[exflatlander]

I don't own or have access to a chronograph, but I have found a load that I like so I thought I would put it out here and see if any of you number-crunchers with the computer programs and slide-rules can figure out some ball-park pressure/velocity/energy numbers for me.

.375 Winchester out of a 20 inch '94 big bore

30 grains of imr 3031, standard Winchester Large Rifle Primer.

260 grain Hard Cast, gas checked and lubed bullet.

Seating to the crimp groove of the bullet created a short over-all length of 2.45 which creates a mildy compressed load.

I test-fired these rounds at a local indoor range and was able to shoot an off-hand 5-shot, 3 inch group at the maximum 25 yard mark.

There seems to be no outward signs of pressure issue except for a little flattening of the primer.

Recoil wasn't much worse than the jacketed 220 grainers.

Anyone have any calculations that might give a few clues - or better yet, can anyone point me towards som resources so I can do this type of figuring myself?

 

[Jack Monteith]

Hi, ex:
Quickload, which is $150, is the best program. I'll try it on my old Powley computer (slide rule type) if you can give me the case capacity in grains of water, with a bullet seated. Weigh a fired case, fill it with water, push a bullet in to the seating depth so the extra water squishes out, wipe off the outside and weigh it again. Give me the length of the bullet too.

Bye
Jack

 

[exflatlander]

Jack,

Thanks for the offer, I will try to post the needed info by tomorrow night.

 

[exflatlander]

Jack,

Here are my crude measurements using Lyman calipers and my lee scale.

Full loaded cartridge - 2.4 (average) in

Empty case - 2.019 in

Bullet length - .991 in

bullet diameter - .376

base of bullet (gas check) to crimp groove - .609 in

water weight of full case - 46.4 gr

water weight to base of bullet 30.01 gr

 

[Jack Monteith]

Hi, ex:
I'm afraid the old Powley Computer can't handle this one. It was designed around ratios of charge to bullet weight in the .30-06 range or 1:3 and your .375 win is about 1:9. Doing a bit of off scale guessing (so don't take this as anything near reliable), I get a prediction of 24 grains of 4198 for 1778 feet per second. Now adjusting for 3031, I get 27.7 grains max. Adjusting for the known error in the Powley equations with straight cases would get your 30 grain load within limits, just. As this is just a wild guess, don't bet your hide on it.

Some of the gents over at Accurate Reloading have Quickload and do run it for others.
http://www.serveroptions.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=forum;f=6;DaysPrune=


Check out this site if you want to see the Powley math. Click on "IMR Powders" in the left side scroll box.
http://www.aeroballisticsonline.com/

Bye
Jack

 

[exflatlander]

Jack,

Thanks for your help.

I think I may be riding the line, but judging from the un-scientific reactions I get (the recoil isn't very bad, the lever doesn't kick open and I see no visible signs of problems with the fired cases) I think I can continue with this load.

The 30 grains is a few grains short of the limits I have found in the Loadbooks USA manual I have - I was just worried that the bullets I am using were seating too deep and causing too much compression.

I'll check into the software you mentioned, thanks again

 

[Alk8944]

xfl,

I'm at a loss to understand what the question is. If you are looking for an estimate of velocity/presssure that is easy, just look in the Lyman Cast Bullet Handbook!

Since you do not indicate what your bullet is, I'll as-sume that it aproximates the lyman #375449 which runs from 260-275 grains depending on alloy.

Taken direct from the book shot in 20" '94 Big Bore.

LOA: 2.560"

Start, 26.2/3031/1484 fps
Max., 32.0/3031/1770 fps

Since you are seating somewhat deeper, I would use your 30 gr. as Max. Velocity will probably be 1675-1750 fps. Since the book lists no pressure figures, and knowing that Lyman is fastidious about showing this data if it is going to be anywhere near maximum which is 50,000# for the .375, I feel safe in as-suming (don't like those ***) the pressures observed were well below that figure.

I attempted to run this in Load fron a Disk which is based on Powley's mathmatics, but as Jack said, it is out of limits for the program.

My last observation is based on experience and common sense and I know you have read this many times. GET A LOADING MANUAL!!!!!!!! If you had the proper manual(s) for the type of loading you are doing this would have been available to you and you wouldn't be guessing. You have apparently violated the first principal of handloading. In this case I care not one bit if this annoys you!!!!!!!!!!!!!!!!!

 

[exflatlander]

Alk8944,

I have several manuals and I know 30 grains is withint the limits for the lyman bullet and the 260 gr rcbs 37-250.

However - since my final length is shorter than normal I came here for additional information

This forum is a place where I can usually find the help I need, like I did from Jack.

I do not use this forum to be patronized by someone like you.

I appreciate the info, but if I have to be ridiculed to get it you can stick it where the wind blows but the sun doesn't shine - please lose the additude

 

[MikeG]

Guys, knock it off -

Alk, I know you meant well, but your post comes across a little harsh. And Ex, please refrain from insults.

Nuf' said.

Thanks Guys.

 

[exflatlander]

I apologize for the indiscretion.