I have made a short barrel in 9mm for a customer that cycles with factory ammo.Barrel is 10" using the gas system.The gas tube is about 3 inches long and straight.Spring is normal but buffer is 9 oz.Just to see how much umph it has.Blank is special tight bore in 9mm.With heavy spring and 9 oz buffer it cycles with can but not without it.So how far can you go? You need custom gas block and short gas tube.Barrel nut was different.

My next project is to take the evo barrel and figure out how short it can go, I've got 2 gas ports(third is plugged) to play with in 2 positions. I'll start at 6" and work down from there.

I've been considering doing a DI 9mm like TP555 is talking about, I've got some 9mm blanks that need cutting. I think that with 9mm you'll be required to shoot handloads.

Jon

Just finished my 8" 300/221 build yesterday, bought the barrel from spook he posted about previously in this thread. m4 upper 16 bolt/carrier and a yhm spectre handguard. Should be fun once my new scope comes in !

crap picture, but here is the one with the 8" barrel by spook. m4 upper, 16 carrier, yhm diamond handguard "spectre" swr 300 can, pof sbr lower milled for a rdias, magpul ctr stock and miad grip, waiting on a scope and then will break out the chrony for some 200-220 load development.

http://img.photobucket.com/albums/v7...00221upper.jpg

Here is the one I built for a friend.

looks good, did he have any issues cycling? also got my scope in along with my bipod adapter today! should work up a load this week if i get a chance!

I'm sneaking up on the port size for him so he has a better chance at running supersonic rounds, last time we were out(first stab at the port diameter) it ran 75% lock back so I opened it .004". It should run now. I was running AA#9, he will be running W296 so it should work where it is, if not I'll open it again. I have mine running with 2 different gas lengths, both cylcle with authority.

Jon

Cool, thanks! I will be using h110 since i have 5 ponds left and if it works then i will stick with it. If not then a trip to the store to buy some AA