Maximum Velocity for 90 gr. Sierra MK

[eggman]

Does anyone know what Sierra suggests as the maximum velocity for the 224 90 gr. SMK. That is before it comes apart in flight.

Rodney

 

[jadams]

EGGMAN: Re: .22 90 gn. Sierra
I don't know what Sierra suggests as the maximum.
But,I can tell you what my experiences are.
I shoot a .2247L 30" 1 in 8" twist and I find that at Sea
level and above 70º the Sierra's will come apart pretty
consistantaly at 3460 fps. Also the much aligned Berger
90 gn. will come apart at 3440. Not much difference in my
opinion. At these velocity's they will not work in a 1 in
7" twist ! I'm now have a new Broughton 1 in 9" twist 30"
installed and hope to find out what they will tolerate.

It is surprising to see how accurate they can be at 600 yards as they are on the threshold of blowing up.
John

 

[mikecr]

Jadams
Great info on the breaking point of these bullets. I take it you've bounced off that wall a few times.

I put together a rule of thumb for Berger, that I doubt they'll regard. Anyway, it predicts 'the wall' fairly well.
Try it:

KRPM LIMIT =,0.308-cal)*238.095+290
Velocity Limit then equals 1.38889*KRPMlimit*TWIST

So for the 90 berger:
KRPM LIMIT = 310
Max Velocity = 3,444fps

The velocity limit from a 9tw barrel would be 3,875fps. But it's irrelevent, cuz A 9twist ain't gonna stabilize a 90smk,this side of Montana in a heat wave).

 

[eggman]

Thanks for the very useful information. I was hoping I would get "real world" information. Looks like I'll be just fine I have just started load development for a new 30" 22 Dasher Hart barrel in 7" twist. I usually never pushed 80 gr. SMK's over 3400 from a 28" barrel so I don't think I'll ever approach 3400 with the 90's. It looks like my sweet spot is going to be just over 3200 fps but I haven't tested that far yet waiting on the weather to cooperate. I had trouble stabilizing the 90 gr. bullets with my 8" twist Hart barrel so this time I went with a 7" twist.I think Hart's 8" twist is really 8.2"or something like that.

Thanks,
Rodney

 

[eggman]

I'm pretty sure I won't be hitting that wall. My best load so far shooting naked 90 gr. SMK's is running 3233 fps with temps in the low 30's. I tried N-550 and H-4350 and so far H-4350 performed the best at 35.0 grs. with the bullet seated .004 into the lands. I still have more work to do with seating depth and I want to give the Berger 90 gr. VLD a try as well.

Rodney