Switchblock Gas port Diameters for 300 Whisper/Blackout ???

Discussion about rifles in 300 AAC BLACKOUT (7.62x35mm), hosted by the creator of the cartridge.

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DEF23
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Switchblock Gas port Diameters for 300 Whisper/Blackout ???

Post by DEF23 »

Hello all, I am new here but NOT to gun building or AR building.

I have a quick question about switch-block gas-port diameters for a dual purpose 300 Whisper/Blackout rig I am starting on next week.

I been doing my homework ahead of time and reading up on the subject matter in advance, so here goes:

Am I to understand that the sub-sonic 300 Whisper/Blackout factory uppers (16" barrel, carbine-length gas-system) like to be opened up to somewhere around .110" to .120" for positive function (I.D. of most factory measured gas tubes being .112 to .119").

However, the sonic 300 Whisper/Blackout of the same persuasion (16" carbine-length gas-system) can be ran as far down as .075" to .080" and still achieve reliable function, whereas they tend to beat the gun up a little more than necessary when using the larger gas port size, correct ???

So, is my thinking correct that a multiple-setting gas block would best function with the diameters/settings of .115" - .120" (100% or open), .075"-.080" (80% or partial) and fully closed (suppressor & "other" setting), in a 16" barreled, carbine length gas system, 300 Whisper/Blackout upper build ???

Thank You ahead of time for your answers.
DarkSoul
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Re: Switchblock Gas port Diameters for 300 Whisper/Blackout

Post by DarkSoul »

I have a Wilson Combat 16" barrel, and if I recall correctly, the gas port is .107 (but don't quote me on that), regardless, it's unmodified, and I shoot only supersonic rounds, all so far have been 147g slugs using 18 - 18.4g of A1680 . I have not had any issues at all with cycling, or hard cycling, actually, I have had a few, maybe 4 total failures to cycle (out of 300+ rounds, hence the reason of upping the powder charge). N adjustable gas block is probably a good idea if itsn the budget, I have a Blackfox Research "Cliq Block" on a 5.56 rifle, and it works fantastic for minimizing the unnecessary gas pressure in a carbine. I can use the standard mid length buffer assembly and still get perfect cycling.

If I were able to have SBRs and/or suppresors here in Cali, I would have run a Cliq block on the 300 as well just for the ease of tuning, someof the budget permits, it certainly couldn't hurt. Wilson claims that their barrels will work for both super and sub sonic ammo without any mods, so something to maybe consider barrel purchase wise, if they ever come back in stock.
-k-
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Re: Switchblock Gas port Diameters for 300 Whisper/Blackout

Post by -k- »

You can just buy a well designed barrel and shoot it. A big advantage of the 300 BLK over the 300W/30-221 is subsonic designed to cycle almost as well as normal ammo, so it doesn't run too hard with supers.

The difference in optimal gas port size between super and subs is not enough for us to make a Switchblock for the 300 BLK. I think you may have the gas port size for supers from a pistol gas system.
Todd
DEF23
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Re: Switchblock Gas port Diameters for 300 Whisper/Blackout

Post by DEF23 »

Thanks for responding to my question Todd.

IIRC, the over-sized gas port diameter was for people trying to get their sub-sonic loads to run with something other than 1680 (lil gun, 2400 and other stuff I believe).

It might be a match for the pistol sized gas port diameter, I wouldn't know, as I haven't been reading up on that configuration as I live in a NO suppressor state.

And while I like your companies design, I was actually thinking of the Paladin Machine gas block which is custom machined to the customers own specs.

I am using a Black Hole Weaponry 16" barrel with a carbine length gas system and I am basically trying to get the most across the board functioning out of it that I can, with the minimal modifications needed to make it run (Whisper & Blackout both in sub-sonic & sonic but without any buffer changes or anything).

As in immediate use --- a few mags of subs & then a few mags of sonics, without changing anything but the gas setting.

So, you are saying that it isn't even warranted. The stock barrel, with proper gas port diameter, on a carbine length gas system can shoot both type of ammo interchangeably without modifications, huh.
DEF23
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Re: Switchblock Gas port Diameters for 300 Whisper/Blackout

Post by DEF23 »

Do you have a link for where to get the cliq block, sir ???

I am in Kali, as well.
DarkSoul
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Re: Switchblock Gas port Diameters for 300 Whisper/Blackout

Post by DarkSoul »

You can get them here, http://www.blackfoxresearch.com/ , I don't know if they are in big production yet, so there may be a wait, but they work very well.
DEF23
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Re: Switchblock Gas port Diameters for 300 Whisper/Blackout

Post by DEF23 »

Thanks for the link, Sir.

I am looking at using a Paladin multiple setting gas block for my 300 build.

They only cost @ $60, are all steel and have up to 3 different setting depending upon which design.

I am ordering up the lo-pro model, so it will fit underneath an extended free float rail.

And the barrel will be here next week. Everything else I already have on the bench.

That's why I was looking into the different gas port specs.

I'm pretty sure I have it figured out (in my head)..........

.....After all, I did "scratch build" my own blow-back AR-45 (.45acp upper) on a dedicated STEN mag CNC guns lower......(and it isn't an Oly or a Colt system) LOL !!!

Thanks for the help guys, I'll let you know if I have any issues during the building phase or during function testing.
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300Blk
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Re: Switchblock Gas port Diameters for 300 Whisper/Blackout

Post by 300Blk »

DEF23 wrote:And while I like your companies design, I was actually thinking of the Paladin Machine gas block which is custom machined to the customers own specs.
Only Noveske makes a Switchblock(R).
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300Blk
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Re: Switchblock Gas port Diameters for 300 Whisper/Blackout

Post by 300Blk »

DEF23 wrote:So, you are saying that it isn't even warranted. The stock barrel, with proper gas port diameter, on a carbine length gas system can shoot both type of ammo interchangeably without modifications, huh.
Yes, that is why not a single company (or maybe not a single company with more than one employee) offers 300 BLK with an adjustable gas system.
jlindholm70
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Re: Switchblock Gas port Diameters for 300 Whisper/Blackout

Post by jlindholm70 »

DarkSoul wrote:You can get them here, http://www.blackfoxresearch.com/ , I don't know if they are in big production yet, so there may be a wait, but they work very well.
I have one on my 308 AR, works very well. Nicely made, kinda spendy compared to a Palladin or JP.
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