reloading 300 blackout for subsonic and supersonic

[300Blk]

Bryan Litz book has reverse-engineered Sierra 220 drawings that are not that far off.

Lil'Gun can maybe be made to cycle in a carbine, but you would need a maxed out gas port - and then supersonic would cycle too fast. It is one way to go, but not what I think is best. I am all about minimizing the difference between subsonic and supersonic.

[robpiat]

IMR 4227 works great. It gets no love, but has been very consistent velocity wise at any temp.

[silentbushmaster]

Case: 221 Remington Resized w/ 300/221 Redding Dies
Primer: Fed SR Match
Powder: VVN110
Weight: 18.0 grains
Bullet: 110 Hornady V-Max
OAL: 2.000
Barrel: 10.0 Noveske "Pistol gas system"
Speed: 2150 fps
Suppressor: AAC 7.62SD

Load is about 1.0 grain under max, max loads would blow about 2 out of 30 primers.

[imyomama]

I don't see why a faster powder wouldn't cycle a carbine action. Most faster burning powder would result in a slightly higher pressure. I suppose it could have to do with duration and dwell time. All supersonic 5.56 (and 300 BLK loads?) are high 90s burn rate in a 16".

Quickload shows that 8gr of Li'l Gun pushing a 240gr SMK through a 9" would result in 1010fps, ~78% powder fill and ~97% burnt powder, at ~27000 PSI chamber pressure. Seems like something like that would make more sense. But I don't have the upper or components to try right now.

On a somewhat different note. Does anyone have the measurements for the 220gr SMK? OAL, small diameter of taper and length of taper measurements.

hum.. I loaded 8.5 gr of lil gun 2 weeks ago and they all went supersonic on my 9" with smk 220's .. and didn't cycle the action..

so that blows that theory!

[silentbushmaster]

Barrel: Noveske 10 inch
Buffer: Regular with regular spring "Would not use a H buffer"
Magazine: USGI
Suppressor: AAC 7.62SD
Rail: La Rue 9 inch
Muzzle device: AAC 18 tooth break

Load Data:
Case: Remington 221 Fireball reformed to 300 BLACKOUT specs
Dies: Redding 300/221 "Correct to 300 BLACKOUT specs/ No crimp"
Powder: A1680 @ 10.9 grains @ 1000 fps "Average speed about 25 fps per 10th of a grain"
Started at 11.0 @ 1040 fps and went to 10.4 grains @ 850 fps and it began to have failure to feed issues at that powder charge.
Primer: Federal Small Rifle Match
Bullet: 220 grain Sierra Match King
OAL: Max @ 2.090 Min @ 2.085
Accuracy was below MOA with most at 3/4 MOA with 1-4 optic @ 100 yards.

[imyomama]

here is the vid.. one round supersonic.. 2 round sub.. 1 more supersonic .. the subs here are the 220 with 10gr of 4198 .. the supers are spitzer sierra and 18g of h110..
http://www.youtube.com/watch?v=ZPzHLj6C2YI

[imyomama]

Running this recipe (as well as Robs A1680 recipe) shows that it only results in ~70% burnt powder. Using something faster burning seems like it would make sense.

Then it wouldnt cycle in a carbine system. Im no scientist, well actually I am but biology doesnt count, but it seems pretty efficient.

quick video uploaded to youtube.. super h110 and subs.. using 4198.... check it out link on my thread..

[tctlrld]

I don't see why a faster powder wouldn't cycle a carbine action. Most faster burning powder would result in a slightly higher pressure. I suppose it could have to do with duration and dwell time. All supersonic 5.56 (and 300 BLK loads?) are high 90s burn rate in a 16".

Quickload shows that 8gr of Li'l Gun pushing a 240gr SMK through a 9" would result in 1010fps, ~78% powder fill and ~97% burnt powder, at ~27000 PSI chamber pressure. Seems like something like that would make more sense. But I don't have the upper or components to try right now.

On a somewhat different note. Does anyone have the measurements for the 220gr SMK? OAL, small diameter of taper and length of taper measurements.

hum.. I loaded 8.5 gr of lil gun 2 weeks ago and they all went supersonic on my 9" with smk 220's .. and didn't cycle the action..

so that blows that theory!

Granted, my recipe was for a 240SMK... but it looked promising in QL. I don't have the data for a 220SMK, but using a Sierra 220gr RN (2180) in front of 8.5 Li'l Gun doesn't look too promising from either a fill ratio or pressure standpoint. <20,000 PSI. Do you have a set of calipers you could take to that 220 SMK for me?

[imyomama]

i'll measure tonight... my goal is to set my dies once and then load 125's and 220's with the same setting ... so I don't have to keep messing with it .. my press has quick change heads , so I leave my dies set all the time .

the shape of the 220's make them stick out a little longer anyways..

well .. lil gun didn't work for me .. so the combo of being sightly supersonic and still not cycling the action makes me think it won't work no matter what I do to adjust ...

I'll load more 4198 for this weekend and do some accuracy tests this time (10 shot groups at 100 yards).

cool?

[imyomama]

BTW 10.8 grain of 1680 also worked perfect in my 9" .. just can't find that powder anywhere!