95gr SMK Question

[hdwrider]

I have a Bartline barrel with a 1 x 6.75 twist to shoot 95gr SMK pills. Does anybody have
any ideas as to a parent case to start with. I really don't want to form cases. I am looking
at 22 Creedmoor, but Creedmoor brass is hard to find.

 

[Evan]

22-250? May land you around 3200fps. Get too much case capacity or speed and you'll blow up bullets.

 

[Jdne5b]

Necking down 6/6.5 Creedmoor is out of the question?

22 Valkyrie or 22 Nosler? You'd possibly need custom/longer throats than standard though.

 

[10XSHOOTER]

Might try a 22 BR. But a 22 Dasher would work great

 

[paperpuncher]

How fast do you want to make them go?

 

[r bose]

Think the 22 Valkyrie was designed around the 90g bullets? Mag fed, right speed, super sonic past 1000

 

[McFred]

I'd consult barrel manufacturers' and Sierra's opinions before hotrodding the 95SMK. IME (4-groove 1:7 Krieger) much past 3000fps you'll start blowing them up depending on the land/groove configuration and throat condition.

Also if you want .22C'Moor performance you can look into .22-250 Ackley as well. They're virtually the same thing other than requiring fire forming.

 

[Ned Ludd]

I am thinking the same thing as McFred. With a 6.75-twist barrel, a .223 Rem or .223 Rem AI should work just fine, but if you go with something much faster, shedding jackets might be an issue unless you load them up slow.

 

[XTR]

I'm with these guys. I'm pretty sure that Sierra made that bullet with F-TR shooters as the target audience, so they are looking at 223 speeds. You start spinning a bullet out of a 6.75 at 3000+ and it's not going to hold up. At 3000FPS± you are running 320,000RPM out of a 6.75 twist; that's the same spin rate as running 4000FPS out of a 1:9.

 

[Evan]

Even the 90 class of bullets blow up. Seems like 77 and down are more tolerant if you want to push more speed. I've heard of the 75 eldm and 77 rdf going 3600 without too much drama.

 

[B23]

I'm with these guys. I'm pretty sure that Sierra made that bullet with F-TR shooters as the target audience, so they are looking at 223 speeds. You start spinning a bullet out of a 6.75 at 3000+ and it's not going to hold up. At 3000FPS± you are running 320,000RPM out of a 6.75 twist; that's the same spin rate as running 4000FPS out of a 1:9.

You are spot on. I talked to Sierra right when these first came out because I was thinking about doing a 22-284 build to specifically to shoot these and their concern was the massive RPM's a build like that would generate could very likely cause them to fly apart shortly after launch. The Sierra Tech told me they mostly had the fast twist 223 shooters in mind when they made these.

 

[284winner]

22-250? May land you around 3200fps. Get too much case capacity or speed and you'll blow up bullets.

More importantly, too fast of twist in those high capacity cases will blow up bullets. Those rpms are death to jackets.

 

[hdwrider]

Thank you for all the help. Ive decided to go with a .22-250, and start around 2900 fps.

 

[mysticplayer]

Just started shooting my 22 CM with 7 twist barrel and the Sierra 95gr MK. Got some very nice test groups at 200yds using H4831SC... ball park 2900fps. Will try and adjust but was looking around 1/4 MOA so really excited.