Twist rates for rimfire

J

jGEE

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Anyone have thoughts on twist rate and temperatures for rimfire???

I read on another site a fews days ago -one poster seemed pretty adamant about twist rates for rimfire in colder weather. I think his name was Roger and thoughts were in colder weather 14 twist rates are more stable than the common 1 in 16 for rimfire.

Rodger was saying as the outside temperatures increased slower twist rates could be used, maybe 1 in 19 for 90-100 degree weather would increase stability.

I ask because i was shooting my 141/2 twist barrel the other day and it was in the high 50's maybe 60 degrees. The barrel shot better than i remembered back in the summer time. I must say my memory is not the best either- so really not too sure.

Now the question came to my mind- can twist rates be used for accuracy tuning in different temperatures?... joe :)
 
Dam good question Joe- Maybe the learned will have an answer. garrisone.
 
Joe, the anschutz fortner biathlon is 1 in 14 they advertise it's accuracy to -20 degrees.
 
Perhaps a gain-twist would be the answer, just cut a little off the front as the temperature goes down .......................................................................;)
 
Then glue it back on as it warms up. You would have to chamber the muzzle end to be directionally correct. Hey! maybe chamber both ends and just reverse ends for different temps. You might be on to something
 
There was a big to-do a few years back when the Eley EPS nipple nose round came out - everyone was so excited - until they started getting keyholes from 1:17 twist barrels in cold weather.
 
This may not mean anything......

Not sure if the formula is correct, but I thought it was interesting.
I always heard about the 1:17s in cold weather (never owned one myself)
Wonder if Bullet RPM is a factor...not spinning enough maybe equals not stabilizing?

BulletRPM.jpg


And back to Joe's question...can it spin too much?

And then add the part about maybe warmer/moister air is thinner air and maybe colder/dryer air is thicker air.
Does that maybe play on the rotation?

Probably don't mean nothing, but kind of interesting just the same.
 
Vibe said:
Everyone needs to look at this at least once.

http://www.nennstiel-ruprecht.de/bullfly/
Click to expand...

thanks for the link... I looked at the yaw part a while back during the brief discussion of yaw... I barely understand what i'm looking at but i'm getting some of it.

One thing i don't think it is in there but something flashed in my brain... Without "spin" i think the bullet would just tumble... Ok we have spin and the bullet stays concentric... Does the tumbling forces go away or they just held in check by spin? (this should be in a new thread) ....joe
 
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Jeffrey, very interesting, I never saw a chart like this before. Since 16 twist is standard, I wonder if that RPM rate is optimal? didn't Remington come out with a target rifle a few yrs ago with a 14 twist, I wondered about the reasoning behind that too? Thanks, Douglas
 
Douglas said:
Jeffrey, very interesting, I never saw a chart like this before. Since 16 twist is standard, I wonder if that RPM rate is optimal? didn't Remington come out with a target rifle a few yrs ago with a 14 twist, I wondered about the reasoning behind that too? Thanks, Douglas
Click to expand...

They did that because they already had the tooling.....seriously, nothing more. Nobody over there can recall ever hearing a serious motive behind it. They generally did only fair.
 
martyh said:
Joe, the anschutz fortner biathlon is 1 in 14 they advertise it's accuracy to -20 degrees.
Click to expand...

Marty brought up an interesting point, to -20 degrees and the rifle is a 14 twist...

tim brings up a good point about Remington's 14 twist
They generally did only fair.
Click to expand...

In the European countrys i would say there is a lot more rimfire competition in below freezing weather.... did Remington build a cold weather rifle and we shot it in the wrong weather?????

Anshultz building a 14twist for cold weather makes me think there is something to tuning a rife with twist rate.

I don't think we shoot many matches over here in weather below freezing.... joe
 
It is interesting that the twist rate for the .22 short liners from Redman's is 1:20. Don't know what value this information is other than to further confuse the issue.
 
Not an expert, but I always assumed this is why many older match guns, such as 40x's and 52's had such long barrels. And Anschutz as well possibly.....

Anyway, I assumed that the longer barrel would tend to stabilize a wider range of bullets in a wider range of temperatures.
 
In relation to comment about Euro mfg units, how about the older Suhls some of those have 1-19 twists as well as 1-17.

I have a 1-17 on my 40x, but as far as cold vs/warm/ hot weather, there are so many other variables I can not give a definitive answer.
 
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