R-15 temp sensitivity + barrel length

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05 December 2009, 00:36

dirklawyer

R-15 temp sensitivity + barrel length

How sensitive is R-15 to the cold, say 50 degrees temp change from 30degrees to 80degrees will there be much of a velocity change.
What kind of velocity change would you expect to get going from a 25inch barrel on a 500 Jeffery to a 22 inch barrel? My quess is 25fps change per inch but again that's a quess.

05 December 2009, 04:52

Ed Scarboro

If it's any help, I chronoed my 470 loads back last spring and at 60 degrees the mv was 2040-2050, at 70-75 degrees the mv was 2140-2150 and at 85+ the mv was 2175-2200. That was 87gr of RL15, Kynoch wad and 500gr Woodleigh softnose.

05 December 2009, 09:03

GarBy

I must say that RL 15 has been one of the worst for temp changes that I've seen. No big deal in a double or big bore in Africa, but I like different powders for the states when hunting in colder weather.....like Varget and H4350...if they work close to my RL 15 loads.

Gary
DRSS
NRA Lifer
SCI
DSC

05 December 2009, 17:54

dirklawyer

quote:
Originally posted by GarBy:
I must say that RL 15 has been one of the worst for temp changes that I've seen. No big deal in a double or big bore in Africa, but I like different powders for the states when hunting in colder weather.....like Varget and H4350...if they work close to my RL 15 loads.

Agreed Gary, Varget is one of the least temperature powders on the market today and it does mimic RL-15 very well.

06 December 2009, 07:19

AfricanHunter

quote:
Originally posted by dirklawyer:
quote:
Originally posted by GarBy:
I must say that RL 15 has been one of the worst for temp changes that I've seen. No big deal in a double or big bore in Africa, but I like different powders for the states when hunting in colder weather.....like Varget and H4350...if they work close to my RL 15 loads.

What about load data in the big nitro express calibers. Any one have a ratio factor to RL-15 or cordite?

Agreed Gary, Varget is one of the least temperature powders on the market today and it does mimic RL-15 very well.

12 December 2009, 08:53

Antlers

quote:
Originally posted by Ed Scarboro:
If it's any help, I chronoed my 470 loads back last spring and at 60 degrees the mv was 2040-2050, at 70-75 degrees the mv was 2140-2150 and at 85+ the mv was 2175-2200. That was 87gr of RL15, Kynoch wad and 500gr Woodleigh softnose.

This is consistent with what I've seen in temp diffs of 60degrees vs 30degrees F.