Heavier buffer and AGB

[oyster]

Hi Everyone,
I've only been in the AR game for about a year now. I bought an AR15 223 from my father in law that he won in a raffle, it was built by a local gunsmith so no pedigree. I swapped the upper for a 6.5G upper w/ 18" bbl and I use a suppressor. It seems like I'm getting more blow back with this set up. My thought is a heavier buffer and Surperlative AGB. Question is: what weight buffer H2, H3...?
Thanks
Jay

[Mad Charlie]

With the AGB, you might not need a heavy buffer.

[Sixoeight]

It's hard to tell if there even is an issue without shooting it ourselves, but a good AGB would be the only thing required to fix it if it is over gassed. I wouldn't touch the buffer unless you are just bored haha

[worthen86ford]

What length gas system

[biodsl]

With the AGB, you might not need a heavy buffer.

This might be the ticket if you want to use the lower on both the 5.56 and the Grendel.

[oyster]

This is the upper I purchased. Yes, I know it's entry level but so was my budget. https://www.ar15part.com/6-5-Grendel-Upp...fsg2rl.htm
It has a midlength gas system. The reason I believe it's over gassed is when you drop the mag out after shooting a round the top bullet in the stack is literally green and splotched like it had been in salt water for a week. When the .223 upper was on there it didn't do this. I also have a Radians charging handle that is supposed to help with blow back. Since I'm a lefty thats kinda helpful. Thanks for any info.

[A5BLASTER]

This is the upper I purchased. Yes, I know it's entry level but so was my budget. https://www.ar15part.com/6-5-Grendel-Upp...fsg2rl.htm
It has a midlength gas system. The reason I believe it's over gassed is when you drop the mag out after shooting a round the top bullet in the stack is literally green and splotched like it had been in salt water for a week. When the .223 upper was on there it didn't do this. I also have a Radians charging handle that is supposed to help with blow back. Since I'm a lefty thats kinda helpful. Thanks for any info.

You need to load one round in the mag and fire it and see if the bcg locks back.

If it doesn't then you know you have gas issues.

[LRRPF52]

18" MLGS in 5.56, 6.5 Grendel, .224 Valkyrie, etc. is going to be a tough nut to crack suppressed.

The reason is that you already have a lot of excess plug dwell with MLGS and an 18" barrel.

By adding a suppressor, it's like adding more barrel length because of accumulation in the baffle array.

I know guys who have broken bolts using both adjustable gas blocks and adjustable gas carriers at the same time when shooting suppressed.

These are the same problems Crane had when developing the SPR, so they went with RLGS 18" with a reflex Ops Inc can to really tame down the cyclic rate as best as possible.

I personally would not suppress a MLGS 18" unless it has a flow through can, and I would still consider adjustable gas carrier with extra power recoil spring and heavier buffer.

Of all of my personal 18" MLGS Grendels, I haven't even entertained putting my brake attach devices on them for use with my suppressor.

I am looking at the LaRue Tranquilo flow-through suppressor though for them, but would still prefer to cut the barrel to 13.7", P&W the brake, and mount that way just to keep overall length down.

[Klem]

The reason I believe it's over gassed is when you drop the mag out after shooting a round the top bullet in the stack is literally green and splotched like it had been in salt water for a week. When the .223 upper was on there it didn't do this. .

Oyster,

When you use a suppressor on an AR it is normal to have carbon forced back into the receiver and that includes the top of the mag. Removing the mag will see any unfired rounds at the top black and dirty. It also depends on the type of powder you are burning. If there is any excess cleaning/lube products I'm thinking that will also be splattered around and coat the brass.

52's analogy of the barrel being longer with a suppressor is a good one with the barrel remaining pressurized for longer until the round exits and the pressure drops. You will need to manage the overpressure in the gas/cycling system but that will not stop the carbon that's being forced back around the case and into the receiver and your face. By all means use an AGB, ABC, heavier springs and buffers to prevent the system from getting pounded to early destruction but the overpressured chamber will always be there with a suppressor. All the lefties I know (including myself) use shooting glasses to prevent suppressor spit in your eyes. The worst offender for left-handed spit is the HK MP5 K (9mm) with an attached suppressor. If you don't use glasses your eyes grit up to the point you have to retire to wash them. Unlike the MP5 SD this iteration of the MP5 was never designed to be suppressed. The AR's not so bad in comparison.









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[oyster]

Thanks for all the replies. Any recommendations on buffer weight, H2 or H3 can you get too heavy? Sorry for all the noob questions and every website gives a different answer. I'm using this gun for pig/deer depredation work so I want it to run as smooth as possible.
Thanks again

[Sixoeight]

I still think you would be served well with a AGB only. A certain amount of gas will send the bcg back to it's full travel without much extra energy. When you add a suppressor the gas pressure increases...so you just turn it down until it it correct again. The only problem I can see is if the AGB couldn't be adjusted low enough, but most if not all can be adjusted all the way to off, so that shouldn't be an issue.