brass and pressure question?

[lsm62]

I had a good load worked up for my 300 Weatherby. It's on the hot side, pushing 208gr at 3100fps with light extractor marks using Weatherby brass. Decided to try out some Hornady brass as it is easier to find and a little cheaper. Loaded them up, took them out and blew the primers out on 4 out of 5. Packed up and went home.

Variables:

Weatherby brass being resized by just bumping the shoulder back .002. Hornady set from factory.(let a friend barrow my head-space gauge so i don't know the difference between the two)

Neck tension. Somebody didn't run the brass through the resizing die before loading it.(I am kicking myself for this, I Know better)

Zero temperature 80F, 26.6C. Shooting today 100F, 37.7C

Any Ideas on what to do next?

Should I buck up and stick with Weatherby brass? Drop a half a grain, expand the brass and try again? Or rework my load for less pressure?

 

[varmintH8R]

What powder are you running? That 20F can make a huge difference, especially if your loaded rounds have some time to sit in the sun.

My personal approach would be to back off the load regardless of brass used. You are seeing slight pressure signs in the Wby brass, so any number of factors could create an issue (new lot powder, different primer, bullet seated long, temperature, etc). I like velocity but view it relative to repeatability, safety, and brass life. With the velocities you are running, my opinion is that there are diminishing returns for running at the very high-end of pressure. Basically, the benefits of the extra velocity (at that weight/velocity, basically extra energy waaaaaaaay out there) are outweighed by potential issues (blowing out primers, a major oh-crap, breaking something in the field, etc).

Good luck an be safe!

 

[lsm62]

too true probably back down a couple grains and work back up.

 

[Lefty7mmstw]

You've got to back that puppy off a bit my friend. Take her down 10% and work back to a good load. I won't load anything that puts marks on the brass when it fires.

How's your primer pocket life? gun)You shouldn't be loosing pockets or your loads are to warm.

 

[blksno]

Check the H2O volume of each case. I'm betting it's WAY different.

I had the same problem with Win vs Nosler Comp brass in my 300 SAUM.

Bought 67 piece of once fired Nosler Comp cause its already weight sorted and very consistent. Tried the same charge as I was using with Win brass and was ripping rims off the cases. (gas gun)
Everything else the same and the Nosler Comp brass couldn't take the charge.
Dropped the charge down 1.2gr (IIRC) to get equal velocities.

 

[lsm62]

thanks guys much appreciated. Ill probably save the brass back and use it with some 185 VLDs or something.

 

[RT2506]

If you will read any loading manual it will tell you when you change ANYTHING in a load you need to back off on the powder and work back up.

When you are driving down the road and you see a STOP sign do you keep on going right through the intersection just because you have a cool breeze blowing through the window and you don't want to loose the feeling? Same principle for when you start getting "slight ejector marks" on a case. That is the STOP sign because you are ALREADY OVER PRESSURE. You may make it through the STOP sign a few times OK but one day there will be a trailer truck coming and smash you to pulp. Not trying to be a smart a** just trying to wake you up to the danger possible to you and your weapon.

 

[mrultramag]

I have found that wby brass in general is greater in volume than other makes of brass for the wby cartridges. The wby brass can be loaded with a heavier powder charge where as the other brand of brass will reach those same pressures/velocity with a lesser charge of powder. Try running full tilt 257 wby charges in some converted w-w 7mm mag brass that's been fireformed. normally can reach the velocity with at least 2 grains less powder in the W-W brass compared to the wby brass.