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375 H&H

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03 April 2004, 06:52
hm1996
375 H&H
Have been working up loads for a post 64 Mod 70 Win. and 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 shots 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.

Regards,
hm
03 April 2004, 09:15
GeorgeS
That's pretty good. Which powder(s) are you using?

Both .375H&Hs I've owned shot very well, and both shot solids and softs to almost the same POI.

George
03 April 2004, 09:23
fredj338
That's a great group, but it does look a wee bit over .240" if ea. small square is 1/4". Just want to keep you honest, groups are measured from ctr. to ctr. What were the load specifics?
03 April 2004, 13:21
hm1996
George:

Using IMR 4064 with all bullets.



Fredj338:

OK, Fred, you caught me! I re-measured the group and came up with .2425". All joking aside, the only way I could measure was to flatten the target (close up the bullet holes) and measure outside dia. of the printed black circle left by the bullets @ widest point then subtract bullet dia. (.6175 - .375) Am I missing something?



As for the load used:

68 gr w/300 gr. Sierra BT produced av. vel. of 2493 fps.*



69.6 gr. w/300 gr. A-Frame for av. vel of 2488 fps*



69.0 gr. w/300 gr. Nos. Part. for av. vel. of 2452 fps*



(*Screens were about 15' from muzzle)



Note: These loads are above maximum listed loads in my loading manuals. While they produced no signs of excessive pressure in MY rifle, YOUR mileage may vary. Approach with caution!



Regards,

hm
03 April 2004, 13:35
fredj338
I have also had good luck w/ 4064 in severak .375h&hs I've tried. I am currently w/o one, someday I'll have to get one to match up w/ my M70 in .404, and then a .300h&h just to balance it all out.
03 April 2004, 14:34
GeorgeS
I use W760 and AA MRP (like IMR4831) exclusively.

Great results, consistently.

George
03 April 2004, 14:36
hm1996
Quote:

I have also had good luck w/ 4064 in severak .375h&hs I've tried.



Found it strange that my Sierra loading manual was the only one showing 4064 for the 375 but stated it was the powder for 300 gr. bullets. I like a powder that fills the case and 4064 does that in the 375.

Regards,
hm
03 April 2004, 14:55
hm1996
Quote:

it does look a wee bit over .240" if ea. small square is 1/4".



By golly, you're right, Fred! The group did look larger than 1/4" so I've been tryin' to figure out where I went wrong on the original measurement. Measured one of the single bullet holes in the target & the black ring only measures .342", not .375, thus the group was actually .2755" (OD of group was .6125" less .342" = .2755")

Keep me honest, guys.

Regards,
hm
03 April 2004, 17:34
fredj338
Yeh, got to watch the big bore guys. They all like to exagerate the size of things.
03 April 2004, 19:18
Mike375
If I am reading your posting correctly then something that would make me question your rifle/load setup (if I owned ikt) is the big change in point of impact for only a .2 grain change in the load. Also the 270 grain load going over 4 inches to the left. Are the loads with +.2 and -.2 grains using the same brass, same sizing method?

Mike
04 April 2004, 08:36
hm1996
Mike375:
Quote:

Also the 270 grain load going over 4 inches to the left. Are the loads with +.2 and -.2 grains using the same brass, same sizing method?




Sorry, should have cropped the 270 gr. shot out of pic. to avoid any confusion. Can understand where you are coming from. I was fireforming some new cases and shot the 270 grain loads at the left hand square. It really is not that far from POI of the 3 shot group had it been fired at the same target.

The five shots were all in once fired WW cases prepared the same. The first (high) shot was from a clean (patched) bore. Last shot (low one) is where it is, maybe some shooter error?? Plan to load a larger batch & get back to the range for more extensive testing as soon as this bloomin' wind lays.

Regards,
hm