Finding the right bullet

[tappedandtagged]

***See Post 18 for range testing of various factory loadings (with photos)***

I recently acquired a 14.5" SPR profile barrel from Ballistic Advantage and slapped her on my upper last weekend. The first few test rounds were a bit disappointing. For starters, my 55 grain Xtreme bullets FMJ hand loads were a 4" group at 100 yards. My 65 grain Sierra GK loads were about 2" at 100. Figuring these loads had been worked up for and optimized to my old barrel, I took the results with a grain of salt.

This past Monday I got to the range with a few factory Match loadings. The first I tried was Hornady Custom Match with their 75 grain BTHP. This resulted in a 3" group. I had another guy at the range try my rifle and he shot a 3-1/2" spread. He had been shooting sub 1/2 MOA with his 22-250 bolt gun before shooting mine, so I know it wasn't me. I tested this with my Specwar 556 on and off.

Right before I left, I shot 4 rounds of Federal GMM with the Sierra 69 grain MK. This shot right at 1.01" at 100 yards. I believe the 16 MPH gusts had a bit to do with this since the group was strung horizontally with only 1/4" vertical difference. Since I could only find one box of this ammo, I didn't reshoot without my suppressor. Also, I'm wanting to wait till the wind dies down.

Since those were the only 2 match offerings I could find locally, I went ahead and placed an online order with Midway. Next week I'll have the following to play with:

69 and 77 grain Federal Gold Medal Match (both Sierra bullets)
68 and 75 grain Hornady Custom Match
69 and 77 grain Nosler Match

Hopefully I'll be able to tell if my barrel likes the 68/69 grain pills or the 75/77 grain pills. Once I narrow that down, I'll probably buy a 100 round box of the bullet that seems the most consistently available and start load development.

Also, for those wanting specs on the rifle, they are as follows:
Windham Weaponry AR (the receiver and BCG anyway)
Vltor Emod stock
BCM Mod3 pistol grip
Geissele GS2 trigger
Geissele 13" MK 4 rail
SilencerCo Specwar 556
Burris 4-16X44 Signature Series scope
American Defense Recon-X mount
Samson Mfg BUIS
Ballistic Advantage 14.5" SPR barrel (from a contact overrun) with pinned ASR Trifecta mount
Edit to add per below question: 1/7 twist, 5.56 chamber, nitride finish