I put together a 350 legend AR. My reloads I made on range pick up brass with a 147 grain Armscore FMJ-RN and Lil'Gun went well. Reasonably accurate and functioned perfectly.
But I only had 57 cases and what I ordered from Starline won't be in until mid to late July. So I bought 10 boxes of Winchester 147 FMJ. I mean it's cheap enough and the brass is OK so why not.
Why not is because it is seriously under powered. Every round I fire showed symptoms of under gassing. Second round would be a bolt over brass failure to feed and the last would drive the base of the round into the magazine and do a nose up jam. A lot of people would say that's a magazine issue but it isn't. None of it would lock the bolt back. All indications that the bolt wasn't going far enough back and needed more hang time. That and the bolt speed and recoil were both a good bit less than my handloads. But it was shooting 3 into 1-1/2" groups.
So, process of elimination, take the ammo apart. I found the inside a bit disappointing. A light gray dull ball powder like I've never seen. And then only 19.6-19.9 grains by my measure. Cheap, like low end former com block ammo. So I replaced it with 28 grains of H110 now I know I have taken the pressure factor out of the equation.
We will see
