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.300 blk out questions please

tminc

Private
Full Member
Minuteman
Dec 4, 2007
62
0
texas
Im going to put together a .300 blkout this year for varmnit huntingI have the choice of 8,12.5 and 16 inch barrel. Im going to supress so my question is,how much difference does barrel length make in velocity with subsonic loads for this caliber?whats the best lower for a hunting weapon? thx for your time.
 
Re: .300 blk out questions please

If your just using it for varmnit hunting, I would go with a bolt gun with a 16" or 20" barrel. If your heart is set on a AR, any lower will do just fine for hunting. Its how ever you want it to look and how much you want it to weigh. Just my 2cents on it. Its a great round and much fun to shoot! Good luck with your build and have fun!
 
Re: .300 blk out questions please

Remington rates the 9 inch barrel at 965 fps and the 16 inch barrel at 1010 fps average for subsonic. You should probably just get 16 inch unless you just want compact.
 
Re: .300 blk out questions please

Currently running a .300 BLK on a Delta Co Arms build mega upper and lower. 16.5 bbl w 8 twist, and an AAC 7.62sd can. 100 yard group is well under moa and it is quiet.
My bolt gun is 16 in and shoots just as well.
Only running the factory Rem sub ammo for now. No issues with hitting supersonic. Hope this helps.
 
Re: .300 blk out questions please

300Blackout.com states that with AA1680 11.2 grains is the recommended charge when loading 220 SMK's for subsonic use and to reduce the load as needed. What is the safe minimum and maximum?

I'm using an 8" Noveske.

Sorry if this question has been asked already.
 
Re: .300 blk out questions please

Has anyone seen the blackout Remmy model 7's? The ones I seen had a lightweight barrel. I wonder if there is any out there with a heavier barrel?
 
Re: .300 blk out questions please

Any lower will do. There is approx. a 200fps difference between 9" and 16" I would choose a bolt gun over AR for varmint.
 
Re: .300 blk out questions please

With factory Remington ammo you have to be careful as Remington loads them to the very edge of subsonic speed with a 16" barrel. I have chronoed them before and it was averaging around 1090FPS. That is, if you want to stay super secret squirrel quiet. And the 220 factory subs are the last thing I would want to kill any varmints with. We have shot it plenty at animals and they just go right through with no expansion.
 
Re: .300 blk out questions please

Chronographs tend to show the speed of sound rather than velocity for subsonic rifle ammo if you don't use a blast shield or silencer. The Remington ammo is loaded to 1010 fps in their factory test barrel, but various individual barrels react in different ways.
 
Re: .300 blk out questions please

For an AR i would choose a 8" barrel. Its going to get you to the same distance as a 16", so if you want a SBR go 8, otherwise go 16. Anything in between is just extra length and weight. They are a blast to shoot and i know my 8" will be responsible for more kills than anything else i have this year
wink.gif


We have a bolt gun with a rock barrel and factory Remington 220gr SMK's are going too fast.

This one has a 10" barrel and is right at 6lbs without the suppressor. The 8" version the suppressor sticks out about half as much as you see in the pic

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Re: .300 blk out questions please

Personally I went with the AAC 9" barrel. The only reason I chose this over the 8" that Noveske offered was because of the fact that there is some doubt as to how reliably the Noveske can cycle sub-sonic ammo unsuppressed. There were plenty of claims on forums and what not but as long as the manufacturer's stance is that it's a question mark then I wasn't willing to bet on it. If something happens and I need to strip the suppressor off I need to be assured that it will still function 100% and wasn't willing to chance it. It's too bad because I would have loved saving another inch but in the end an inch wasn't worth it when I could buy a complete AAC upper that had the manufacturer's support regarding the subsonic ammo sans suppressor.
 
Re: .300 blk out questions please

We are using cut rifled rock barrels in our guns and they build pressure a bit differently than standard barrels. Our guns will also come with our adjustable gas block so the end user can make them cycle however they want.
From what i have found if you get a barrel to cycle subsonic's without a suppressor reliably they are very much over gassed if you run supersonic thru them. Its hard to find the perfect balance, but with a adjustable gas block you kind of get the best of both worlds.

 
Re: .300 blk out questions please

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: heatseekins</div><div class="ubbcode-body">We are using cut rifled rock barrels in our guns and they build pressure a bit differently than standard barrels. Our guns will also come with our adjustable gas block so the end user can make them cycle however they want. </div></div>

This would be a very hand feature but for some people it's cost prohibitive when you can buy an entire upper (DSA) for about the price of a switchblock. this would be the answer for those who want to run everything, super/sub/suppressed/unsuppressed with the same setup. For me, I've just decided to run the subs adn call it a day but I really would like the flexibility to run ALL options.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: heatseekins</div><div class="ubbcode-body">From what i have found if you get a barrel to cycle subsonic's without a suppressor reliably they are very much over gassed if you run supersonic thru them. Its hard to find the perfect balance, but with a adjustable gas block you kind of get the best of both worlds. </div></div>

Yeah, to run unsuppressed subs you would need the port opened enough that the pressure would be really high running supersonic suppressed. I get that it's difficult to find a balance and that's why I was warning the OP about the possible downsides to going with the 8" that you suggested. It seems like maybe that inch of extra length could be the solution which would make not all lengths between 8" and 16" not moot.
 
Re: .300 blk out questions please

I couldn't tell much of a difference when i got shorter than 12" and have herd of some running all the way down to 6" with good results. With short barrels you kind of need to pick your poison and set it up for specific task (like you have) or just adjustable.

Chris from HA above has allot of experience with blackouts and im sure can help set you up the best way and get you dialed in the first time.
 
Re: .300 blk out questions please

So, when you remove the AAC suppressor from under that handguard, you are just poking something through the slots in the handguard to hold down the latch?