Carte blanche shorty build

I'm building a 11.5-12.5" pistol+brace (to be SBR'd at a later date). I can get pretty much any parts for it that I want, but the cheaper I make it the more cash I get on top of it.
I have a week or 2 to put together this parts list until my buddy gets the back pay from Uncle Sam to fund it, so a small backorder time on a part isn't an issue. I'm looking for suggestions on parts... which to choose and where to find... and I really just need a sounding board for my thoughts.
Prefer 12" even, but a half inch in either direction is acceptable. I know I want a KX3/KX5, a BCM medium charging handle, and obviously the Sig brace. I definitely want a free float keymod handguard, and I want it to be longer than the barrel but not more than 1", preferably less, but that means it has to have an inner diameter large enough to accommodate the KX3/most suppressors. I'd also like the rail to have keymod holes on all 7 sides like BCM's, not just 3, but that's not as important as proper length. I'd strongly prefer a hammer forged barrel, although I can't find any in stock other than an 11.5" on BCM. Blem/demo uppers and lowers are preferable but nobody seems to have any in stock. I really like that HSP light with the slanted back, and I'd like a hand stop that takes up as little space in front as possible (i.e. not Noveske's). I'm also going back and forth between a T1 micro and a dual-illuminated RMR, both have their qualities.

So I've narrowed it down to 3 barrels...

-Daniel Defense 12.5", chromolly steel, CHF, 1:7 twist rate, and includes a lo-pro gas block.
-Noveske 12.5" LGPRLP, unknown barrel material, CHF, 1:7 twist rate, includes lo-pro gas block and gas tube.

-Ranier Arms 12.5", stainless, button rifling (Ratchet Rifling on a Shilen blank), 1:8 twist rate.

All are carbine length. I like what I hear about 1:8, but I've never had a problem with 1:7. I like chromolly over stainless from what I know about it from rock crawling. I'm under the impression that CHF is superior to button cut rifling, but everyone says Shilen is top notch and their ratchet rifling seems like a good idea in theory. They're all within $20 of each other, but having a gas block included is certainly a plus. Thoughts?

http://palmettostatearmory.com/index...ile-upper.html

PSA 12.5" CHF with bolt group $399

Quote:

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Originally Posted by mcantar18c

So I've narrowed it down to 3 barrels...

-Daniel Defense 12.5", chromolly steel, CHF, 1:7 twist rate, and includes a lo-pro gas block.
-Noveske 12.5" LGPRLP, unknown barrel material, CHF, 1:7 twist rate, includes lo-pro gas block and gas tube.

-Ranier Arms 12.5", stainless, button rifling (Ratchet Rifling on a Shilen blank), 1:8 twist rate.

All are carbine length. I like what I hear about 1:8, but I've never had a problem with 1:7. I like chromolly over stainless from what I know about it from rock crawling. I'm under the impression that CHF is superior to button cut rifling, but everyone says Shilen is top notch and their ratchet rifling seems like a good idea in theory. They're all within $20 of each other, but having a gas block included is certainly a plus. Thoughts?

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What kind of ammo do you plan om shooting, factory or reloads?
Depending on band for the buck i like the 1:8 Rainer unit.
We run 12.5's on our sbr's. The spouse has a LH stag DI 1:9 chrome lined with a BPtactical bbl cut & thread. Myself, i've had so many bbls on the shelf i know it's a 1:9 chrome lined running an AA piston.

I'll be shooting mostly factory loads for the time being... whatever's cheap and available, really, and that includes the occasional box of steel case. Later on when I get a can I'll be shooting subsonic, and I'd really like to get into reloading at some point.
I'm looking for durability, long service life, etc. over best bang for my buck. If I have to drop some extra cash to get a barrel that will last 30% longer than the competition under the same conditions, that's what I'm going to do.
With that in mind... on one hand I know chromolly is incredibly strong when it comes to axle shafts and other rock crawling parts, so it makes sense that it would do well as a barrel material. On the other hand, Shilen's "ratchet rifling" claims to have an extremely long life (and their reasoning passes the logic test).

PSA 10.5" complete upper with BCG and charging handle $390...
https://www.ar-15.co/showthread.php?t=136443

Yeah I saw that. From everything I've read, the drop from 11.5" to 10.5" brings a significant loss in velocity and energy, and a significant increase in baffle erosion.

Quote:

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Originally Posted by mcantar18c

Yeah I saw that. From everything I've read, the drop from 11.5" to 10.5" brings a significant loss in velocity and energy, and a significant increase in baffle erosion.

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How far do you intent to engage targets at ? The 10.5 i had could do steel to 300. A drop of say 300fps isn't going to make much difference in the 25-300yd, on soft targets.

Issues with baffle erosion occur if you use a f/hider instead of a brake. On the 12.5 suppressed i run an AAC brake out.

https://sp.yimg.com/ib/th?id=HN.6080...8&pid=15.1&P=0 https://sp2.yimg.com/ib/th?id=HN.607...0&pid=15.1&P=0here's another one https://sp2.yimg.com/ib/th?id=HN.607...8&pid=15.1&P=0

While the 18" MVP wears a f/hider

https://sp2.yimg.com/ib/th?id=HN.608...6&pid=15.1&P=0

I'd like absolute certainty of bullet fragmentation in soft targets at 300. A buddy of mine with a 10.5" claims he keyholes at 300 with M855... are you saying this is an exception, not an example to go by?
I just discovered Simplistic Shooting Solutions' brake shield... fits around an AAC Brakeout and accomplishes the same goal as a KX3/5 when unsuppressed

I'm gonna run whatever's cheap. If I find a sale on 62gr that's what I'm buying... If 75 is the only thing in stock I'll grab that too. Most likely 55gr is what I'll feed it most, because of cost.