300blk help

[cheese1566]

I built a 300blk AR pistol with a 9 1/2” barrel using a pistol length gas tube and adjustable block.
This unit will house my new titanium silencer using 60• cones.

I found my initial testing rounds using NOE 311-247 are not seating fully. They are sized .310” and the first driving band (seated after this at the crimp groove) is binding on the chamber cut just before the lands.

I do have a NOE 311-284 and a MP 312-159 I can try, these are gas checked and the NOE 311-247 is plain base.

I would like tohave this gun be subsonic to utilize the full potential of the suppressor.

Thoughts?

I do have CFE BLK, R7, IMR 4895, HP238, IMR4064, WIN748, WIN296 on hand...

[popper]

BO freebore /throat is about 1/2 the length of the neck with slight taper at the end. Keep seating deeper til the chamber or find a better fitting mould. CFE BLK (dirty), WIN296.

[cheese1566]

I really should have tested the seating before making any live loads. I usually do...

I was thinking of seating past the front drive band, and going past the crimp groove. Seating tests using a a sharpie to color the boolit, show it’s hitting on the front band. Might be why they don’t like Gen2 Pmags.

I was also thinking of sizing some to .309 and such.

This is all the development stage. The fun we do in the search of a great load!!

[popper]

BO freebore /throat is about 1/2 the length of the neck with slight taper at the end. Keep seating deeper till it chambers or find a better fitting mould. CFE BLK (dirty), WIN296. NOE 247 might work, nose may be too big. But HP238? HP38/WW231 works but won't cycle. Look for book sub loads. With pistol gas you may have the GB get stuck if you get gas cutting. Also watch the gas key port, I've had a build up there where the lugs don't lockup all the way. I would definitely PC the subs. Might try the 309 depending on what brass you use.

[45r]

I shoot the noe 311247 sized .310 over 8.8 grains viht n-110 in my 9 inch upper.
The best COL for accuracy and feeding has been 2.120.
You might want to size to .309 if you can't seat to the above COL.
If I try to seat farther out in my rem bolt gun it shaved PC on the front band.

[1006]

Seat deeper and try the RL7 or the 296.

[cheese1566]

Thanks guys!
I made some test dummys and seated it to 2.120". These function through the action with no hiccups. I loaded 15 with 11/11.5/12 grains of CFE BLK for some initial function rounds. Its nice that I can now possibly use my MagPul Gen2 mags as they clear the internal rib.

Ill have a winter project exploring the RL7 and WIN 296 as well.