First go with the 300 BLK

[Brad]

If i could learn to get a consistent cheek weld the rifle will shoot.
This was with the same bullets as before but heat treated at 425 °F for an hour then quenched. Harder does help in this case.

Load was FC brass, Rem 7 1/2 primer, and 10 gr of I4227. Recovered bullets are bananas just like the air cooled.

 

[300BLK]

I do NOT find ARs particularly ergonomic or easy to shoot accurately/consistently.

 

[Ian]

Getting better, for sure! Are those loads for certain subsonic?

I love that FC brass, the necks are thick enough and the state of anneal is correct and uniform.

Looks like the holes are pretty much round and it wants to group, I may have to try some toughened-up bullets just to see how they do accuracy-wise. Funny how heat-treated low-antimony alloy Brinell-tests a whole lot harder but when whacked the alloy is almost as mushy as air-cooled.

 

[Brad]

I need to chronograph to make certain they are subsonic. I can assure you there is not a loud crack on firing. If I shoot again tomorrow the chrony will go along.
A brake would almost allow a guy to watch impacts. Recoil is low enough to allow rapid acquisition of the target after firing.

 

[Ian]

With a suppressor it's like a horizontal pogo-stick. Very little muzzle rise and it's easy to watch the impacts through the scope.

 

[Brad]

Took the chronograph out today.
NOE 230 PB, heat treated at 425 range scrap, SL 68 lube, FC brass- new, and Rem 7 1/2 primers
I put 20 over the crony and got an average of 1075 fps, SD of 12.9
Based on temp, 35 F, the speed of sound is 1090 fps. I did have 3 shots over that velocity. I noticed no difference in report.

I may well be borderline transonic. I may reduce powder charge .2 gr or so and see if I can keep the average closer to 1050 fps.

I used a different rest, just a bunny ear bag on a hunk of wood, and it seemed to make things group a bit better. I think some of this is because I was able to sit more upright and it made for a more consistent cheek weld.

 

[Ian]

I had a few pop supersonic when using AA1680 at around the same velocity because the ES was so wide. I agree you might improve things by backing off a little teensy bit on the powder charge. Were your cases obturating the chamber well? That SD is pretty darn good for a low-pressure load.

 

[Brad]

Cases show soot pretty well down to the head. According to Hodgdon the pressure is over 30K PSI. They show 37K with a 230 jacketed.
They list 10.2 as max, I am at 10. I will try dropping to 9.5 and slowly work up from there.

 

[Ian]

I wonder if that powder is too slow for the pistol-length gas system. Not that dirty brass is the end of the world, it's pretty much unavoidable when using a suppressor on one of these and mine groups great at 100 yards with or without the can. Brass is quite clean unsuppressed, though, using RX7 in my pistol-length system.

 

[Brad]

I can easily go a touch faster. I have lots of 2400 on hand. I could also try some N110.

 

[Ian]

I'm not up on my VV powders. 2400 might be too fast to work the action, but I never tried it. If 4227 shoots straight and doesn't gum up the works so much that you have stoppages, then I think Bass would have something appropriate to say about that, but you know me, always looking to perfect good 'nuff.

Did you ever get a wet tumbler for cleaning brass? I can't remember. Tonight I deprimed and cleaned a couple hundred gummy black cases to shiny new in an hour, no worries about the soot or sticky SL-68.1 coating. Did I mention that soap lubes come off of the brass really easily with a minimum of detergent in a wet tumbler?

 

[Brad]

I did get a wet tumbler. It is nice to get the grunge off so easily. I am probably using too much soap bit other than needing extra rinse time it doesn't seem to hurt anything.
N110 is similar in burn rate to 2400 or at least in that ball park.

 

[Rick]

On this Hodgdon burn rate chart 2400 is listed at #54. N-110 is #60.

Hodgdon Burn Rate Chart

 

[Brad]

Thanks Rick. Just what I was gonna go look good for.

If I wasn't hoarding my WC820 for 357 mag loads I would try it. Like the N110 it is generally a little slower than 2400 but faster than H110 and much faster than 1680.

Ian, the 4227 burns pretty clean. I never see unburned kernels in the action or bore. It seems to be in it's happy place pressure wise for a good, clean burn.

 

[Rick]

I've never heard of H-100?

I tried 1680 in the 357 revolver, it actually worked fairly well but ran out of powder space before reaching the desired velocity. I considered redesigning the RCBS 180 silhouette bullet to move the crimp groove to allow seating it out a bit further. One more grain of powder and I would have been there.

 

[Brad]

Fixed my typo.

For now I will keep playing with 4227. I have lots of it with no other uses.

 

[Ian]

Obviously the 4227 likes what you're doing with it, 12 SD for 20 shots using plain-base bullets is a pretty good indicator. If you had a carbine-length gas system I bet the brass wouldn't be getting sooty.

The SS pin media tumbler is one of my favorite reloading tools, not sure how I lived without one all this time.

 

[waco]

I have a nice big Thumbler's Tumbler but my wife won't let me use it for brass. Tumbling rocks only!

 

[300BLK]

NEW 300BLK brass, $14.99/100 http://www.sagesreloadingsupply.com/index.php?route=product/product&path=60_80&product_id=399

 

[minmax]

Thanks for the info. I just received my order from them, only I ordered the Gemtech brass @ $15.99 per 100.