My 4th 300 Whisper attempt

[ikorman]

Folks,

I have been trying (successfully and unsuccessfully) to setup a 300 Whisper platform. First one was some parts thrown together by Model1Sales for an AR upper. None of it worked. Second was a partial success story, using a switch-barrel Remington 700 also chambered in 223 and 17Mach4. I did not need the other two barrels and didn't want to keep 2 more scopes so I sold the whole thing.

Third attempt was a good one, albeit somewhat expensive: a local smith botched up a Rem700 rebarreling to 300 Whisper and I had to bring it to another smith that made it perfect. The gun came out sweet but I paid twice. Whatever! I am getting 1/2 minute groups with 220gr subsonic load and my YHM 30-cal can.

The last one: I had a couple of questions about it. I bought a used SSK Industries AR15 upper, 20-inch, A1 carry handle with the special adjustible gas thingie. I shot it today and had some mixed results: at first, it would not cycle so I cranked the the gas port all the wat up and it would eject brass but would not load the next round with 220gr subsonic load. I guess this was a short-stroke?

When I finally thought I should try it with a silencer for more gas pressure, it started behaving slightly better but not 100%. It would sometimes short-stroke and sometimes would do everything right, intermittenly.

Finally, I tried a 150gr 2100fps load and it worked pretty well. With the can and the gas port, it would cycle almost every time.

I really want to use the 220gr subsonic load. Otherwise, whats the point of 300 Whisper?

What am I missing? What should I do here? This setup seems to work much better than my first AR attempt and I don't want to write it off. AR15 in 300 whisper is too much fun to pass up.

[Gpz1100]

i took some weight out of the buffer first. then i had to clip off about 1/2" of the spring. cycles subs fine.

[dksd39]

if you are using an SSK chambered whisper you may have some issues feeding brass that has been cut down from 223 cases. The chambers from SSK are tighter than your average 300/221 chamber and can be picky about your brass. You may need to check your trim length and neck turn. Just some food for thought- good luck

[Alleycat]

I have a SSK upper and there is a couple of things about them. One is the chamber. I use reformed Winchester brass. I have .003 clearance. Tight for a AR, but enough. Second is the adjustable gas block. H= high velocity L= low velocity in between= off. What they don't tell you is that the thing gets clogged up bad. It should turn freely with a quarter. If it is not clean it will not move all the way to low. You get low gas volume BANG short stroke. Every time I shoot the gun gets a shot of gunblast and some work with a Q-tip.