M16 9mm

[englishandy]

Just put my 9m upper together for my M16, and I'm having some problems.
I test fired a mag of 124gr. rounds through it a couple of weeks ago, and it seemed OK. Now, with the same ammo, it will only fire a couple of rounds before stopping. The extracted case is not getting ejected properly and stays in the receiver, so the next round gets hung up on it. I've tried several different magazines, all with the same result.
Any ideas

[vegassmg]

A single mag may not have been enough and sometimes the 9mm setups can be aggravating.

Help us out a little;
*What kind of buffer are you using?
*What kind of ammo?
*What kind of mag well adapter are you using?
*What kind of magazines?
*Has your bolt been ramped? Weighted?
*
The first two places I'd look is the ammo and buffer.

If you're using reloaded ammo, try a box of good factory ammo. Yea, it's 'gonna cost you money, but it's a simple way to rule out one problem. When I owned my Vector Uzi, it ran fine with the weak green or yellow box UMC 9mm ammo but not in my 9mm conversion. It consisted of an ASA mag block, with a ramped, unweighted bolt, 10" barrel in an early Colt receiver using an AAC rate reducing buffer. I'm sure you'd like to load one ammo for al your guns and that may still be possible. I found that my closed bolt setup required a hotter ammo than the open bolt guns but your experience may be different.

Buffers can make a huge difference in not only 9mm conversions but also when using short uppers where bolt bounce may be a problem. Typically a 16" or longer 5.56 barrel will run just fine at the ROF it generates. Shorter barrels run faster and require a heaver buffer. Most people find a heavy buffer is needed on the 9mm kits to get them to run well too.

[englishandy]

It has a MGI buffer, RRA mag well block and I'm using stainless steel mags from C Products. The bolt was ramped by M60joe.
The ammo is my 124gr. reloads that work fine in my Sten and Sterling.
I'm going out to the range later today with Matt Adams to run some more rounds through it and try and pinpoint the problem.

[vegassmg]

You sound good to go with the possible exception of weak ammo, (yeah, I know it runs in your other guns). The RRA blocks are known to have ejection/extraction issues. See if this information helps. www.jobrelatedstuff.com/forums/topic.html?b=3&f=15&t=355848

I bet I don't use my 9mm conversion once a year. You're welcome to borrow my ASA top drop in block if you'd like to experiment....

[englishandy]

Went out with Matt and he did basically what those guys were talking about on that thread. Dressed the angle on the extractor and adjusted the ejector closer to the bolt.
There's still a difference round to round with the ejection, but it's not hanging up like it was.
I'm going to up the charge in my reloads slightly and see if that helps.
Now I've just got to figure out why the bolt won't stay open with those C Product mags.
Thanks for all the info.

[vegassmg]

I'm betting you're ammo is too weak and that's the reason I suggested a box of factory ammo. If your bolt isn't being thrown back far enough, then the bolt hold open devise can't function and the problems you're experiencing could be a result of that.

I've seen the same problems in 5.56 with insufficient gas to the carrier due to weak ammo or a leak. No last round bolt hold open.