So it begins. I sent off my old Sedgley Springfield to JES Reboring earlier this fall and got back a 375 Whelen. I opted for the standard 375 Whelen. It seemed appropriate in the Sedgley. Before anyone swoons over the Sedgley, it had been bubba'd pretty badly with poorly done side and top mount holes for scope bases and the bolt would close on a no go gauge. Plus I wanted a 375 Whelen. The rifle cost me $180 and the rebore $225 so I ended up with a pretty reasonably priced 375 Whelen.

I spent quite a bit of time on line finding bullets to test. I may have gone a little over the top. Missing from the picture are some 250 grain Sierras and 4 more boxes of Hornady 270 grain round nose.



I located 200 rounds of some LC 76 match brass. I already have a 35 Whelen so wanted to avoid any confusion by not using any of that brass. This was all unfired match brass. I used my 30-35 and 35-416 expander die to open it up and then ran it through a CH-4D 375 Whelen die to neck size just enough to make a snug fit in the chamber. I had one split neck out of 200.

I had to trim to 2.220 to square up the mouths. That's a bit shorter than the 35 and 400 Whelen's trim length of 2.495.

My choice of powders was limited to what I had on hand. Powder availability has been sketchy at best here in Alaska. I had plenty of BL-C2, 3031, 4320, AA2495 and some RL15. The RL15 is running low so unless I come across some more it's use in development will come to a halt.

There is precious little data for the standard 375 Whelen. A fair amount exists for the 375 Ackley Whelen and the 375 Hawk/Scoville but not much for the standard version. Data exists however, for most of the same bullet weights in the 35 Whelen. Knowing that the same bullets weights of a larger diameter are going to produce lower pressure given the same loads, I extrapolated data from 35 Whelen data.

My first trip to the range was yesterday and it went well. I was testing Speer 235 grain bullets with the five aforementioned powders. All were primed with Federal 210 primers. I expected this bullet to easily crowd 2600 fps. My BL-C2 loads produced the highest velocity and came the closest to meeting that velocity. It was clear to me that I estimated on the low side of all my test loads. None of the 100 rounds I fired showed any evidence of excessive pressure, no cratered primers, no primer leaks or blown primers and no shiny spots on the base of the case. Bolt opening and extraction were effortless in all loads tested.

The top loads were as follows (I worked up from well below these charges);

BL-C2 62 grains 2574 compressed
2495 54 grains 2324
3031 54 grains 2510
4320 57 grains 2482
RL15 59 grains 2464 lightly compressed

I still have much work to do. I had hoped to sort out one or two powders that showed great promise but they all shot with relatively good accuracy. AA2495 and 4320 showed the best accuracy but not a great deal better than the others. 3031 was a bit inconsistent with accuracy, one good group and the next erratic.

All my initial groups were 4 shot groups at 100 yards. The rifle wears a 24 inch barrel and is scoped with a Leupold 3-9x compact. All loads were shot over my PACT chronograph. I used a PAST recoil shield and a slip on recoil pad to reduce shooter fatigue. It worked very well. I was tired from the recoil but not sore after 100 rounds.

I will continues to post more as I have more data.

Mart

I do not find your rifle interesting, as it is not left-handed. Just kidding

Good luck with your load development.

What level of accuracy did you get? What is your goal?

George

The rifle was a 1.5 to 2" gun before the rebore. It is doing the same now with some loads going into a little less. I am happy with anything under two inches from a hunting rifle. It's great to get those little one hole clusters. Who doesn't like that? I am also realistic about the actual requirements in the field. This is 300 yard and under rifle. Anything grouping two inches or less is fine with me.

I wish it was left handed. I have been looking for just the right rifle to build a 375 Whelen on and then it dawned on me that I already had one. It may not be quite perfect with it's bolt on the wrong side but this rebore put an otherwise unused rifle back in service.

Mart

And it will be easier to sell than a lefty rifle.

George

I keep looking for a lefty youngster to mentor that might end up with some cool left handed rifles. Otherwise it's going to be tough to sell some of my odd ones when that day comes.

If you'd like, I can run some quickload calculations for you. You'll need to give me some data to work with. What is your water capacity of the case, what will the OAL be with each bullet, and what pressure do you want max loads at?

Tyler,

Water capacity to the top of the neck is 70.3 grains. I was told by a guy on the Campfire that Quickload has the 375 Whelen in it's database. I really need to buy Quickload and start using it.

OAL with the Speer 235 grain is 3.150. With the 270 grain Hornady SP which I'll be trying next is 3.330. I have a theory that 3.330 is the optimum OAL for all Whelen cartridges. It works well with both the 35 and 400 Whelen. We'll see if it pans out for the 375.

As far as max pressure I don't see much need to go past 50,000.

Mart

Using your data, and a 50k PSI limit here is some data with common powders. Use at your own risk obviously.

Speer 235 grainer:

Accurate 2495, 55 grains, 2560 fps

Reloder 18, 63 grains, 2560 fps

Accurate 2520, 58 grains, 2547 fps

Hornady 270

Reloder 17: 61 grains, 2438 fps

Hodgdon H414: 61 grains, 2387 fps

Winchester 760: same as Hodgdon H414

Accurate 4064: 55.5 grains, 2386 fps

The five powders I listed are what I have available. I did pick up a pound of Benchmark and a pound of IMR 4198 this week. Not much is available here. I am nearly out of RL15 so testing on that is done soon.

Mart

Spent last Tuesday at the range and have a little more data. I started out with bumping up a little on a couple of loads that showed promise previously. I tried 60 grains of RL 15 behind the Speer 235 and came up with 2422 for an average. It was 15 degrees colder last Tuesday than the week before when I made my initial trip to the range with the 375 Whelen. On that trip I got 2464 out of 59 grains of RL 15. Groups from both loads were decent.

Next I took the BL-C2 load up another grain to 63 grains. The 62 grain load grouped well at 2574. With 63 grains it was 2613 and lousy grouping. I tried some heavier loads of 4320 and got an awesome group at 58 grains with the Speer 235 at 2522, 59 was slower than the 58 grains and poor grouping and 60 grains was good again but only 2548. I'll do more work with the 58 grain load. AA2495 turned in velocities from 2288-2438 with charges from 55-58 grains. Grouping was mediocre. Benchmark turned in good velocities but horrible groups.

Moving up to the Hornady 270 grain with BL-C2 I got very good groups at 56 grains with 2325 fps. I tried up to 58 grains but that load was too hot. I had good luck with 4320. It turned in good groups from 52-56 grains with velocities from 2135 to 2344. Same was true for AA2495 with loads from 53-57 and velocities from 2176 to 2329. I tested one load of 54 grains of RL15 but only recorded one shot as light was becoming and issue. Accuracy was good and the only velocity I recorded was 2316. I'll need to work more with that load.

It looks like the 375 Whelen is going to want to run about 2500-2550 with 235 grain bullets and around 2300-2350 with 270 grainers. I would expect 250's to run in the 2450 range and 300's to be around 2150-2200. I still have a lot of testing to do. It's going to be a few weeks before I can get back out but will update when I have more to report.

It was interesting that with it slightly colder the AA2495 turned in lower velocities with the Speer 235 than the lighter loads from a week before. Same was true for RL15. Curious.

Mart

The cold probably slowed your trigger finger down, thus the lower velocity. Next time yank that trigger faster.

Mart,
I really like the idea of 250-grainers at 2450 fps in the .375 Whelen.

Sierra 250-grainers, Swift 250-grainers, from soft to tough,
and the do it all:
.375/250-grain Barnes TTSX to turn that .375 Whelen into a Sheep Rifle.





.375/200-grain GSC HV will be a better NonCon than the CEB 230-grain brass bullet with plastic tip,
since the latter takes up a lot of case, and the band pattern is so limiting to loading length choices.

quote:

Originally posted by roughone:
The cold probably slowed your trigger finger down, thus the lower velocity. Next time yank that trigger faster.

Maybe.

My experience in the .375 WBY:
IMR-4350 slowed down about 2 fps for every 1 degree F temperature drop.
RL-15 was about 1 fps.
H4350 Extreme was only about 0.5 fps.

quote:

Originally posted by roughone:
The cold probably slowed your trigger finger down, thus the lower velocity. Next time yank that trigger faster.

I never thought of that. I'll give it a try next time. Would greasing the bullets help get the velocities up.