Cast in AR-15 , Bolt Not Locking Back

[mkm]

Shot some test rounds today, 55 gr. Cast. Used re-7 at 15.6, 16.0 and 16.5. All loads cycled fine, but none of the loads would lock the bolt back on the last round. Is this kinda normal shooting cast in an ar? Its not a big deal if it locks back or not, just wondering. Not sure if I want to up the load anymore, lyman manual shows 15.7 as max load for that bullet. No leading at all. Thinking of loading more at 16.0 gr. And check accuracy.

[nhrifle]

Re-7 does not, in my experience, produce enough gas volume and pressure at your load levels and a bit higher to get bolt lock. I had trouble getting proper function with that powder shooting jacketed. I would try a different powder. Try some IMR 4064 as I have had good luck with cast in that caliber.

[Jupiter7]

Most likely a lack of pressure at the gas port. Could be a bunch of other things too.

[dkf]

The bolt is probably not going back far enough. I don't know your setup but there are a couple fairly cheap things you could try just to see if you can make the load work. A reduced power action spring and/or a lighter buffer. Wolf makes reduced power springs and buffers are available in several weights.

https://dsgarms.com/wol16502
https://dsgarms.com/wol16505

[Reverend Recoil]

I had the same experience with RL-7 and my AR15. Try a slower burning powder that works at 20-26gr.

[Jailer]

Wrong powder speed for the given objective. Switch to 4895 and you'll have a lot better luck.

[mkm]

Thanks for the info. I do have 4895 on hand but wanted to see if I get the re-7 to work because I have so much on hand. I am going to load more test rounds to check accuracy and increase charge slightly and see what happens.

[smokesahoy]

Yep probably just too light a load. Those guns were meant to function on the higher end, it sounds like you are close though.

[fcvan]

When I first started shooting cast (Lyman 225-415) I used IMR 4227. The Lyman #49 recommends a max of 14 grains for an estimated 2190 fps, and 23200 CUP. This load shot and cycled well in my Ruger Mini 14. I have since built a few AR platfor rifles and they also shoot fine. For the past year, I have been shooting this boolit PCd with full function and lock back on the last round.

For the past 6 months, I've been playing with the AR in 300 blk, also using the IMR 4227. I like the versatility of this powder and I like that I have been able to get 8lb containers, the last one arrived last week. Some folks have been getting higher velocity with PC and different powders. I am quite satisfied with the loads I'm using. Tin cans die horrible deaths when shot with cast boolits.