Guys,

A question about RE15, just how temprature sensitive is this powder?

I thought I had my 375 H&H loads figured out using RE15 powder. Now after today I don't think so.

I was at the range today and had some heavy bolt lift, etc.

Components common to both loads.

Winchester brass, Fed 215 primers

270gr. Hornady (#3715) Interlock RN soft with 75.5gr. RE15

300gr. Hornady (#3720) Interlock RN soft with 70.5gr RE15.

Part of the reason I went to the range was to chronograph several new loads, and check on the 375 older Hornaday bullets loads as a baseline for the new Interbond bullet(s). Well I forgot the chrono so don't have any clue on what the velocities where.

I developed these loads a couple of years ago but it was quite a bit cooler, about 50 F. There where no pressure signs at all then.

Today it was mid 80s and the gun rack at the range was in the sun. Normally there isn't much sun around here (Seattle area) but there was today. After a couple of rounds I noticed a very stiff bolt lift for both bullet weights. Also I couldn't get the bolt to re-close on a piece of fired brass, which says to me way TOO much pressure. Everything (primers, brass, bullets, powder, gun) is the same except temp. Though it is possible the powder might be a different lot, I don't think it is.

Is RE15 really so temprature sensitive that a near max. load (but not over pressure) goes to way over pressure with about 30 to 50 degrees difference? What would it do in Africa where it gets really hot?

Thanks for your time .

Roi

Those are stiff loads.

All powders show increased pressure with elevated temperatures. That is why most ammo manufacturers don't put out "hot" loads (notable exceptions are Weatherby and the newer short magnum loads). RL-15 is actually one of the more temperature stable powders going. That is why the military uses it as the propellant in M118 LR sniper ammunition.

People call me a puss a lot, but I generally max out at 71-72 grains for the 270 grain bullets, and 67-68 grains for the 300 grain bullets; more for lead core bullets, less for monmetal shanked bullets.

Back off two grains on each load and you will be shitting in tall cotton. Those are very good bullets. They weren't designed to be pushed at "max".

Pushing things to "max" is what earned Remington a bad reputation for its 416 Rem Mag ammunition throughout the 1990's. Everyont backed off 2-3 grains, and now it all works peachy.

If you really want the velocity, open your chamber up for the 375 Weatherby. You can use H-4350 and pick up 150 fps on the 375 H&H while still having some air space in the case.

FWIW, IMO, my $0.02 worth, BTT, BLT, YMMV, DWTFYW, ciao,

LD

520wells

I'm not sure where you got your load data but both of those loads are over Max looking at my data.

I heard the US military adopted R15 as the powder of choice for the 308 cartridge just because of its behavior in temp extreems. I tend to think you might be seeing a difference in lot to lot variation if you didn`t work up with a new lot.
Your loads do appear to be a couple tenths over max in what I see for data also as Jay reports.

Hornady #5 375 H&H

270 gr Hornady RN/ 62.7-74.3 gr R15/WLR primer/ Win case/ COL 3.605

300 gr Hornady RN/ same conponents/ 56.8-70.1 gr R15

Hey Wells
I am currently working on a load for my 375 H&H using RE-15 and 300 grain Barnes TSX. This morning I shot several different loads of the above combo. Temps were about 80 degrees. I shot 70, 71, 72, and 73 grains and easy bolt lift on all and no pressure signs at all.
By the way I shot a 3 shot .5" group with 71 grains of RE-15 and 300 grain Barnes TSX!
I think my gun likes 71. I will re-shoot 72 and 73 grains tomorrow as I was getting pounded a bit with my light rifle I will go as high as 74 grains and those are very compressed loads.
You may look at your scale or seating depth somethings not right if you are having that kind of trouble, maybe you are up tight against the lands?