I built a 10.5 AR, BA Hanson Barrel, Geissele SSA-E, Trijicon 1-4, but it just won't shoot groups.  3-4 in @ 100 yd.  Didn't like the 220 SMK.  Now working with the Hornady 208 ELDM, best at 12.1 CFE BLK.  Printed some 1.0 in. 50 yd groups, low SD at ~1025fps.  Seems to just fall apart at 100 yd , like vertical stringing.  Not sure where to go from here?  Have only used CFE BLK.

Do you have the same issue with commercial subs?

Haven't shot any.  Started with CFE BLK and Sierra 220's.  Worked a ladder, bad throughout.  Switched to the 208's worked a ladder and had some promise with 12.1 going about 1025 fps but it really opens up at 100 yd.  Interesting too b/c I'm getting a real low SD (7.0) but its showing vertical stringing.

I’ve tried W296. It gave me the best results. AA1680 was next. CFE BLK was last.

I haven’t found subs to be super accurate. A 45 isn’t particularly accurate at 100 either. They are also shooting a 200-230 grain bullet at subsonic velocities.

Okay good I have 296, I'll give it a try this weekend, thanks.

Yeah Rob, that is my expectation, 2" group or less.  Right now I'm not even getting what I call a group, its like a vertical string.  When I did my original load development I put my 4-16X on there but I hear you, that 4x is a challenge at 100.

I am using Barry's 220gr Spire point plated bullets for inexpensive plinking subsonic ammo and Maker Rex 220gr hunting ammo.  I am using IMR 4227 with the Barry's (noticeable quieter than H110/W296) and Accurate 1680 with the Maker Rex bullets.  Both will shoot about 2-2.5 MOA at 100 yards from my 9-inch pistol using a Vortex 3x Spitfire.  The would probably do a touch better with a better scope but for what I am using it for the 3X is really nice.  The Maker Rex bullets work exceptionally well at subsonic velocities.  I have had the bullets open before exiting a 12 ounce water bottle in testing.  Does a number on the up-armored Opossums.

Not sure I can find a box of factory right now unless I borrow one.  I've read about other guys doing well with the N110.  I'm going to try the WW296 since I have it to see if can can stay away from adding another powder to the collection.  Going to take the chrony out again and work the CFL BLK vs the 296 at 50 yd.  If that doesn't work then I'll try the N110.  Thanks for the help everyone.

OP,
    The old factory Hornady 208GR. AMAX subsonic load was easily sub 2 MOA in both the 16" RARR and 9" AAC carbine I use. Groups were usually in the 1.25"@100yd. range when using a Leupold 3-9X scope. Both rifles also shoot the Barnes 110GR. TAC-TX black tip & Lehigh 115GR. CCCu supers just as well. My normal sub load is a 150GR. FMJ over Unique @1000 FPS which is Hollywood quiet in the RARR with 762-SD can. But it will not cycle the AR action. Am at 128 varmints/predator/hog kills so far this year mostly with 150GR. FMJ subs. I only shoot whitetail with Barnes/Lehigh supers in 300BO and both work very well. Almost out of 150GR. FMJ so will change over to the 208GR. AMAX over Lil'Gun or H110 for my sub load which will also cycle the AR. AA1680 works for subs in ARs but is very gaseous which makes it LOUD. HTH

EDIT: Below are some of the 300BO subs & supers I have used. The Lehigh 194GR. ME was by far the most accurate expanding sub. The 150GR. FMJs over Unique @1000 FPS are extremely quiet, economical, and work great for headshots at night. The loudest noise heard is bullet impact.

Attached File

Very cool Leid, thanks for posting that pic.  Good to know you can get some bullets to expand at subsonic speed.  BTW, I revisited W 296 and was able to work up a fairly accurate load ( 5 rds just under an inch @50yd) with the 208 ELDM.  The other plus is that it was quieter and cleaner than the CFL BLK.

Try some IMR 4227. 10gr at 2.26 OAL with your 220 SMK. Everglades Ammo 220’s are pretty inexpensive and shoot just as well in my gun with 8.3 Hanson barrel.

I used Lil Gun with 220SMKs with no issues.  I am doing a bunch of 190SMKs now and they work well. All subs.  

I went to anneal some cases last night and my torch caught fire due to a bad seal.  I have no hairs on my right hand now.