I have a AR-15 from American Spirit Arms (Scottsdale, AZ).  About a year ago I purchased the 9mm Upper and Mag Block.  I luv the 9mm shooting (even better than .223) But.......

The dam gun jams ALL the time.  I get mostly the "stove pipe jams" where the spent case is still in the chamber with the fresh round but also the occasional fresh round only jam.

The ASA guys (I lived in Phoenix at the time) were real nice but couldnt solve the problem.  They told me to use a heavier bullet (i.e. no 115 grain ammunition).

Finally in desparation I called Rock River Arms to ask their opinion.  I took their advice and changed the hammer out to a 9 mm hammer and installed a 9 mm buffer.

I still get many jams!  I have try both 115 & 126 grain ammo.  The gun is clean and in really good shape.  I use good condition 25 rnd UZI mags with the only mod being the mag catch hole which I cut with my own dremel.

Any thoughts from out there in 9mm AR world?  I would really appreciate any suggestions.

Maybe try a factory cut UZI mag from RRA, or have someone like joeblack cut a mag for you and see if it works better?

Wrap tape around you mag so it's very tight in your mag well adapter.  Then, try to raise and lower (very little) it into various positions and shoot.  This will help you determine if you converted the mag correctly.

Jamming on the last round in the mag is common (if this is a issue for you)  You have to bend the legs on the follower so that the follower top (part that touches the round) is more perpendicular to the magazine.  In other words, minimize the angle the last round sits at when in the magazine.

Extractor seating correctly? Take a black magic marker and color the entire extraction groove on a few cartridges.  Shoot them, and see if the extractor is fully seating in the grove by looking for the marker to be rubbed off.  

HTH

Thanks for the thoughts regarding the mags vertical position in the mag well!  I will give it a try but I can describe my gun a bit more and maybe eliminate some possiblities.

Cannt go up.....the top of the mag is against the top of the mag block....thats the way ASA cuts theirs and told me to do it.  Regarding down, wouldnt the new round jam against the little ramp on the front of the mag block that guides the round up into the chamber.

The last round is not the issue its every round at any time.  But sometimes it goes through a whole speed shooting fast without a jam.  Maybe bending the "lips" down might help 'cause I have noticed that when the round is pushed out of one side of the stack it kind of pops out vertically rather than a smooth push forward.

Quoted: Cannt go up.....the top of the mag is against the top of the mag block....thats the way ASA cuts theirs and told me to do it.  Regarding down, wouldnt the new round jam against the little ramp on the front of the mag block that guides the round up into the chamber.

Only IMI 25 round mags can be fitted in the ASA mag well adapter this way.  32's and 40's can not. The 32's and 40's distance from the top of the feed lips to the front of the mag where the mag well stop goes is longer on these mags.

Are you using 25's?

Might try to contact Russ at Cavalry Arms.

They have a lot of experience making the pieces of shit that ASA produces work.

In the future do a search of AR15.com before buying anything.

ASA makes crap.

Yes I'm using only real IMI 25 round mags.  When I thought about it the ASA guys did have me decrease the angle of the follower.  It hasnt helped so far.  Also it seems that after doing the mod to the follower, I cannt get all 25 rounds in the mag anymore.

Thanks for the tip on Calvary Arms.  I have no special loyalty to ASA but I do thing they make a decent product, but I am very disappointed with the function of the 9mm conversion.

Ameetec Arms has a 9mm rifle that functions flawlessly.  Give them a call they might be able to give you a pointer or two.  Try the Winchester 115gr 9mm Luger.

The relationship between upper, mag block and mag is critical on the ASA's.  Mine on a early Cav worked great.... but I switched it to another Cav lower and it's acting up now.  I haven't taken the time to diagnose it fully, but what you describe (stove piping) is happening on mine.  I think the ejector has to be adjusted.... not sure if its' sitting in the groove right or high enough.  It's possible (in my case, the extractor spring is weak......) I've shot quite a bit out of it..... (115gr )

The last batch of ammo might have been weak.  Who knows.  I bought 1000 rounds of 9mm from a dealer buddy and ran out just recently.  The stuff I was using when it acted up was some stuff I got at a local shop (Winchester 115's), but I sware it was weak.... oh well.  Thought about getting some Seller & Belliot, but haven't had the time to track some down locally.  If it works w/ a different brand of ammo, then I know what the issue was, not enough "umph" to cycle the bolt back to eject (but far enough back to load...)  

My ASA 9mm upper woulnd't fit an AL lower (well, the one I tried.  Woudn't close).  Maybe I'll try it on another AL lower to see (that's why it went on a Cav originally).

Good luck on your probs...

Just to close this one out......

The problem was the mag block.  I bought a VM Hy-tech block, clicked it in and I'm happily banging away with no jams at all.

Shame on ASA for selling me an out of spec part!

When did ASA start selling anything in spec?