.224 77gr Sierra TMK didn't make it to the target

[Ironworker]

Shooting my 22 Creedmoor today in the hot NV desert. I was experiencing terrible, mysterious groups (Oblong holes) and missing shots at 100 yards, but only with Sierra 77gr TMK bullets. Hornady 62-grain ELD-VT bullets shot well. The 85.5gr Bergers did okay. I fireformed some 53gr V-max (22/250) they did fair, but made it to kick up dirt at 300yds.
I never had this problem in the wintertime with these bullets? 8"twist 3,425 FPS. I just bored-scoped the BBL; it needs cleaning, but the Carbon ring was minimal. I was worried that my BBL was shot.

 

[CJ6]

Pull a couple (if you have any left) and double check your charge weights.

 

[jelenko]

Not sure that's the right direction.
With the 77's at 3400 fps and keyholing but the 85.5's not, it's not clear what's going on.

I can say that the 77's are spinning a bit fast at over 306K rpms. That could cause them to go poof in less than 100 yards, but not keyhole.

 

[Ironworker]

Not sure that's the right direction.
With the 77's at 3400 fps and keyholing but the 85.5's not, it's not clear what's going on.

I can say that the 77's are spinning a bit fast at over 306K rpms. That could cause them to go poof in less than 100 yards, but not keyhole.

I looked at a schematic of both a Sierra Tipped Match king and a Tipped Game king. The TMK has a thinner jacket.

 

[boltfluter]

A hot barrel, high rpm, and a match jacket. Some bullets will survive and some will go "poof". Try them again with a clean barrel and shoot at first light (cooler temps) and they will probably be fine. Good luck and keep us posted.
Paul

 

[vonb]

What boltfluter said. I had a Savage years ago in .223 with a 9 twist barrel. On a hot day and with a hot barrel, I would see Hornady 75 gr HPBTs go poof about 10-20 yards in front of my muzzle. I'd never had that issue before that day and the barrel wasn't shot out.

The combination of a rough barrel (e.g. Savage) and shooting with a hot, dirty barrel stressed the jackets. Clean it and shoot with a cool barrel and the barrel will most likely go away.

 

[r bose]

Shooting my 22 Creedmoor today in the hot NV desert. I was experiencing terrible, mysterious groups (Oblong holes) and missing shots at 100 yards, but only with Sierra 77gr TMK bullets. Hornady 62-grain ELD-VT bullets shot well. The 85.5gr Bergers did okay. I fireformed some 53gr V-max (22/250) they did fair, but made it to kick up dirt at 300yds.
I never had this problem in the wintertime with these bullets? 8"twist 3,425 FPS. I just bored-scoped the BBL; it needs cleaning, but the Carbon ring was minimal. I was worried that my BBL was shot.

How many rounds on the barrel? At those speeds 22 Creedmoor isn't going to last long

 

[Ironworker]

How many rounds on the barrel? At those speeds 22 Creedmoor isn't going to last long

500-600 rounds.

 

[r bose]

500-600 rounds.

That shouldn't be close to shot out. 500-600 times 3 and I'd be worried. I'd clean it very well, perhaps JB the throat area to smooth out any firecracking then retry. It's the tumbling of bullets, getting oblong holes thru the target that is puzzling.

 

[SKWERLZ]

Shooting my 22 Creedmoor today in the hot NV desert. I was experiencing terrible, mysterious groups (Oblong holes) and missing shots at 100 yards, but only with Sierra 77gr TMK bullets. Hornady 62-grain ELD-VT bullets shot well. The 85.5gr Bergers did okay. I fireformed some 53gr V-max (22/250) they did fair, but made it to kick up dirt at 300yds.
I never had this problem in the wintertime with these bullets? 8"twist 3,425 FPS. I just bored-scoped the BBL; it needs cleaning, but the Carbon ring was minimal. I was worried that my BBL was shot.

Sounds like you found the limits of the 77.
You do know that that poor bullet is spinning 310,000 rpm right?

It can definitely get worse as barrels get hot or worn.

Interestingly at 280k rpm the Berger 300 gets squirrelly and sometimes Houdini’s as does the 7mm 180ELD

At those speeds a 8.5 or 9 twist might be a better option.

 

[Ironworker]

I was shooting 69gr HPBT bullets today behind Re#17, and the rifle shot 1,2 MOA. So I guess my bbl still has some life left.