My newest 'no ban' toy is a 7.5" Model 1 AR pistol. I took it out for the first time today and it wouldn't run worth a darn. It seems to be failing to eject all the time. I'm not sure if this is common on AR pistols, but I can't really figure out why ejecting would be any different than a rifle. For the 10 rounds or so I fired it had no problem with extraction, that was my bigest concern with the short gas system. And it had no problem with the bolt going back far enough to pick up a new round. One test I did was load one one round in the mag and when I'd shoot it would lock the bolt back on the empty mag but the spent case would still be sitting on the bolt.


Kevin

I think you should ask this question in the Full-auto forum, some of the guys there have experience with short barrels.

I have the same kit and the same exact problem! I called Model 1 sales and they told me to send it in to them and they will work on it. They were very cooperative!

I hear that the 7.5" uppers have this problem......

I ordered the 11 or was it 10" for the pistol (long for pistol isn't it).... any how, I hope not to have an issue with it....

ejector, check it

then you may wanna add to the size of the gas port a thousandth or two

I have run into this very often and one of the things that REALLY helps is a heavier extractor spring, either from Wolfe or the mil-spec "black" spring and buffer.  Also with short barreled AR's you MUST keep your chamber very clean.  Any gunk build-up will cause the empty case to want to stick and slow down the cycle process.  A short barreled system is very finicky and must be kept clean.  We have had limited success by opening up the gas port, they are usually already pretty large and I would not go beyond .090" as you will then over power the cyclic which can lead to other problems and you cannot re-drill the hole smaller.  Since you state that you have eject problems and not extract, you can also check your ejector spring and try clipping a couple of coils if you have extra ones.   Another trick we have tried with limited success is to place a small ball bearing behind the ejector spring to make it stiffer.  But I would go with lightly polishing your chamber and increased extractor spring/buffer first.