Gas Piston for .300Blk

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

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MegaTon300
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Gas Piston for .300Blk

Post by MegaTon300 »

I am in the process of building an AR in 300 Blackout and I am very interested in using a gas piston system in it. However, I cannot find any kits that say specifically that they can handle the 300 Blackout. I've checked Osprey and Adams Arms and no luck. It seems to me that a kit that is designed for 5.56, 6.5 and 6.8 I would imagine that the 300 fits within there somewhere but you know what they say about assumptions :lol:
azarby
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Re: Gas Piston for .300Blk

Post by azarby »

MegaTon300 wrote:I am in the process of building an AR in 300 Blackout and I am very interested in using a gas piston system in it. However, I cannot find any kits that say specifically that they can handle the 300 Blackout. I've checked Osprey and Adams Arms and no luck. It seems to me that a kit that is designed for 5.56, 6.5 and 6.8 I would imagine that the 300 fits within there somewhere but you know what they say about assumptions :lol:

I'm wondering about the same thing. Adam Arms has a Pistol kit, but I'm reluctant to buy it until AA says they have tested it with the 300 BLK.
HotHolster
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Re: Gas Piston for .300Blk

Post by HotHolster »

My brother in law used an Adams piston kit on a Spikes upper. I'll have to check to see if it was a carbine or mid length. He took it to the range and said it worked flawless. The only problem was he bought some cheap Thermold mags and they wouldn't feed the 300Blk so he went back to the PMags.
renegade6
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Re: Gas Piston for .300Blk

Post by renegade6 »

For what it's worth, LWRC who is known for only making piston AR's will be offering a 300BLK that will be a DI gas system. Thought that was pretty revealing. I am certain they wanted to offer that baby with an operating system they have mastered. With how light of a powder charge these cartridges run I think it might be tough to maintain reliability with a gas piston system.
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Re: Gas Piston for .300Blk

Post by 300Blk »

I don't think that means that piston makes less sense for 300 BLK than 5.56mm - it really just means they did not have enough time to shorten the gas system on their piston upper. That being said, I don't understand people waiting for a piston system assuming it is better. It is like waiting for a turbo car rather than a normally aspirated car. There is no reason to assume one operating system is better - all that matters is the complete package / final result.
nolwark76
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Re: Gas Piston for .300Blk

Post by nolwark76 »

Robert, just trying to learn here. I was under the impression that the advantage of the piston system was that it's just a little cleaner. I have a PWS lower on a form 1 being processed by the ATF right now so I can buy a PWS 9" upper when it's approved. My reason was simply cleanliness and that I've never had a piston before. I realize with my can on there it will get some carbon back through the barrel into the chamber but much less than a DI.

What are the differences you've found in a DI vs. piston SBR? I have no doubt that the DI system is very reliable, that's not the reason I want a piston. Does it basically come down to Ford vs. Chevy because both are just as reliable, just one is more familiar and the other is slightly cleaner?
MegaTon300
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Re: Gas Piston for .300Blk

Post by MegaTon300 »

I emailed Adams Arms and Osprey defense last night and they both replied this morning.

Adams Arms:
Our system will work with the 300AAC however it will require some modifications on your end to your existing setup. I can’t tell you exactly what you need to do, but you will have to go through a series of tests & adjustments to get it to run. We have done limited testing and others in the field have had success.
Regards,

Osprey Defense:
We have not yet tested our system officially with that cartridge. I know some of our customers are using it, but I don’t know the tweaks if any they had to employ to get it to work.

Joseph Scimeca
General Manager

Still pretty vague but at least I got a fast response from each of them
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Re: Gas Piston for .300Blk

Post by 300Blk »

I am not aware of piston systems being cleaner on suppressed weapons.

DI is lighter, cheaper, and quieter.
regroovable
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Re: Gas Piston for .300Blk

Post by regroovable »

I built a 16" carbine length and swapped the Adams off my 5.56 to try it out.

It worked fine with my handloads on the full gas setting. When I ran subs through it, it worked and cycled fine (after a few loads - about 11 grains of 1680 worked on the 220's) but my barrel had a large gas port to begin with (about .125" with a quick micrometer check).

When I turned the gas system off and ran subs, it locked the piston system up (I'm guessing the carbon just hot-stuck the rod and sheath together) and I had to take it apart and separate them which was very difficult. This really sucks because it was scary quiet with the gas system turned off! Even with considerable lube, it still locked it up and even 10 rounds on full gas wouldn't break it apart and required manual cycling.

If you are shooting suppressed, it is just as dirty as the Direct Impingement due to the blowback. Regardless of the gas setup you choose, if running a suppressor - clean your chamber often!

I didn't notice a sound difference, but most meter tests show the piston to be louder.

I didn't feel that I was getting $300 worth of better performance out of the Adams on the 300 BLK, so I put it back on the 5.56 which is much hotter and I don't shoot it suppressed. The DI functions flawlessly and is a much cheaper setup for the BLK and it doesn't require an adjustable block to work both the subs or supersonic.
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Re: Gas Piston for .300Blk

Post by trenttyre »

Robinson Arms says their XCR Pistol and XCR Micro work with 300blk as well as other calibers for what its worth. I tend to really like the XCR and from what I understand they work well if you are willing to take the time to understand how it works and is put together.

Adams Arms said they were working on a 300blk setup before shot show 2011 but have been super quiet on what the hell is going on with the project now. Kind of drives me crazy.

Osprey's former manager sent me a PM on arfcom saying he got a pistol version of theirs to work with 300blk and was considering selling them as custom work. Ill check with him to see how its going.
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