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9/17/2012 9:32:15 PM EDT
Would anyone care to make a muzzle velocity prediction based on the following starting formula?

10.3" Barrel AR-15 with Pistol length gas
CCI Small Rifle Primer
220gr SMK Bullet
19.5gr IMR 4064 Powder

The goal is a (barely) subsonic load that will function with or without suppression.

Any suggestions for tweaks are greatly appreciated.

I would very much like to use IMR 4064, if possible.
9/18/2012 3:27:16 AM EDT
[#1]
Quoted:
Would anyone care to make a muzzle velocity prediction based on the following starting formula?

10.3" Barrel AR-15 with Pistol length gas
CCI Small Rifle Primer
220gr SMK Bullet
19.5gr IMR 4064 Powder

The goal is a (barely) subsonic load that will function with or without suppression.

Any suggestions for tweaks are greatly appreciated.

I would very much like to use IMR 4064, if possible.


You need a faster burning powder. What you are doing is stupid if not dangerous. Try anything from 4227,1680, Lilgun, h110, etc.

All the subsonic loads I have loaded were between 9-11 grains of powder.
9/18/2012 4:17:59 AM EDT
[#2]
Hodgdon doesn't even list that as a powder for 300 BLK, and they list pretty much every powder and cartridge combination that is useable, even if it doesn't offer optimum performance.  



Where did you come up with that load from?
9/18/2012 4:23:55 AM EDT
[#3]
Load data for 300 whisper will work  but the place to get advice is 300blktalk.com. They are the   people who have been playing around with all the  different combinations.
9/18/2012 4:38:17 AM EDT
[#4]
Quoted:
Hodgdon doesn't even list that as a powder for 300 BLK, and they list pretty much every powder and cartridge combination that is useable, even if it doesn't offer optimum performance.  

Where did you come up with that load from?


Its a 308/223 powder he likely has sitting on the shelf. Its very similar to Varget, but even harder to meter.
9/18/2012 5:58:52 AM EDT
[#5]
Quoted:
Quoted:
Hodgdon doesn't even list that as a powder for 300 BLK, and they list pretty much every powder and cartridge combination that is useable, even if it doesn't offer optimum performance.  

Where did you come up with that load from?


Its a 308/223 powder he likely has sitting on the shelf. Its very similar to Varget, but even harder to meter.


This.

I don't have to use it but I have a good bit of it on hand.
9/18/2012 6:04:24 AM EDT
[#6]
I figured it was a powder you had, but how did you come to that amount?  Did you just fill up a case and see how much it held, or did you pull the data from somewhere.
9/18/2012 6:43:41 AM EDT
[#7]
Can you even fit 19.5g of 4064 in a 300blk case with a 220grn bullet?

Middle range burn rate rifle powder in a low pressure sub-sonic load sounds like a recipe for a stuck bullet and eventual Kaboom to me.

9/18/2012 9:19:01 AM EDT
[#8]
10 to 10.8 gr of 1680, start high and work down. Thank me later.
9/18/2012 12:09:16 PM EDT
[#9]
Quoted:
10 to 10.8 gr of 1680, start high and work down. Thank me later.


Noted. Thank you.
9/20/2012 1:17:37 AM EDT
[#10]
Quoted:
10 to 10.8 gr of 1680, start high and work down. Thank me later.


This ^^^^^

Do not even think about trying to stuff 19gr into the case with that heavy of a bullet. I may not be a fortune teller but with that load I see a Kaboom in your future.
9/20/2012 1:48:00 PM EDT
[#11]
I tried 3031 and 4064 extensively in my 300 BLK and they both sucked.  They worked for supersonics but only marginally.  In addition you will NEVER get 19.5 grains of 4064 beneath a 220 SMK and if you somehow managed to cram it in your bullet would certainly be supersonic.

For a pistol length gas system AA 1680 is impossible to beat for subs.  It is my go to powder with 208 A-Max's, very accurate and very quiet through my 7.62 SD, also very consistent brass ejection.

Good luck, half the fun of this round is in working up loads.



9/20/2012 7:44:42 PM EDT
[#12]



Quoted:


I tried 3031 and 4064 extensively in my 300 BLK and they both sucked.  They worked for supersonics but only marginally.  In addition you will NEVER get 19.5 grains of 4064 beneath a 220 SMK and if you somehow managed to cram it in your bullet would certainly be supersonic.



For a pistol length gas system AA 1680 is impossible to beat for subs.  It is my go to powder with 208 A-Max's, very accurate and very quiet through my 7.62 SD, also very consistent brass ejection.



Good luck, half the fun of this round is in working up loads.


How true.

 



For me the most fun. Searching for, and going through many sources of loading data.




Figuring out what you want your load to do, picking bullets and powder to try and coming up with powder charges for test loads.






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