22 cal---55vmax/60vmax rpm limits?

[rockhound78]

Just threaded/chambered an 8" twist Bartlein barrel this morning, in 22Br. Just got back from the range and sighted the thing in and tried to get sight settings on our steel gongs. The 55vmax and the 60vmax didn't make it to the 200M gongs. They made it to 100yd paper, except for one 55grvmax. Velocities for the 55vmax were slightly above 3700 and the 60's were just under 3600

53vmax was fine, at least at 150M, but ran out of ammo before I could get to 200yds.

Just wondering if I was exceeding some RPM threshold for the 55/60vmax bullets?

 

[Mike402]

The generally accepted limit for Vmax's is 290,000 rpm. You are spinning the 55s at 333,000 rpm at 3700 fps from an 8 twist. You are lucky they are making it to 100

 

[AckleymanII]

55 and 60g v max work best in a 12 twist.

55g Sierra btsp has a match grade jacket, 60g Sierra will survive the trip.

55 and 60g Nosler ballistic tips will survive the trip also.

I am running 223 AI, 22/250 AI. As the barrel gets worn with cracking and pitting, issues abound with the V max at high rpm.

 

[K22]

I've obtain excellent results (accuracy) with the 60 grain Vmax in my 223 Rem Tikkas which have an 8" twist but they're running about 2900 to 3000 f/s behind 24.0 grains of H4895.

The 55 Nosler BT's also are working well for me in these rifles (8") but I had to reduce the powder charge about a grain from what I normally use in my 12" twist 223 Rem's.

 

[Texas10]

Velocity (times) 720, divided by twist (8)= RPM
3700 X 720=2,664,000 /8= 333,000 RPM.

Not many jackets will take that kind of RPM. Barrel internal smoothness/lapping etc will have some effect on jacket failure.

 

[rockhound78]

Thanks for the info. Suspected such. Would have preferred a 1-9" twist as I have some 70gr to put thru it, but this barrel was on a rifle I had traded for. It was a 22-243AI when I got it.
Will pull out the Nosler BT 55's and 60gr Sierra TMK and try them.

All my other 22's either have a 12" or 14" twists, this is my first foray with an 8" twist tube.

Thanks again

 

[Mike402]

This may help your barrel/bullet choice:

RPM Limits by Bullet
Dogtown 260,000
Varmint nightmare 260,000
Speer TNT 240,000
Hornady VMAX 290,000
Hornady SXSP 240,000
Sierra Varminter 216,000
Sierra Blitzking 352,000

Of course there are probably cases where people have exceeded these numbers and been ok. Just a guideline. In the OP's case, you can maybe try the Blitzking and have more luck instead of buying a different barrel.

Keep in mind, if you are looking for maximum 'splat' factor in prairie dogs say, you want to be as close to possible at the rpm limit based on your velocity, because that increased spin is much more destructive upon impact. I use this list to choose my barrel twist based on the formula provided by Texas10

 

[stretch257]

I run the 50 zmax out of a 22br 8 twist at 3800 without any issues. They sure come apart on the dogs.

 

[rockhound78]

Built it more for our Varmint Silhouette matches. Figured the 53vmax for Prairie dogs(150m), rabbits(200m), and woodchucks(300m), but will try the 52gr Sierra BTHP match and the Hornady 52gr. match and maybe the 55 Nosler BT for the shorter targets, and the Hornady 62gr bthp or Nosler 70gr RDF for the half size pigs(385m) and chickens at 520 yds

stretch257----I have some of the 50 zmax, might give them a try, thanks