AR build advice

[mills0713]

I'm in the process of building my first AR. I have a LMT Specwar upper with 12.5 barrel, mid gas. After reading the "The Gun Every American Should Own" thread, I feel like a made a good choice. The lower will be a stripped LMT Mars-L (I shoot lefty and like the ambi controls). This will be a SBR (no brace). I also have a CGS Helios DT supressor that will live on this rifle. I will be shooting handloaded 77tmk or 73 eld-m.

Question: What buffer system should I use for this setup (buffer and spring)? Because I shoot lefthanded, I want to minimize gas as much as possible without sacrificing reliability. Again, I will not be shooting unsuppressed.

There is a lot of info on Reddit. I trust the folks here more. I'm completely new to this world, so treat me as such.

Thanks in advance.

 

[Formidilosus]

I'm in the process of building my first AR. I have a LMT Specwar upper with 12.5 barrel, mid gas. After reading the "The Gun Every American Should Own" thread, I feel like a made a good choice. The lower will be a stripped LMT Mars-L (I shoot lefty and like the ambi controls). This will be a SBR (no brace). I also have a CGS Helios DT supressor that will live on this rifle. I will be shooting handloaded 77tmk or 73 eld-m.

Question: What buffer system should I use for this setup (buffer and spring)? Because I shoot lefthanded, I want to minimize gas as much as possible without sacrificing reliability. Again, I will not be shooting unsuppressed.

There is a lot of info on Reddit. I trust the folks here more. I'm completely new to this world, so treat me as such.

Thanks in advance.

That is an excellent upper/lower, and an excellent suppressor.

H2 buffer and spring. You will be over gassed suppressed as that upper was specd around absolute reliability at -30° F unsuppressed. However it reliably functions at 120° F unsuppressed with very hot ammo as well. If you want less gas, the best answer is a Black River Tactical reduced gas tube.

 

[mills0713]

That is an excellent upper/lower, and an excellent suppressor.

Yeah, I'm excited to put it all together.

H2 buffer and spring.

I'm assuming this would fit the bill:

https://geissele.com/premium-mil-spec-buffer-tube-assembly-with-super-42-h2-black.html

I'm open to other suggestions if you think there are better options.

If you want less gas, the best answer is a Black River Tactical reduced gas tube.

If I were to go this route, would you recommend the same buffer spring combo you gave above? If not, what would choose to go with the BRT gas tube?

Also, which LMT BCG would you recommend?

I don't like screwing around with different setups. I want to find something that works and just go with it.

I really appreciate the advice.

 

[Burnt Reynolds]

https://geissele.com/rifle-parts/lower-parts/springs.html

Super 42.

I run in my sbr's (11.3 & 14.5) as well as both of my 16" guns and it's absolutely a fantastic piece of kit. Their guide will tell you what you need for the 12.5".

Suppressed guns as well as unsuppressed - everything lands in a nice little pile at 3 o'clock.

 

[Formidilosus]

Yeah, I'm excited to put it all together.



I'm assuming this would fit the bill:

https://geissele.com/premium-mil-spec-buffer-tube-assembly-with-super-42-h2-black.html

I'm open to other suggestions if you think there are better options.

That will work fine. So will milspec carbine spring and H2 buffer.

If I were to go this route, would you recommend the same buffer spring combo you gave above? If not, what would choose to go with the BRT gas tube?

Yes. The “standard” for AR with carbine stocks is a standard spring and H2 buffer- all of them should run without issue using that combo.

Also, which LMT BCG would you recommend?

Standard milspec

I don't like screwing around with different setups. I want to find something that works and just go with it.

I really appreciate the advice.

You’re on a good path. I would shoot it with the factory gas tube before changing anything.

 

[RockAndSage]

That will work fine. So will milspec carbine spring and H2 buffer.






Yes. The “standard” for AR with carbine stocks is a standard spring and H2 buffer- all of them should run without issue using that combo.





Standard milspec





You’re on a good path. I would shoot it with the factory gas tube before changing anything.

Given it'd be a suppressed SBR, any specific reason why you would not recommend LMT's Enhanced BCG? Especially if he doesn't swap out the gas tube with a BRT EZTune? It seems like it would be an optimal choice in that circumstance specifically.

 

[Formidilosus]

Given it'd be a suppressed SBR, any specific reason why you would not recommend LMT's Enhanced BCG? Especially if he doesn't swap out the gas tube with a BRT EZTune? It seems like it would be an optimal choice in that circumstance specifically.

The LMT Enhanced BCG is less optimum than a standard milspec BCG in the 12.5” Specwar guns. Initially they were used with the Enhanced BCG, but swapped pretty quick for standard carriers.
The Enhanced BCG’s really only come into their own around the design they were intended for- 14.5” carbine length way over-gassed barrels.

 

[mills0713]

That will work fine. So will milspec carbine spring and H2 buffer.






Yes. The “standard” for AR with carbine stocks is a standard spring and H2 buffer- all of them should run without issue using that combo.





Standard milspec





You’re on a good path. I would shoot it with the factory gas tube before changing anything.

Can’t thank you enough for the help. Going with H2, standard MillSpec spring, standard BCG.