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2/16/2026 1:35:44 AM EDT
I want to build two uppers, one would like to do as a second Grendel.  The other is a 556 SPR/varmint.

I have two 556 barrels, one a 20" Rainier Ultramatch Mod 2 syainless fluted blem barrel. The other is an FN 16" CHF/CL fluted mid-length barrel. Plans are for 77 SMK or 77 TMK hopefully for use with either barrel and haven't decided on what suppressor.

The optic will be a Vortex viper PST Gen 2 3-15.

Mainly for range and coyotes. Liking the 16 for weight and ease of movement,  any suggestions?
2/16/2026 6:38:36 AM EDT
[#1]
For a coyote and dedicated "precision" rig I'd opt for the 20". No need to chase velocity numbers. Most all 75-77 grain pills will be 2700 or north of.

Now, if you are gonna go all out and go suppressed, I'd probably opt for the 16.
3/9/2026 9:55:56 PM EDT
[Last Edit: LeadBreakfast][Edited] [#2]
Suppressed, 16" without a doubt. My thermal setup is a suppressed 16" shooting 77gr TMKs, perfect coyote rifle. I did a 20" previously and it's just too long for inand out of vehicles constantly.
Malcolm X was right about liberals.
4/21/2026 8:33:26 AM EDT
[Last Edit: DevL][Edited] [#3]
Cut the 20" to 18" and use it. Accuracy difference will be night and day between the two barrels. I bet that 16" is going to severely disappoint you in the accuracy department.

Are you choosing the optic to buy or is it something you already own?
4/28/2026 9:15:30 AM EDT
[#4]
Already own the optic. Got it bore sighted at 50 yards and was looking with cheap ammo, unfortunately I have not had a chance to do more with it.  Had new suppressors come in and some more new guns.  Too much, not enough time.
Dare to tame me. Nothing can hold back my rage. Dare to tame me. You can't fool the faithless. Dare to tame me. Fear the man who lost it all.
5/14/2026 10:35:24 PM EDT
[#5]
I have a Rainier Ultramatch Mod 2 in the 18” SPR profile and wow, it’s a damn shooter. It’ll hold MOA or better and zero shift with a can is maybe an inch. FGMM 69 grain and IWI Razorcore 77 grain are the most accurate loads I’ve shot.

I’m not sure who Rainier gets them, I doubt they’re making them in-house.
You see that head come apart?
6/5/2026 10:02:08 AM EDT
[#6]
I have a couple Green Mountain barrels, a 16" and 13.9" both medium weight and medium gas chrome lined. From the few rounds I have put through them while sighting in, they show great promise in being tack drivers with my reloads. Need more time on them at distance and now that I have a range to use again, hope to find time to test further.
6/5/2026 2:00:44 PM EDT
[#7]
Quote History
Originally Posted By Ronnoc:
Already own the optic. Got it bore sighted at 50 yards and was looking with cheap ammo, unfortunately I have not had a chance to do more with it.  Had new suppressors come in and some more new guns.  Too much, not enough time.
View Quote


"Cheap ammo" and accuracy rarely coincide.

It makes zero sense to me to buy a premium barrel and feed it junk ammo, i.e. M193/M855. 1:7 and 1:8 twist barrels will shoot most varmint bullets very well. Hornady SP SX will probably blow up before hitting your intended target because of high RPM G-Forces. Speer 50 grain TNT's may or may not work, depending on how fast you run them and the interior finish of your barrel.

My best groups have been fired from fast twist barrels using 52/53 grain match bullets. Sierra Blitz Kings have been very accurate, and they don't come apart in flight.

I would suggest White Oak Armament's;

1. WOA 3-Gun barrel 2.5-pound version. It's their heaviest 3-gun barrel but is actually a mid-weight by most standards.

2. WOA SPR barrels, which come in 16", 18" and 20" variants, 1:7 or 1:8 twist.

3. WOA Predator barrel, the heaviest barrel I would consider. You can choose 1:12 twist as a dedicated varmint rig, or 1:8 for an all-purpose rifle. They come in 18" and 20" options. I suggest the 1:8, so you can shoot everything up to 80 grain bullets.

6/5/2026 2:56:27 PM EDT
[#8]
I have a Black Hole barrel that has been good.
6/5/2026 5:46:36 PM EDT
[#9]
I also have that WOA 3-gun 18" midweight with their intermediate gas length. It also shot really well with all the different  bullet weights I have in the armory. Did not seem bullet picky at all.

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