Interesting problem - pistol length gas block on midlength rail?

[gat0r]

if anyone is sticking w/ DI system, a new option is about to be released

http://www.ar15.com/forums/t_1_5/1277745_PALMETTO_STATE_ARMORY__MAJOR_SHOT_SHOW_2012_ANNOUNCEMENT.html

adj gas @ upper location
looks interesting

[CJ]

There *seems* to be some difficulty getting the AA Piston kits to work on .300 BLK guns, but it's all hearsay, I haven't read anything confirmed.

[KBScobravert]

There *seems* to be some difficulty getting the AA Piston kits to work on .300 BLK guns, but it's all hearsay, I haven't read anything confirmed.

Have you asked Adams Arms of they are working a .300blk kit?

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[CJ]

Have you asked Adams Arms of they are working a .300blk kit?

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Yep, they said no they are not, and no they don't plan on it.

[ThreeFingerPete]

I wonder if it has to do with the lower volume of gas forced into the port and the additional mass of the piston.

[bottlerocket]

if anyone is sticking w/ DI system, a new option is about to be released

http://www.ar15.com/forums/t_1_5/1277745_PALMETTO_STATE_ARMORY__MAJOR_SHOT_SHOW_2012_ANNOUNCEMENT.html

adj gas @ upper location
looks interesting

Looks promising! I might have to pick one of those up for my build.

And CJ, thats a badass rail setup. Looks damn near custom built to solve your problem. How does the handguard attach together? In the 4th pic it looks like its being held together by a rail segment, but in the 3rd it looks seamless. Different setups or do they actually attach in a different way?

[CJ]

I wonder if it has to do with the lower volume of gas forced into the port and the additional mass of the piston.

It's a higher volume of gas, but less pressure. The pressure curve is different, so you have to mess with it more apparently.

[CJ]

Looks promising! I might have to pick one of those up for my build.

And CJ, thats a badass rail setup. Looks damn near custom built to solve your problem. How does the handguard attach together? In the 4th pic it looks like its being held together by a rail segment, but in the 3rd it looks seamless. Different setups or do they actually attach in a different way?

the side rails do it, I think the second picture is just an extended rail it's less visible.

[ThreeFingerPete]

It's a higher volume of gas, but less pressure. The pressure curve is different, so you have to mess with it more apparently.

Higher volume, but how is it affected by the larger bore? I guess I could just go read about it.

[CJ]

Higher volume, but how is it affected by the larger bore? I guess I could just go read about it.

Yeah it has a substantially higher volume in the barrel, which causes a lower pressure. To counter it they switched to a standard pistol length gas system. The problem is because you have such a small barrel distance to the gas block, it's substantially more effected by small pressure changes in the cartridge. I think it's best described as .223 has a high pressure "click" when it cycles the piston, and a .300 is more of a thump (with it's lower pressure) which can cause issues, so buffer springs etc. play a bigger part.

The truth is, I've only found 1 or maybe 2 guys that have done a piston setup on a .300 BLK, so right now you just need to figure it out yourself.

[KBScobravert]

Well, good news I suppose! I called Samson MFG because I honestly didn't understand wtf their evo rail did exactly. Their website is fairly confusing.

I spoke to Andrew up there and he was great. Apparently, all of their evo series rails have a gap for a piston setup. Then, you can extend the rail another 4" on front of that. Pretty damn cool!










Which means I could buy their pistol gas block rail, which is 4" of top rail, and 3" of side rail. Then add the 4" extension, and I have a complete rail with access to my piston block which measures 11" total. Meaning 2" of my suppressor will be inside the rail (and it's 1.65" ID so it will fit!), and 7" will be exposed. So that's awesome. The best part is their rails are pretty cheap ($165 for the rail I'm looking at). And their huge ID is awesome.

I just ordered this setup. Should be here in a few days for a fit test. I will be testing it on a .300blk 9" that CJ point me to an adapter to mount my Gemtech 9mm suppressor.

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[CJ]

I just ordered this setup. Should be here in a few days for a fit test. I will be testing it on a .300blk 9" that CJ point me to an adapter to mount my Gemtech 9mm suppressor.

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Must be nice, I do all the hard work and you just swoop in and steal it, just like that.

[KBScobravert]

Must be nice, I do all the hard work and you just swoop in and steal it, just like that.

Speaking of hard work, get back on the presses. I should be up and running this weekend.

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[CJ]

Speaking of hard work, get back on the presses. I should be up and running this weekend.

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I need to buy some powder. Need to do some research tonight.

[CJ]

I need to buy some powder. Need to do some research tonight.

Okay, I need to buy AA1680 for subsonic, and H110 for supersonic. Broke at the moment with various jeep projects.