what kinda speed could be ?

[pety221]

me an a freind were talking the other day
if u take a 7mm rum an necked it down to 6mm what kinda speed would it be running when it left the barrel ?

 

[.444 Marlin]

Depends on the bullet weight and barrel length.
100gr....roughly 3450-3600fps if you could get all of that powder to burn.

 

[Sniper]

I would say you would be in the 3800-4000 range but your barrel is not going to last long. I would say after 300 rounds you may see an accuracy loss. Would probably need a 28-30" barrel to get the max velocity.

If I did not already have a 257 Weatherby the 257 STW might be interesting, I have not fooled around much with anything less than .25 caliber.

 

[.444 Marlin]

What would be really nasty is necking a .338RUM down to 6mm........

 

[TiminTN]

I think the 06 case is plenty big for that bore. The 240 Weatherby is equal to the 6mm/06. I have a wildcat off the 338 RUM case and it is necked to 7mm. I think that case is a better choice than the 7mm RUM.

 

[.444 Marlin]

I think the 06 case is plenty big for that bore. The 240 Weatherby is equal to the 6mm/06. I have a wildcat off the 338 RUM case and it is necked to 7mm. I think that case is a better choice than the 7mm RUM.

And I still dont know what the difference is between a 7mm/338RUM and a 7mmRUM.

 

[TiminTN]

Not much. The 338 RUM case is .090" shorter. This allows a properly set up reamer, cut a chamber to have a loaded round be able to fit the magazine AND reach the rifling. This is not possible on a 7 or 300 RUM.

 

[Whelen Man]

The 338 RUM has a slightly shorter length to the shoulder than the 300 RUM. It supposedly had to do with the bullet seating depth for the heavier 338 caliber bullets to be seated out long and still work in the standard length action.

Tim you beat me to the draw on this one.

 

[pety221]

DA what u building ?