IMR VS Hodgon Reloads 4350, 4831

[MikeMarcum]

Hello,
This is my 1st post here. It is not news that reloading supplies are limited to say the least. I have a somewhat simple question but have not found any direct answers on the links here, ( or anyewhere else) please redirect me if I am wrong. I am an experienced reloader (35+ years but trying to get the science of it down), but with mainly pistol and smaller rifles that are more recent & popular loads that there is a ton of published data for. I am most likely over thinking this, but here it goes.

1. I have a great Pre-64 Model 70 in .375 Weatherby Magnum I inherited from my Dad. I really want to use it on a hunt this year. It is a field grade hunting rifle, but Factory Ammo is out of the question - 6 bucks a round and only in 300gr - OUCH on the Shoulder and Wallet - really bad!

2. I have multiple manual (including recent One Book / One Caliber). Have been web searching but all sources only give data for Hodgdon Powders.

3. After much waiting in lines (mostly left stores empty handed) I was able to get 1 lb. each of some IMR 4350 and IMR 4831. I am trying to work up loads with Hornady Interlock SP 225 gr. (4350) and Hornady Interlock SPRN 270 gr. (4831)

4. Unless I find some 215 primers I am stuck using Remington 9 1/2 Large Rifle Primers. I just fire-formed & Weighed New 375 H&H Hornady Brass as well.

4. Does anyone have a formula or something I can use to set myself up with starting loads for a conversion? With the pretty heavy recoil and lack of reliable supplies I cannot afford to test shoot dozens of work up loads from way too weak to acceptable. Plus do not want to break myself or the Rifle - safety 1st.

5. I have checked other Magnum Rifles for comparison, my Manuals show about a 9-10% reduction for IMR 4831 in a 378 Weatherby with a 270gr. And about a 2-3% Reduction for IMR 4350 vs H4350. Thus my plan is to use the same % in my 375 Weatherby Hodgdon Data.

6. I am thinking right? I am not looking for MAX loads, but accurate Hunting Loads to 400-500 yards.

I have found more than one thread about the pros and cons of both powders, and about Magnum vs STD Large Rifle primers, but not comparisons of load amounts. Since I can not find any other powder I can not use the testing I have always used in my other guns. Plus at 90ish grains per load I get only about 75 reloads out of a pound.

Thanks for all the great reading on other posts and hope we all get tags this year and have ammo to use them!

 

[roninflag]

what are you shooting at?. i would not use anything but magnum primers.

 

[MikeMarcum]

I would normally only use magnum primers, but in N. Nevada I have not seen any in 6 months. It is like getting Concert Tickets at my local shops, 300 plus people in line 90 minutes before stores open the day after they get stock. Thus my Large vs. Magnum dilemma + Powder choices are so limited to seem like I am shopping in the old USSR. No gun ban needed if you can not find ammo or reloading supplies, it does not make a good club.

If I make the draw 225 gr for Mule Deer, 270 for ELK - Ok I know these are a bit of overkill, but this was my Dad's Gun that I have loved since I was too little to shoot it and really want to use it and share the harvest with him while He is still here. His health is not so good and would like to put a big smile on his face knowing "HIS" rifle did the job.

The 225 at a light loading of 2900 FPS at 5000+ ft altitudes here in N. Nevada that leaves me with over 1600 ft.lbs and 10.3 moa drop at 500 yards

 

[roninflag]

have loaded the 375hh and 378 wm. we have taken elk , zebra and other stuff with the 270 horn sp. i used varget in the 375hh ; my buddy shot a lot of animals with it. can not remember what used in the 378 neither were my guns. weatheerby IMR , nosler hogdon someone has data. dont extrapolate. you may get more info over on 24hourcampfire. luckily you are not hunting next week, mean time find some mag primers. ron

 

[MikeMarcum]

Thx Ron for the reply

 

[backwoods83]

The most likely problem you will have with the 375wby/225grn/4350 load is you will run out of powder space, same with the 270grn/4831 load. The 225 load would do better with Varget, 4064, 4320, 4007ssc, etc.. the 270grn load would be top notch with Imr 4350 and a standard primer will light off 4350 or 4831 just fine, although with that much powder I do prefer WLRP as they are about the hottest standard primer except the russian wolf/Tull stuff. Both of your loads will be highly compressed with your powder options. The 375 H&H calls for a compressed load of H380 under a 235grn pill and it operates 3k psi lower than the wby, just as an example.

 

[MikeMarcum]

One again, Thanks for the info. If and when I can get any other powder I will as well as Magnum Primers, if and when the supply chain returns to semi normal. I think the IMR 4831 will not be as bad as H4831 as the load will be decreased 10%.

I am not planning on using 378 load data, just looking at something else big that has load data for both IMR and Hodgdon powder and ratios they are using. Trying to figure out good starting point for what stuff I can find.

 

[backwoods83]

Start with near max loads for the 375 H&H mag and go up a half grain at a time. But as I mentioned earlier, unless you find accuracy loads at slow velocities, your loads will be tightly compressed, the 375 H&H shows 80grns of Imr4350 compressed under a 270grn pill and I believe 83grns with 4831, and yes Imr4831 is much faster than H4831. I doubt you'd ever need anything as slow as H4831 unless your shooting 350grn SMKs.

 

[MikeMarcum]

That was my fall back position, to fall back to H& H load data and work up, but since powder and primers seem to be so darn rare I was hoping to get there in a few less loads. I really hope to get some supplies before it really counts. I have been over the web and printed books for over 3 months now trying to get a good starting point. The Rifle is more than powerful enough for anything here in Nevada, even at H&H velocities but hoping for a little flatter drop. As well as trying to maximize my powder rations. And since I have never shot 225 in it before, have no idea on accuracy. I have some older reloads for 235, 285 and 300s that I got from Dad when he gave me the rifle. But no real documentation and 4 or 5 kinds of brass. But after about 10 rounds of full load 285 and 6 more of the 300 my shoulder was complaining about the recoil. Not my favorite bench rest rifle.

My Manual ( One Book / One Caliber Vol 2 Weatherby Copyrighted 2004)shows for the:

225 HDY SP with starting loads of 96 gr. of H4831 for 2813 fps - up to 99 gr Compressed for 2957 fps.

In H4350 shows a starting load of 89 gr at 2939 fps and max out at 94 gr. and 3070 fps. ( no compression listed for the H4350) and

Thus since I do not have any of the H to compare to the IMR for volume. They show up on burn rate but have not seen anything to show volume to weight data.

The Hodgdon Website shows Data for H&H with both 4350 types and compressed loads of 83 gr for H4350 and compressed IMR 4350 of 79 gr. but for a 250 gr bullet. at .5 grain that is a bunch of rounds to get to 90 or so, but I may have no other choice.

Thanks for the help, it may just be time to drive a bunch and go to a few gun shows to find known loads powder. If it was just a matter of cost and shoulder pain I would try lots of loads and powders, I love to geek out on data and love to shoot. there is lots of good places here as Nevada is mainly empty BLM land and mountains everywhere so good backstop are never an issue. Most of my Reloading is for Cowboy Action 45 Colt and Varmint rounds, the CAS is not so hard and 22 centerfire is not 375.

I was hoping for an accurate load of about 2900 fps (225gr BC .320) as my new Scope is the Redfield Revenge with the DNS Accuranger and at my altitude (5000 ft.) using the Hornady Website Ballistics Calculator it should match the drop of the 243 dial almost perfectly to 500 yards (zero MOA difference to 300 yds., 0.1 at 400 and 0.3 at 500 - the dial uses 100 yard zero)

Have fun and hope to hear more from anybody on this issue. I have the list of acceptable powders in my wallet so if I can find anything anywhere I am ready to try, at least 375 bullets are not as impossible to find like 22 or 30 cal.

 

[backwoods83]

I dug up some data for the 270grn Speer over Imr4350 it shows max load at 82grns, i'd start at 79.5 and load 6 or 7 rounds up in .5grn increments to save powder. It shows a velocity of 2867fps at max charge. Sorry no data for the 235grn except with 4064 and 4320.

 

[MikeMarcum]

Thanks again, I will follow up when I get to the range and report back, heading out this weekend for my Mom's birthday so no range time till next week.