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Thread: 300 BLK AR15 DDM4V7 Upper
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08-03-2015, 21:19 #1
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300 BLK AR15 DDM4V7 Upper
Need some help reloading subsonic ammo 220gr point CCI400 Small rifle primer for 300 Blackout 16" barrel Semi Daniel Defense DDM4V7.
I have bought powders MP200, S221, S265, S321, S335 and S341 to test.
Powders MP200, S221, S265 can speed up the 220gr point to easily 1030 fps but does not create sufficient gas to cycle (reload)the action.
Powders S321, S335, S341 cycle the action but not enough speed, powder reaches case capacity.
If I mix powders MP200 and S335, 3.3gr and 8gr I get the action to cycle occasionally. (Reaches case capacity)
If I mix powders MP221 and S431, 4gr and 7.5gr I get the action to cycle occasionally. (Reaches case capacity)
Using factory ammunition Remington 300 AAC BLACOUT 220gr OTM R300AAC8 it cycles every time, I have stripped a round and found 10.5 gr propellant inside. Using this loud in one of my casings with CCI400 primer and 220gr Nosler HPBT point it cycles the action no problem.
I have tested different buffer spring and H3 buffer weight.
Somchem powders does not produce sufficient gas to cycle action.
I have posted a email to Somchem for guidance.
Any advice?
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08-03-2015, 22:00 #2
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Re: 300 BLK AR15 DDM4V7 Upper
Maybe something here. http://www.gunsite.co.za/forums/show...-Journey/page2
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27-04-2018, 06:19 #3
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Re: 300 BLK AR15 DDM4V7 Upper
Can any of the mnore experienced reloaders comment on the OP's mention of mixing propellant powders to achieve a desired result with his rifle.
I am still relatively new to reloading, and have never heard of people doing this, but my common sense tells me that this one of those "don't try this at home" ideas, in other words, you could literally be playing with fire.
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27-04-2018, 06:37 #4
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Re: 300 BLK AR15 DDM4V7 Upper
During the 80's it was common amongst some of the pistol shooters in SA to mix different gun powders to obtain certain characteristics. An older shooter explained it in a thread maybe three years ago.
In rifles it is known as duplex loads. X grains of powder A on top of Y grains of powder B gives a hotter flame later in the burning process at a lower pressure. If memory serves correct the initial charge is slower burning powder which ignites the charge of faster burning powder.
In handguns it can apparently be done but in rifles it is generally considered a part of dark science aka alchemy and asking for trouble. I know of one person in Namibia who has ample experience in this.
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27-04-2018, 06:39 #5
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27-04-2018, 09:08 #6
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Re: 300 BLK AR15 DDM4V7 Upper
I'm just going to throw this out there, but I'm unfortunately NOT speaking from experience - would an adjustable gas block not be required for this kind of situation? I know, you said that factory Remington loads do cycle properly, so I can understand the desire to try and match them, but I personally wouldn't be mixing powders, due to my own inexperience with such, and having read that it's a bad idea unless you REALLY know what you're doing (I can't comment on the OP's experience, so no judgement).
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27-04-2018, 11:25 #7
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Re: 300 BLK AR15 DDM4V7 Upper
Well the 300blk is designed be able to be shot suppressed with subs and supersonic without making any changes, and being a DD from my reading it should be pretty spot on although the 16" barrel isn't ideal for shooting subs it's not a deal breaker.
The main drawback is our locally produced propellants, which of the lot the best bet is the S265, but as you have found it's touch and go at best with subs... Supers though it's great.
Maybe try some of the imported propellants? I know there has been some talk of one of the Vihtavuori that looks like it would work, but the exact type slips my mind now. I also know there are Hodgdon Propellants which would work, and there was talk that DSG would be bringing in some Lil Gun, and CFEBLK in the next batch... whenever that is.
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