77gn SMK, 80gn SMK, 77gn TMK or 75 ELD-M

[Catch-22]

I’m interested to hear from anyone with experience shooting .223 or .223AI with heavy bullets, mainly out to 600m - possibly 900m.

Bullets I’m most interested to hear about include;

Sierra 77gn SMK and 80gn SMK

Sierra 77gn TMK

Hornady 75gn ELD-M

My .223AI barrels will be 26”, 1-8” twist and be for training on paper, not comps. I believe the .223AI chamber will be cut with a freebore of around 0.069”...similar to the  Wylde. I’ll be using .223 Accurate Mags (AICS pattern) which should allow me to seat bullets far out enough for a 2.700” COAL, so plenty of boiler room to play with.

Any experiences? 

Thanks!

[Bangbangman]

I only have a lowly “AR” straight-pull in .223Rem, Wylde chamber, so loaded to “AR mag” length. It has 1:8 twist barrel and I’ve been impressed with 77gr SMK, TMK, Scenar and Nosler Custom Comp. 73gr ELD-M not so good. 75gr A-max etc off the cards as can’t be loaded deep enough to mag-feed in an AR.

 

23.8-24.2gr N140, Varget, RS52 all worked well, with velocity and accuracy increasing in that order. 77SMK and Nosler CC virtually identical drop/drift. 77TMK marginally better on both counts  and accuracy. Best groups of 5 are 0.2-0.3MOA (NB straight-pull!), typically/normally sub 0.5MOA. In my rifle, all three bullets shoot to same POI at 100m, so long as N140/Varget/RS52 are used in the charge range above. So easy!

 

The only downside is the diminutive “splash”  of missed shots when shooting steels.

 

Since you are unconstrained by mag length (to an extent, so wider bullet choice) and have an AI version and longer barrel, you should have greater flexibility to tune a better long-range load; 900m is possible, ask Laurie!

 

[MichalS]

It is possible to shoot 77gr SMK to 800m. My friend recently shocked the competition by shooting 1.0MOA group at 800m with factory GGG 77gr ammunition from a 24" AR15!!! But, and that is a big but, there was no wind. None.

I plan on doing a similar thing (shooting 223 to 900m) and chose 80gr SMK as it is the highest BC bullet my twist (1:8) will handle. If I were building the rifle from scratch, I would go 6.5 twist .223AI for 85-90 grainers. By then though You have to consider if 6br is not a better option....

Michał

[Mattnall]

I have found 77SMks no good at 1000yds and the 80SMKs I could only just keep supersonic (with 45mins of drop from a 200 zero - little left to play with on my scope especially if I needed to add any wind). I haven't tried them at 900 but the next longest distance I've shot them is 600 and then even the 77SMKs are great.

I switched to 80JLKs and the elevation adjustment came down to 38mins and the group size could comfortably keep a Fig11 if I was playing nice (this was in the days of the 1000yd snaps in the PR nationals, 4x Fig11s on the backer).

Haven't shot them at 1000 for a while now, prefer to use the 6.5 instead.

[Catch-22]

Thanks very much for all the photos, help and insight, really appreciate it. @Bangbangman @MichalS @Mattnall

Seems there are a few good options and flexibility with powders. I was planning to use N140 and RS52 as I have plenty of these powders for use in other cals.

 I think I’m likely to use the 77gn TMK and/or 80gn SMK as they’re readily available. 

I had thought about going with a 1-7 or 1-6.5” twist and throat it for the 90gn+ bullets but i felt the faster twist will have a negative impact on barrel life and really I’d need to single load those long bullets when they’re seated optimally, which I don’t want to do. And I too agree with your point about better cals out there suited for 800m+, and plan to continue shooting my 6.5x47 at these distances, with the big .338NM for further out. 600m is likely to be the mainstay for the .223ai.

Thanks again all!