6mm K Hornet

[Nobade]

Anybody make one of these? I'm thinking 1:10 twist barrel, and the RCBS 95 grain cast borerider over a case full of lil'gun. Ought to be good for at least 1700 fps I'd guess. Seems like a good use of a CZ 527 action.

[kirkwhitaker]

you are just looking for something to build all the time!! might be neat..and with the little 55gr vmaxes...it might pop something pretty hard too...probably in the 2400fps range...neat..
drop a line when you can
kw

[Reed1911]

1:10 :shock: ?
Really fast for a light 6mm, but the neat thing is you could make a 6mm sub-sonic really eaisly with that set-up. A 6mm 105g bullet at about 1050:)
257Ft-Lbs

[Nobade]

Yep, you read my mind....

[kirkwhitaker]

plan to do with it? how are you going to set the gun up if you do it?  i do think those "little" rounds like that are neat...the 270 ren is neat too...
anyhows....have a good weekend...
kirk

[HillClimber]

. . .should be a bit tighter for the long 6mm.  That 10T will probably work with a 70gr. spitzer and maybe a 90gr. WC.  You need RPM for stabilization, more for longer projectiles.  

Recall the failure of the .244 Rem. because it wouldn't work with bullets above 90gr.?  The .243 Win. stole it's lunch (with slightly less powder capacity) by successfully using 100gr. spitzers.  The Hornady 105gr 6mm bullets are roundnose (shorter for the weight) so they can be used in a 12T @ 3K FPS.

Bottom line is that you need a twist to give you enough turns at 1050 FPS to stabilize that long bullet.  You might need a gain-twist to physically do it.  There are a couple of formulae to figure this (I just don't have one handy).

John

[Reed1911]

A 1:10 is more than enough to stabilize a 120g 6mm bullet, you are correct in your history that the 6mm Rem failed initially due to it's 1:14 twist, when the .243 Win came out having a 1:12 twist helped its ability to use the heavier bullets.
Gain twist is a very tricky animal and very few people really know how to use it. The only production gun I know of off hand that uses it is the .500 S&W, and only to allow the use of hard cast.
For those of you who might be scratching their heads, gain twist is just what it sounds like. The breech end of the barrel starts at one twist rate (lets say 1:16) and as you move toward the muzzle the gain progressively gets faster (lets say 1:10 at the muzzle). It allows you push heavy for caliber at higher speeds with out shearing of the jacket. For most calibers it's unnecessary and it can cause serious headaches to get a barrel set up right.

[Nobade]

I didn't know the .500 used gain twist. I had read the .460 was - starts at 1:100 and ends up around 1:14. Sounds like it would be awful with cast bullets, since the shape of the rifling imprint on the bullet would change and cause gas to leak past.

As for the .243's twist, it takes 1:8 to stabilize 107 VLD bullets, but normal 100gr. hunting type bullets are fine in 1:10. I shoot a lot of the RCBS 100gr. cast boreriders, and they work fine in my 1:10 .243 down to 500 fps, and up to 2600 fps.

[roper]

There was a round call 6x29.5 Stahl cases made from 22Hornet milled down load was an 6mm 85gr cast bullet 7gr/2400 velocity 1460fps.  Using the Hornet case as is you gain alittle more case capacity don't know if it would be offset by the heavier bullet you want to use.  I would think the 1/10 twist barrel should work.