I'm having a small annoyance with my new AR.  It's a Bushmaster lower with an LMT M4 upper, standard LMT bolt and carrier and an H-buffer.  After inserting a fresh mag and palming the bolt release the bolt/carrier travels forward, strips a round only about half way out of the mag and then stops.  Upon inspection nothing seems to be out of the ordinary.  The round is aligned with the feedramp and by simply pulling the charging handle all the way to the rear and then releasing the round is successfully chambered.  This only occurs every so often (1 out of 5 mags) and it only happens with the bolt locked to the rear.  

When inserting a fresh mag with the bolt closed and using the charging handle to charge the weapon everything goes as smooth as butter.  I thought maybe it was a mag related issue but it has happened with various different USGI mags and Thermolds.  My gun was generously lubed at the time so this shouldn’t be the problem either.  So far I have just under 600 rounds thru it of mostly Q3131A and a few mags of Wolf.  It has fed, fired, extracted and ejected 100% to date.

My guess is that for some reason the buffer spring isn't strong enough to accomplish the task at hand.  Does Wolfe (sp?) make a stronger carbine buffer spring?  I would like to get your guy’s opinions before I spend the money on a new spring though.  I appreciate any and all help.

You  proably have already,but have you tried differnt mags?

TG

00
Sounds like a fairly common problem with ARs.  Try loading your mag two rounds short of topped off.  30 round mag =28, 20 round mag = 18.  Many times a full mag will put too much preasure on the top round to allow it  to strip reliably from the mag.
MB

Try loading 28 rounds instead of 30 and see if it still does it. May be a mag issue.....

Wait...I thought we debunked the whole 'Load your guns two rounds short' myth?
Shouldn't the AR function fine with a fully loaded mag?
I can't help thinking that the 'load your mags a couple rounds short' advice was purely anecdotal, but I could be wrong. You'd think after 40 years of use and refinement the AR could handle chambering round on a full magazine.

Oh well, we'll see when the experts chime in as they always do.

Quoted: Wait...I thought we debunked the whole 'Load your guns two rounds short' myth? Shouldn't the AR function fine with a fully loaded mag? I can't help thinking that the 'load your mags a couple rounds short' advice was purely anecdotal, but I could be wrong. You'd think after 40 years of use and refinement the AR could handle chambering round on a full magazine. Oh well, we'll see when the experts chime in as they always do.

They should and they do.  My other two AR's perform this task 100%.  I don't even have to palm the bolt release.  I can press it with my thumb and they have yet to fail me.  This is however my first rifle that has a carbine buffer.  My other two use the rifle buffer and spring.

So does Wolfe make a +10% carbine buffer spring?

Quoted: Try loading 28 rounds instead of 30 and see if it still does it. May be a mag issue.....

I had to do this with my new Bushy.  Mags with fresh springs are tight.  Downloading by 2 is no myth, it works and is a good precaution.  

As a matter of fact, I'm gettting some Magpul followers so my mags will only accept 28 by default.

Are you holding the carbine steady and solid when you release the bolt?

Yes, I'm holding the weapon plenty steady.  I have two other AR's that work as intended with fully loaded 30 rounders.  I refuse to accept downloading by two as the answer.

I just looked at Wolff's website and it appears they make an extra power action spring for the CAR15/M4 series.  I think I will continue to shoot the weapon until it has 1000 rounds thru it.  By that point is should be plenty broke in and if it's still giving me issues I will upgrade to the extra power spring.  They are only $14.99 so it's not a huge loss if it doesn't solve the problem.

Thanks for the help.

There is never any reason to download a magazine.  If downloading a magazine fixes a problem with a rifle, then the rifle has the problem and downloading a magazine is just band-aid cover up solution for a more serious problem.


Scott

I'd also like to know why your using an "H" buffer?

Quoted: Out of curiosity, why are you using an "H" buffer?

Why not?  It's heavier than the standard carbine buffer keeping it closer to the original design and it slows the action down slightly to further aid with more reliable extraction and smoother cycling.  How can it be a bad thing?  

Quoted: Sounds like you've got all the answers already. Nevermind.

I mostly just pull shit out my ass and sometimes I get lucky.

Quoted: As a matter of fact, I'm gettting some Magpul followers so my mags will only accept 28 by default.

Who told you this? I have both the beta and production models, and I assure you they load thirty.

Incidentally, what makes you think the magpuls (if they did limit to 28) would be better? They're no taller than regular followers, so the only reason they'd not load more than 28 is because of spring tensions. Back to square one.

You need to read more. Real men load 30.