1:9 twist ?

[boxhitch]

Is there a factory rifle built with this fast twist ?
Green Mountain Has a barrel available, but where in Canada

 

[ben hunchak]

Is this for a .22 Rf.? Isn't the 1-9" for a central fire cart. as no rimfire .22 would flourish with this fast twist as no bullets are long enough for it, IMHO.

 

[HeavyT]

Just got a S&W MP15 that came with a 17" 1-9 twist match barrel.

 

[mmattockx]

Is this for a .22 Rf.? Isn't the 1-9" for a central fire cart. as no rimfire .22 would flourish with this fast twist as no bullets are long enough for it, IMHO.

+1. 1:16 will stabilize .22LR bullets. There is no gain to be had in overstabilizing a bullet, if anything the accuracy will drop off a bit.

Mark

 

[boxhitch]

Looking at using the Aquila ammo with a 60 gr. pill requiring a faster twist rate.
Something in the range of 1:9 to 1:12 would probably hold these better than standard twists.

 

[ciphery]

Google search "Greenhill Formula"
You input your bullets dimensions do some simple math and come up with an appropriate twist rate.
Hope this helps
I think its something like;
Bullet length in 0.000"÷bullet Dia. In 0.000"=A
150÷A=B
B x Bullet Dia. In 0.000"=1 turn in ? Inches.

 

[ciphery]

If you have too fast a twist rate you can strip the bullet or even cause it to grenade under the centrifugal force.

 

[Splatter]

The 60 bullet on the SSS is about the same length as the 36 grain Barnes Varmint Grenade.
And the "long" 60 grain SSS bullet seems to stabilize just fine in my 1:16 barrels.

 

[super7]

I think the remington nylon 66 had a 1:9 ?

 

[ben hunchak]

When a soft lead bullet first strikes the rifling, it may prefer a gentle twist and not hit such an abrupt twist which in some cases can cause the bullet to skid somewhat, not conducive to good accuracy. The only way to check on this would be to look at a retrieved bullet, for skid marks or even any widening of the land markings on the bullet.

 

[boxhitch]

.223 running at much higher velocities are using 1:9, but then the bullet construction is different too
Wonder how large speed differences effects the greenhill formula
The 60 gr are keyholing in two rifles I have tried.

 

[trevj]

You have a steady source for these? (Aquila SSS)

Care to share the source?

Cheers
Trev

 

[boxhitch]

Have a few for testing and like the results so far. Just wondering where to go at this point, to make thing sbetter or drop the idea.

 

[trevj]

Get back to us when you have a steady source and can share same. Lots of folk looking for the ammo.

The two main problems are that the ammo is not on the 'approved for import' list, and that the distributor (in the US, and holding the rights to the North American marketplace), last I had heard, was not at all interested in paying the fees required to be able to legally export the product line from the US of A.

Essentially makes this a bit of mental masturbation, or, in the worst case, a waste of funds building a firearm for ammo that you cannot readily obtain.

Like I said, if you have a legal source, there are a pile of guys looking.

Cheers
Trev