time and noting the changes as gunnut suggested!
I couldn't help myself so I tweeked the mag lips too, so that all the top rnds were at the same high and angle as the factory mag too!

Okaay, but you're shooting yourself in the foot, as I have done maybe a thousand times. It's always important to do one thing and then the next and so on. We need to understand the problem and if you do ten things and that fixes the problem, well, what exactly fixed it, in the first place? Remember to lube that baby. If you are not sure, do the youtube thing again and try a search for say.. "lubing an AR-15" or some such. I use youtube allot for all kinds of things. If you want to see how to rebuild a particular kind of transmission, believe me, someone has it on the youtube and using it, we can get a major foot up on our next project. Which gets me thinking now, you guys reading this, what kinds of things do you want me to put on the youtube? I am going to do a movie on the kill bullet doing 6000rds at about 60,000psi, with witnesses, but there are a ton of subjects we could do, what are they? But don't load this string up too much, we still got to get the gun running, maybe another string is more appropriate..