300Whisper in the AR-15
 

I am trying to find subsonic loads for the Model-1 300-Fireball kit I have Built...
I have tried a couple listed loads and they will not cycle..
I need to run the 168 and the 220 grain bullets for starters..

Does anyone have this running??? Thanks...

Is it carbine gas port position? List the Loads you have tried. The 220gr should be no problem, but the 168gr will unless it is in pistol port position. Sierra list data for 1680, a sure deal and slow burning powder. If you have Win 296 or Lil-Gun on hand, these should work, but are faster burning and a little quieter.

Sorry I guess that would make a difference wouldn't it....

The AR-15 is a 16" barrel...
Gas stock system with a JP adjustable gas block....

The laods I have wouldnt work I didnt write them down or where
they came from because they didn't work... ha ha...

Check the gas port size. I got 1 in the shop the other day that had a .223 gas port. We had to open it up to get it to function.

That may be so ...What size should the port be drilled to???
What size is standard .223???
I know the company advertises that it is a 300-Fireball which is
super-sonic, but I need it to cycle sub-sonic..
We tried hodgdon 110 but it is blowing unburned powder
into the lower and causing a dirty trigger group but it will cycle...
I just need to know what to try next..
I am about ready to give up... HELP!!!
:confused:

I had difficulty using H110 in my M1S upper. It wouldn't work well with the 220gr pills and not at will with lighter bullets. I switched to AA1680 and had 100% with 220gr and about 90% cycling with 150gr bullets.

Ok great!!!

Did you have to drill the gas port??

I was looking at pushing the 168 gr nosler's...
What is the load data I should try with this??
Does it burn clean>>???

The 1680 burns pretty clean, not much different than most powders. My upper is completely stock from M1S. I haven't changed gas port or anything like that.

ok thanks..... I have been moving around the site reading &
and learning about my new toy. I have yet to find reload
data to try. any place on the site that will tell me exactly
what to try? thanks for the help.

We opened the gas port up to .120. Carbine port position. If I remember correctly the original port size was .069.