And So It Begins - .375 WSM Project

[Llama Bob]

I am a big fan of the WSM cartridges. They give lots of power in a short action with the same magazine capacity as belted magnums in a long/magnum action. The case capacity to be gained simply by ditching the stupid belt is substantial. The only real criticism I can see is that the WSMs top out at 8mm. There's no good reason for this - the .338, .358, .375, .416 and .458 WSM all work just fine and were quickly wildcatted after the original cartridges came out.

One of these in particular seems exceptionally useful: the .375 WSM. For general big game hunting when bears might be present, it's hard to imagine a more suitable round. It is capable of the same performance as typical factory .375 H&H loads (300gr @ 2400 ft/s) while within SAAMI spec, and in a suitable rifle could be used for any dangerous game applications you would use the H&H for.

I'm in the process of simplifying my hunting rifle collection, and as part of this I want one big thumper with at least some reach that I can use for elk in bear country, predator call bear hunts, and possibly African or other applications. The goal is to do this at a reasonable price - have the entire gun and loading setup (excluding consumables) without optics for < $2000. This should be very doable by reboring a gun.

As a starting point, I chose a New Haven Winchester model 70 classic in .270 WSM. This has several harder to change things already right about it:

• controlled feed and Mauser claw style extraction
• 3 position safety
• open-style trigger
• WSM feed geometry
• sufficient barrel diameter to rebore to .375 WSM

The plan is to send it to JES reboring after inspection and have it rebored and the barrel cut and crowned at either 20" or 22" - I haven't decided yet. In addition to the reboring, the stock & bottom metal will have to be replaced, and express sights, bases and rings added. Along with dies from CH4D, this should stay well inside the budget.

Initial QuickLoad sims suggest that in a 22" barrel exceeding factory .375 H&H is possible with compressed loads of temp-insensitive powers (RL-23 or RL-16) and factory loads can be matched with an uncompressed temp-insensitive load (H4895).


Each inch of barrel costs about 25 ft/s, so I could still match factory loads with a 20" if I was willing to compress. I don't have to make the barrel length decision for a bit...

 

[LoonWulf]

Very cool project, and im looking forward to watching it happen!

Also looking forward to seeing more flavors of 375's out in the wild!

 

[Llama Bob]

In terms of ballistics, for elk mountain conditions, maximum PBR (6" circle) with a 300gr A-Frame is 243y. Maximum range where a hit can be nearly guaranteed on a 12" plate with +-3 MPH wind call error and a 1.5 MOA hold is 390y. This is almost entirely a function of wind call error - reducing the hold to 1.0 MOA buys only an additional 10 yards. Swift claims the A-Frame initiates expansion at 1650 ft/s, which this hits at about 460y. In practice though it looks like 1750 ft/s or so expands much better which is at 360y. So the range at which expansion occurs is about the same as the range at which hits can be guaranteed.

So basically this will work without much thought out to 250y or so, and out to 400y with a careful hold. That's plenty for a rifle that's basically a thumper at heart.

 

[troy fairweather]

Yes very cool project, I've thought to do something similar. I always liked the wsm rounds. The 375 would be a great companion cartridge to my 7wsm. I'd go 22in can always be cut down.

 

[jmr40]

It seems that no one, even most manufacturers, missed the whole point of the WSM cartridges. There were a lot of factors that came into play that limited their success. Most notably IMO is the lack of rifles designed around the cartridges advantages.

I like them and think they are very much misunderstood and under rated. I've always felt they may have been introduced before shooters were ready for them. Maybe that will change. Good luck with your project. I don't need one, but like the concept. I also never understood the 325 WSM when there were so many better bullet options for a 338 WSM. Maybe going to 375 will get someone's attention.

 

[Llama Bob]

It seems that no one, even most manufacturers, missed the whole point of the WSM cartridges. There were a lot of factors that came into play that limited their success. Most notably IMO is the lack of rifles designed around the cartridges advantages.

I like them and think they are very much misunderstood and under rated. I've always felt they may have been introduced before shooters were ready for them. Maybe that will change. Good luck with your project. I don't need one, but like the concept. I also never understood the 325 WSM when there were so many better bullet options for a 338 WSM. Maybe going to 375 will get someone's attention.

I suspect it's a situation like with the 10mm handgun cartridge, where it was an obvious and worthwhile development that the market didn't "get" and didn't make many guns for and a lot of the guns sucked. Then it became a cult of people snatching up Delta Elites and eventually the prices went out of control. Then guns started being made again and it became mainstream.

I think we're in the 2nd stage - people snatching up M70 and Kimber 8400 WSM actions still at reasonable prices, but you can see them vanishing from the market.

 

[Llama Bob]

Just out of curiosity I looked, and there are zero 7mm WSM Kimbers or MRCs for sale across the major sites. There's one CRF winchester that they want $1450 for, and another as part of a collectible set that they want $20K for. And one push feed Winchester and a M77mk2. And that's IT.

These are weird times, but they're weirder for WSMs. it took me a couple weeks to find this one rebore candidate at a decent price when before there would have been 20 options.

 

[Llama Bob]

Yes very cool project, I've thought to do something similar. I always liked the wsm rounds. The 375 would be a great companion cartridge to my 7wsm. I'd go 22in can always be cut down.

I think the 7mm was a really inspired idea. I've hunted mine quite a bit. I have switched over to a .300 WSM for a smallbore just because the 200gr Terminal Ascent is such an incredible mix of BC and terminal performance across impact velocities. The 7mm Terminal Ascent seemed a hair low SD to me, although I'm sure it's actually fine.

 

[Riomouse911]

I recall CDNN was practically giving away Model 70 .325 WSM rifles about two-three years ago...they had them advertised for months before they sold them all. I guess no one wanted them because the 8mm bore size in a magnum rifle seems about a popular as the .422 of the .404 Jeffery to North American hunters. I think a .338 or .375 WSM would've been a bigger hit.

The stubby .375 WSM you're assembling sounds like a winner, keep us apprised of your progress .

Stay safe.

 

[troy fairweather]

I think the 7mm was a really inspired idea. I've hunted mine quite a bit. I have switched over to a .300 WSM for a smallbore just because the 200gr Terminal Ascent is such an incredible mix of BC and terminal performance across impact velocities. The 7mm Terminal Ascent seemed a hair low SD to me, although I'm sure it's actually fine.

Is the terminal ascent the newest bullet or the old, think I remember the new one has more realistic b.c. Is like to try some of I can get some 6.5 or 7mms. Dad bought 3 Browning abolts when they came out, the 300 was nice and shot good, the 270 was just behind the 300 not many 270 bullets then. The 7mm was insanely accurate that one I kept, dad had a savage striker 7wsm had the same Inherent accuracy. very fun to shoot he even shot his bison with it though I wanted him to used the new bfr 45-70 he had.

My brother still has the 270 I keep trying to get off him cheap, he has not hunted in 15 years.

 

[Llama Bob]

I recall CDNN was practically giving away Model 70 .325 WSM rifles about two-three years ago...they had them advertised for months before they sold them all. I guess no one wanted them because the 8mm bore size in a magnum rifle seems about a popular as the .422 of the .404 Jeffery to North American hunters. I think a .338 or .375 WSM would've been a bigger hit.

The stubby .375 WSM you're assembling sounds like a winner, keep us apprised of your progress .

Stay safe.

The 325 WSM is an odd one. I've owned two, but never shot at game with either - it just never worked out. The 8mm bullet supply is not that broad. But strangely both the .325 M70 sporter and featherweight are still cataloged while the 7mm WSM was eliminated. I suspect there are slow but steady sales as essentially the only short action magnum medium bore commercially available (.338 RCM seems dead). I'm sure people in bear territory look at the 220gr A-Frame and find it comforting. Of course the .375 300gr A-Frame is more comforting, but I'm going to have to go to some lengths before I can get one of those down the barrel.

They should have made the .338 WSM. Supposedly they couldn't figure out how to match factory .338WM ballistics, but that looks like a load of malarkey if QuickLoad is to be believed. it looks like both RL-16 and H4831SC get the job done with no or little compression and low temp sensitivity. Somehow they missed the boat.

 

[Llama Bob]

Is the terminal ascent the newest bullet or the old, think I remember the new one has more realistic b.c. Is like to try some of I can get some 6.5 or 7mms. Dad bought 3 Browning abolts when they came out, the 300 was nice and shot good, the 270 was just behind the 300 not many 270 bullets then. The 7mm was insanely accurate that one I kept, dad had a savage striker 7wsm had the same Inherent accuracy. very fun to shoot he even shot his bison with it though I wanted him to used the new bfr 45-70 he had.

My brother still has the 270 I keep trying to get off him cheap, he has not hunted in 15 years.

The Terminal Ascent line is Federal's latest take on a low drag Bonded Bear Claw. The previous was the Edge TLR, which they pulled from the market pretty fast. I have some TLRs but have never loaded them. The Terminal Ascent is well behaved despite the stupid name

 

[troy fairweather]

The Terminal Ascent line is Federal's latest take on a low drag Bonded Bear Claw. The previous was the Edge TLR, which they pulled from the market pretty fast. I have some TLRs but have never loaded them. The Terminal Ascent is well behaved despite the stupid name

Strange they are not keeping these bullets, I was looking into the edge then one day they were just gone. I think if the price was less more guys would shoot them, every thing about them looks good. Didn't they add a extra grove to the new ones. I'd like to see fed/speer make more gold dots, even tho they say there not for hunting or something like that but ever test I've seen looks like a great hunting bullet.
I am still on the search for a do all bullet for my 7mms, the 150 accubond maybe it.

 

[Llama Bob]

I tried a few and settled on the 175gr A-Frame. It's one of the only A-Frames with a decent BC and of course great terminal performance. The tipped bullets are a bit better drag-wise, but in that small a bore not much.

 

[H&Hhunter]

I read about some .375 WSM conversions back in the day. The .375 Ruger pretty much solved all of the “issues” that the belt and magnum length case of the .375 H&H presented. So you don’t see to many .375 WSM’s around.

 

[jmr40]

The problem with the 325 WSM is that it shot the same bullet weights as the 300 WSM and shot them to virtually the same speeds. You might find 20-30 fps difference depending on the source, but that isn't enough to matter. And in the same bullet weights the 300 WSM would always shoot faster, flatter downrange and penetrate deeper due to the better bullet options. There have always been better choices in 338. When Ruger introduced their line of short mags their 338 RCM was the best of the bunch.

 

[Llama Bob]

The problem with the 325 WSM is that it shot the same bullet weights as the 300 WSM and shot them to virtually the same speeds. You might find 20-30 fps difference depending on the source, but that isn't enough to matter. And in the same bullet weights the 300 WSM would always shoot faster, flatter downrange and penetrate deeper due to the better bullet options. There have always been better choices in 338. When Ruger introduced their line of short mags their 338 RCM was the best of the bunch.

You would certainly expect them to shoot the same bullets at the same weight, given that they have the same case capacity. Energy is energy, and powder energy density doesn't change much with burn rate. The advantage of the 8mm bore is basically bullets one weight step heavier. For example, the heaviest A-Frame in .323 is 220. The heaviest in .308 is 200. Same goes for the spire point Woodleighs. Hawk offers their "round tip" pointed bullets in 8mm up to 280gr, but only up to 250 gr in .308.

Of course there are other good bullets like the Terminal Ascent that exist in .308 but not .323 or that don't have a 220gr .323 like Partitions. If there was a 220gr TA in .323 I'd probably be using my 325 WSMs.

I think the RCM lost too much performance to refusing to have a rebated rim. In any case, good bad or indifferent it looks dead.

I read about some .375 WSM conversions back in the day. The .375 Ruger pretty much solved all of the “issues” that the belt and magnum length case of the .375 H&H presented. So you don’t see to many .375 WSM’s around.

The reasons to go .375 WSM are 1) short action 2) existing rifles with WSM feed geometry and 3) brass

Hornady is the only source of 375 Ruger brass, and they appear to do limited runs. There are at least five production sources and six brands of WSM brass: Winchester, Norma/Nosler, Federal, Hornady, and Bertram.

Regardless of any merits it may have, the .375 Ruger seems at least temporarily out of action due to ammo, component and rifle unavailability. A comeback may happen but the M77 being the primary rifle platform may hinder that.

 

[horsemen61]

Awesome project I can’t wait to see it finished!

 

[Nature Boy]

I recall CDNN was practically giving away Model 70 .325 WSM rifles about two-three years ago...they had them advertised for months before they sold them all.

I stared at them almost daily. Had one in my cart a few times but never executed the transaction. I just wanted the action for another project so it really didn’t make any sense. Having said that, I still have a twinge of regret not snagging one at those prices.

 

[Riomouse911]

I hear you. CDNN has tempted me numerous times. They had reasonably priced Win Model 70 Safari’s in .375 H&H and .416 Rem Mags for a while...I just couldn’t justify the cost of buying a big magnum, scope and all the reloading stuff they entail. (For all intents and purposes I’ll really never need one.)

But they sure looked nice!

Stay safe.

 

[Llama Bob]

Two steps forward and a step back...

Ch4D had the dies in stock. They seem to be good to deal with and I recommend them - I used them for my .50-110 as well.

But I did something dumb. I know good and well to remove the decapping pin when necking up/down brass because you're using so much force it's easy to bend stuff. Did I do the right thing? Nope. I bent the bejesus out of the decapping rod instead. This is my fault, not CH4Ds.

I also clearly need to use sizing wax for these. I've got some on the way and I have another CH4D decapping rod. But I did manage to make sort of one piece of brass. I don't think it's very concentric, but here's at least a look at what's coming:


It looks so tiny, but there's enough space there to drive a 300gr at 2400, and that's something... maybe everything if you've got a bear problem.

I've spent a bit more time with quickload trying to answer the 20" vs 22" barrel question. It looks like I can get H&H velocities with H4895 even with a 20" barrel and a monolithic solid (which takes up more space). So that's the route I'm going to go. I think the 20" will be very handy and fast.

I bought 2 sets of PTG Obendorf-style bottom metal for M70s. One is going on my .300 WSM. The other will maybe go on this rifle. These are very well made IMO - a perfect, tight fit to the existing mag box, action, and the Bell and Carlson stock I intend to use. They do seem to take up a little more vertical space than the two piece factory part however. With the factory bottom metal loading 3+1 is comfortable. With the PTG, you can do it but there's too much friction extracting the first round. I'm not really a fan of doing +1 since I'd prefer the extractor NOT be able to pop over the rim. But the factory extractors on these M70s can, so it's potentially an option. My thinking right now is to stick with the PTG metal and load 3 and possibly fit a new extractor eventually.

I really like the way the Obendorf style metal protects against dropping all your rounds on the ground. Very well thought out IMO.

 

[Llama Bob]

It's sort of hard to imagine these are ballistic twins:


Of course the WSM does it using modern powers, and the H&H velocities were set using cordite. But there's more disadvantages than advantages to overdriving the bullets here. So for practical purposes, they do the same thing.

 

[DocRock]

Seems like a lot of work and expense to get to a cartridge that falls just shy of the 375 Ruger. Cool project in any event. Nice rifle.

 

[Llama Bob]

Seems like a lot of work and expense to get to a cartridge that falls just shy of the 375 Ruger. Cool project in any event. Nice rifle.

Getting a .375 Ruger in a correctly functioning CRF rifle would be more expensive, not less, as it would require either converting a very scarce M77 to true CRF or rebarreling something and fixing the feed geometry. And the end result would be a heavier, longer rifle. And not actually be feasible at the moment due to there being no brass.

Unless they get another brass vendor ASAP or at least Hornady prioritizes it more, the .375 Ruger is effectively dead.

 

[DocRock]

Getting a .375 Ruger in a correctly functioning CRF rifle would be more expensive, not less, as it would require either converting a very scarce M77 to true CRF or rebarreling something and fixing the feed geometry. And the end result would be a heavier, longer rifle. And not actually be feasible at the moment due to there being no brass.

Unless they get another brass vendor ASAP or at least Hornady prioritizes it more, the .375 Ruger is effectively dead.

That’s funny. The guy making his own brass is all huffy and adamant the 375 Ruger is dead. But I suppose those hard charging death-elk do merit all the effort because without absolute CRF, who knows what could happen