300 blk won't cycle reloads

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jdubone1
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300 blk won't cycle reloads

Post by jdubone1 »

Just recently built a 6 inch 300 blackout pistol with adjustable gas block, and carbine buffer and spring, and have been able to run factory ammunition with no problems. Just can't seem to get it to cycle with my reloads using once fired brass, Hornady 150 fmjbt, Vihtyavuori n110 at around 12.0 grains at 2.100 oal. This load will cycle just fine in my 10.5 Noveske sbr build with the same gas block and buffer setup. Should I chance upping the load or what?
popper
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Re: 300 blk won't cycle reloads

Post by popper »

Barrel is too short. More gas needed.
Mike300
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Re: 300 blk won't cycle reloads

Post by Mike300 »

Will it cycle with gas block opened up all the way?
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GunFunZS
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Re: 300 blk won't cycle reloads

Post by GunFunZS »

you can increase the load up to the max range.

Or switch to a gassier / faster powder.

The fact that your gun cycled commercial loads proves it is possible.Nothing magic happens in factories that you can't replicate and probably exceed.
Blowout
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Re: 300 blk won't cycle reloads

Post by Blowout »

What factory ammo did you try?

According to the V V load data, 15.7gr is max with a 125gr bullet. https://www.vihtavuori.com/reloading-da ... rtridge=19
With a 150 gr bullet you might still have some room to move up. Where did you get your load data for N110 and does it provide any guidance to max load?

If you want to use the same load with both guns, you can try taking some weight out of the buffer, lighten the spring by taking off coils or try a AR15 carrier with the 6" build. I'd try those before drilling the port larger.
300Blk 8.0" pistol with 80% lower
STINKEY
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Re: 300 blk won't cycle reloads

Post by STINKEY »

Put the Can on or increase the powder drop.................................
If they say it can't be done.... I have or at least thought about it....... 8)
Naporter
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Re: 300 blk won't cycle reloads

Post by Naporter »

If your gas block isn't open all the way already I'd start there. There can be wildly different levels of port pressure in this cartridge based on a multitude of factors. The factory loads obviously provide more gas and thus can cycle. I'm going to guess you set your gas block using them? If so, open it up some. Also make sure the block isn't misaligned. If it is, it's restricting gas flow.

If it's already open and verified as properly installed, your load isn't producing enough gas pressure to cycle which leaves two options.

1). Upping port pressure by increasing your charge weight. I don't know how you worked up this load, but it's not a listed load on VV's website so proceed with caution if upping your charge.

2) Increasing gas port diameter to provide more gas volume. This is irreversible and should be a last resort.
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