A lighter buffer?
Trigger hammer considerations?
A different buffer spring?
(I was after a BCM BCG and they only come in Auto configurations.)
Ok, I guess I should add that it will be for a 14.5 barrel with midlength gas.
Edit: unobtanium hereby obtained! lol
None. F/A carrier works universally with a notched or Type 1 hammer.
Weight differences are negligible. Should be no need for a buffer change.
USGI spring… amazingly… :eek: Works fine. 
Ok, I guess I should add that it will be for a 14.5 barrel with midlength gas.
op updated
None.
Ok, the plan was to use an H buffer so I’ll stick with that.
If I DO need to use a different buffer or spring I’m charging both of you fye dollah 
Depending on the port size, you’ll want and H1 or H2 carbine buffer. But the BCG won’t impact that part of the equation.
For a BCM, an H1 will probably run optimally. Most other brands will use an H2.
None.
I’ve owned 3 Middies, 16" Saber Defense, LMT MRP and a DD 14.5" Middy LW. All function fine with a F/A BCG, H Buffer and the buffer springs they came with. FYI, all functioned just fine with a carbine buffer, especially with under powered eastern european steel cased ammo.
I’m running the same setup. 14.5" middy, F/A BCM bolt, and I use a regular carbine buffer and spring. Runs like a raped ape!
A FA carrier will work with just about everything except the discontinued Colt lowers with a sear block.
Standard carbine spring and buffer.
Specialized Armament does a beautiful job of milling off that fucker. They did Pappabear’s gun so he could run a real carrier.
o’ say it it aint so;)
all I use never had issues
The hipsters don’ seem to have problems with the metro springs either… 
how flat is it?
I have owned four 14.5" mid-lengths. All had FA BCG. All had H buffers. All ran perfectly.
op updated.
Build continues 
Not sure if you are using a BCM barrel, but I have a BCM 14.5" mid-length with BCM BCG, H-buffer and have no problems.
Yep, it’ll be a BCM BFH 14.5 middy
The ‘metro springys’ work better with our spray on satin shirts and homo keymods.
-Jax
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Removed
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yes an H buffer is marked with an h–H2 usually has H2 stamped in it.
H buffer weigh around 4.1-4.4 ounces-H2 Is4.4-4.9–they go in an order of weight-all are around .4ounces heavier. example–carbine buffer weight around 3.7 ounces-H buffer is around4.1-4.4.Not all companies follow this though, but most do. Example --spikes tactical has an st-t2–they are saying its H2 (T2) but it weighs between H2 and H3 buffers.There are other example, but mainly all stick to the regular .04 to .044. there are also pistol buffers–short and heavy to work in a 9mm carbine.weighs around 5.5 ounces(never use1 in you gun).Now–especially on a carbine lengthed rifle, the heavier the buffer,the slower the lock up time—which makes a gun more reliable and weigh less and also more efficient-.It also prevents bolt bounce and exessive wear on the gun . But you must be carefull not 2 get too heavy or the gun will short-stroke. you can also "tune a gun with heavier or lighter springs–its all complicated–and every gun is different