Originally Posted by
Parabuteo
Del.
Dont dick about with the OAL and the load at the same time mate. Both will affect the group size, so you wont know what made things worse...if they get worse.
Looking at you loads I would say you have a reasonable amount of room for adjustment. I am shooting 77s over a compressed load of RS52 at 24.6. I am not suggesting you just go and do this, but most of us would see 24gr as a good point with 77gr SMK, so you have a way you can work up to mate. This fairly well replicates the M262 Mod 1 Blackhills match 5.56 loads.
Because we use mags, we are stuck with mag length (you can hand load but for CSR this wont work). However, the excess length has to go somewhere so it ends up compressing the powder in the case. There are some thoughts that this MAY produce a more consistent burn, I dont know, but certainly I have never had any adverse effects.
When you are stuck with mag length, you may not be able to produce the ideal distance off the landes. The main reason to do this is to arrest the bullet momentarilly to allow a peak pressure to build and give a more consistant let off point and harmonic. It is why some of the BR farternity soft seat (allowing the bullet to touch the landes and move back into the case rather than jamming into it).
In many ways this is good news, because it means you only have to mess with the load, however, you may also find that your group reduces in size if you factory crimp the bullet into the neck. This has a similar effect to loading into the landes, and you can be quite harsh with the crimp as it should not cause any issues (Lee's words, not mine). I crimp all of my calibres and have had groups improve with all 3.
Dont feel that you need to crimp, all I am saying is that there is no ideal 1 size fits all load workup, even 2 identical rifles made at the same time may differ. A friend of mine is about to shoot in a pair of identical BAR15s to it will be interesting to see how it goes.
Reply With Quote