AR 16" barrel .223/5.56
In an effort to improve accuracy of the ammo I've decided to control shoulder bump and bullet jump. The measurements seem a bit...big.. but heres what I got, does this sound right?
I adjusted the FL sizing die to achieve a -0.004" shoulder bump compared to a fire formed case.
Next was bullet jump. Using the OAL gauge I made, and a 50gn lead-free varmint grenade bullet, I measured COAL with the bullet to the rifling. (A case with -0.004" shoulder bump was used)
I got a 2.310" COAL! Even if I wanted a 0.015" bullet jump thats 2.295" COAL which wont fit the magazines and is significantly longer than the recommended load data for this bullet, which is 2.200".
To reality check things, I did tests with the COAL at 2.305" and 2.320". At 2.305" the bolt locks in place with zero effort. At 2.320" it takes some slight finger pressure but it locks, although the bullet (when marked with a sharpie) definitely has rifling marks on it.
So...what do I conclude from all this? My goal is to make accurate ammo. Should I modify a magazine to fit these at 2.315" COAL and then develop a load? Is that even realistic at that COAL? I dont mind single-loading each round if need be.
note: the OAL gauge I made is pretty self explanatory. If you have a home machine shop its a fun project but otherwise I'd suggest just buying the $40 hornady OAL length gauge and the associated modified case