No wonder the 375 H&H has been around so long!

[hps1]

Have been working up loads for a post 64 Mod 70 Win. and just had to share the latest target.

This rifle shoots groups with 300 gr. Sierra BT, Swift A-Frame and Nosler partions that are all centered within 3/4" of rifle zero (1" high @ 100 yds).
All group MOA if shooter does his part.

The following target was shot with 300 gr Noslers. Shot @ left was a different (270 gr. load). The highest shot was .2 gr lighter than the three shot group 1" high @ 12 o'clock and the shot dead center was .2 gr. heavier. The 3 shot group measured .240" as best as I could measure it!

Funny thing about this rifle, the lighter the load, the higher the 100 yd. impact; as load increases, POI drops. As the maximum load is approached, group tightens up no matter what bullet is used.

Aren't accurate rifles fun?

Regards,
hps


--------------------
Keep 'em in the X; Hold tight, jerk right.

 

[BigG]

I've had a couple groups that were one-holer.

 

[HankB]

I find it very strange that you're getting the POI changes you are with a variation in (presumably) powder charge of two tenths of a grain.

There's not enough data - go out and shoot some more!

What was the load, by the way?

 

[Badger Arms]

There's not enough data - go out and shoot some more!

Words to live by.

 

[hps1]

There's not enough data - go out and shoot some more!

Now that's good advice, Hank! Now if the darn wind will lay. Blew all night and getting stronger.

Regards,
hps

 

[Al Thompson]

The slower the velocity, the later the bullet exits the barrel. Hence the higher strike on the target.

 

[hps1]

That makes sense. The 2400-2500 fps MV would make this even more noticeable. Guess that is why I hadn't picked up on that angle before shooting much faster cartridges.

Thanks, Al. The more I learn about reloading, the less I KNOW!

Maybe you can help me with another quirk I noticed. I never crimp my reloads, but the 375 recoil pushes the bullets back into case of rounds in magazine. Started crimping and found crimped rounds averaged 30fps loss of velocity compared to uncrimped. Hope I'm not straying too far off topic here.

Regards,
hps

 

[Cosmoline]

I'm really getting to like my CZ 550 in .375. The recoil isn't that bad at all. Certainly nothing compared with my old 1895G with hot .45-70's.

Besides all you have to do to dissuade attack with one is show the cartridge to your foe. Those things are like Saturn V rockets!

 

[Al Thompson]

30fps is pretty tight. IMHO, this is in the realm of SD for reloads.

How many did you chrono?

 

[HankB]

In my .375, I don't depend only on crimp - I also rely on a tight case neck. To do this, I removed the expander ball from my RCBS dies and just size the case. Then I use a modified Lyman "M" expander - I turned it to a smaller diameter, so it doesn't expand the neck - and just put a tiny flare on the case mouth so I can start the bullet.

Hmmm . . . I'll have to try Noslers again. I've been using Swifts since they shoot more accurately in my rifle, but you can't argue with three shots in one hole. (I'll keep five rounds inside an inch, but seldom will I put three consecutive rounds through the same hole. Especially if someone else is watching. )

What WAS that load?

 

[hps1]

Al:
I did only shoot 10 rounds (5 crimped/5 not), but the crimped rounds were consistently lower MV than the non crimped rounds and these loads had very low SD (2.6) w/extreme spread of only 5.1 fps. Guess this may be one of life's little mysteries concerning reloading.

Hank:

Well, Hank, the wife was in the truck reading the newspaper, but she was not watching. Had she, or anyone else been wathching, the group would have opened up, I am sure.

What WAS that load?

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.

This rifle consistently produces lower MV than that posted in the loading manuals for a given load. This load exceeds the max. listed in my Sierra manual and it is the only book I have showing 4064 for the 300 gr. 375.

Load was in once fired WW brass, Fed. 215 primer, 69 grains of IMR 4064
behind the 300 gr. Nos. part.


Two factors may enter into the lower velocity??: 1) This particular lot of 4064 has been on my shelf for several years. 2) The Noslers had been moly coated and tumbled to remove the moly coat. They are copper color but may have traces of moly in the pores of the jacket. If any moly remained, could result in lower pressures/velocity????

I am getting 1" from the A-Frames as well. Haven't shot too many groups as I am just getting the load worked out. Did notice the A-Frames mike only .3745 where the Sierra & Nosler bullets mike .375. This may be why the A-Frames slipped in the case.

Regards,
hps

 

[HankB]

hps1 - I haven't tried 4064 in my .375, but it works wonders for match loads in my M1A. Usually I use Winchester 760 - oddly enough, the measured velocities out of my rifle's 24" barrel with this powder match, or sometimes exceed, the handbook velocities, which is very unusual in my experience. (I have a Belgian-made Browning Safari.)

It's interesting to note that neither Winchester nor Remington 300 grain loads break 2400 ft/sec, though they claim 2550. I figure when my handloads actually DELIVER what the factories CLAIM, I'm doing OK . . . especially when there are NO signs of excess pressure.

And I'm still surprised at the POI changes that two tenths of a grain of powder produce. I guess every rifle is a law unto itself.

 

[hps1]

Hank:

I haven't tried 4064 in my .375, but it works wonders for match loads in my M1A.

Interesting. The reason I had 8# canister of 4064 on hand was that I tried it in my 30-06 bolt gun with 190 gr. Sierra matchkings and never did get results I was looking for. Finally found a load that this rifle liked using H450 w/the 190 gr. MK's for the long range matches. The 4064 may work better in a 308.

It's interesting to note that neither Winchester nor Remington 300 grain loads break 2400 ft/sec, though they claim 2550.

Have found many factory velocity claims do not check out in my rifle(s). I suspect they use a 26" test barrel to obtain a little better velocity than we can get from hunting rifles. Either that or they measure their velocities closer to the muzzle than we can. My screens are set up about 15' downrange. Anyone know a formula for converting to a true muzzle velocity? Would imagine that if possible to measure closer to the muzzle, would indicate slightly higher velocity. Remington posts a 2530 fps MV for their premium 300 gr. A-Frame load and the best I can get w/4064 is 2488. Any increase in powder starts to show early signs of high pressure.

If you decide to experiment with 4064 in your 375, let us know your results.

 

[BigG]

4064 is THE powder for 375 H&H. Produces one hole groups if caffeine levels are controlled.