XL650, 300 BLK, AA #9 powder, Part #2 - Range Report, Preliminary

[7SFCW4]

So, if you read my earlier post, you know that this is an analysis of the 300 Blackout loaded using AA #9 double base, pistol powder. The prior report was an analysis of the loading and case prep, this is the first of two (at least) range reports. No Chronograph results, calculated velocity at 14.9 grains should be approx 2k/fps

AA#9 - 14.0 grains:

RECOIL: Very low recoil, accuracy at 100 meters was within two inches from the sitting US Army position.
CASE PRESSURE: Cases showed zero deformation.
PRIMER PRESSURErimers showed no signs of excessive pressure.
CASE, BASE PRESSURE: Base or cases showed zero signs of pressure, the L & C for Lake City were well rounded lettering.

AA #9 - 14.3 grains:

RECOIL: Very low recoil, accuracy at 100 meters was within two inches from the sitting US Army position.
CASE PRESSURE: Cases showed, remodeling of the shoulder area. The cases were being "...fire formed...".
PRIMER PRESSURErimers showed no signs of excessive pressure.
CASE, BASE PRESSURE: Base or cases showed zero signs of pressure, the L & C for Lake City were well rounded lettering.

AA #9 - 14.5 grains:

RECOIL: Very low recoil, accuracy at 100 meters was within 1.5 inches from the sitting US Army position.
CASE PRESSURE: Cases showed, remodeling of the shoulder area. The cases were being "...fire formed...".
PRIMER PRESSURErimers showed no signs of excessive pressure.
CASE, BASE PRESSURE: Base or cases showed zero signs of pressure, the L & C for Lake City were well rounded lettering.

AA #9 - 14.9 grains:

RECOIL: Very low recoil, accuracy at 100 meters was within 1.5 inches from the sitting US Army position.
CASE PRESSURE: Cases showed, remodeling of the shoulder area. The cases were being "...fire formed...". Cases still would fall free from the Wilson Combat GO / NO GO gauge. This is very telling from a pressure perspective (or the CMMG barrels chamber is factory tight??).
PRIMER PRESSURErimers showed flattening, no excessive pressure, no signs of the primer melting and flowing back over the firing pin, no signs of "...pig tailing..." like on .40 cal brass.
CASE, BASE PRESSURE: Base or cases showed the beginning signs of pressure, the L & C for Lake City were distinct, as if the case base was being pressed against the bolt face under pressure.

Bottom line. Next range outing will be loads in the 15.0 ~ 16.0 range, looking for: (a.) accuracy degredation; (b.) excessive pressure, primer metal remodeling, melting, flow back over the firing pin, etc...

SUBJECTIVE ANALYSIS: AA #9 works well, is available. Barrel, bolt, carrier and barrel extension showed almost zero "...spooge...", very clean. One pass with some CLP, and a few follow up patches yielded a clean barrel.

For range report #1, I highly recommend the 300 BLK, carbine length barrel, AA #9 at 15.0 grains.

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[KalamaMark]

Did all loads function in the AR, bolt holdback work on last round,etc?

Did ya get all the quirks ironed out loading 300 blk on the XL650?

Thanks!

 

[7SFCW4]

Did all loads function in the AR, bolt holdback work on last round,etc?

Did ya get all the quirks ironed out loading 300 blk on the XL650?

Thanks!

Good Morning, Terminal performance and function are flawless with the 13.9 ~ 14.0 grains of AA #9. The action was impressively clean (some other powders have been much dirtier in testing). I am reading ammo for testing in the `4.0 ~ 15.0 range now. Bolt hold back, etc...worked as designed.

No update yet on the XL650, for now, I am not using the auto case feed system, and loading brass via the clear plastic tube only.

 

[FarmerTed1971]

Looks like 14.5 might be the sweet spot.

 

[Velillen]

Nice to see this report! I was wondering about using aa9 but went with 5744 instead since it had load data available already. Be curious to see how aa9 does with supersonic and subsonics