Thinking about chambering an upcoming project in this beefed up 9.3! Does anyone have any experience with this one? I know its not a whole lot faster then the 9.3x62, but the action I'm using was previously chambered in 35 Brown-Whelen, so I'm guessing it has already had some work done to feed the massively improved case and I'm a bit worried about the tapered and sleek x62 feeding right. Would be a shame to have to send it back to only end up chambering it for the 370 or x64. THe x64 is also a consideration right now, but looking at the data on reloadersnest, it looks like most of the loads are on par (or slower) then the 370 and some just slightly faster. Plus, if I went the x64 route I'd have to do bolt face work that can't be undone and if I ever changed the rifle the only thing I could really do is open it up to a magnum case, got plenty of magnums as it is! Also considered the 376 Steyr as well, as they all seem to be peas in a pod.

This is going to be a coated and synthetic stocked elk rifle, no pretty wood and deep blue for this, which is why I'm not tied to the x62 as well, that cartridge screams classic rifle more then utilitarian.

SO! Can anyone chime in on their experiences? I know its a bit of a rare one but I figured someone here among the many rifle loonies has to have run across this one.

I own two 9.3x64 Brenneke's. Started them before the 370 Sako/9.3x66 came out and the 9.3x62 became such a popular cartridge in the United States.

I went with the Brenneke because it is always compared to the 375 H&H, which is what I was replacing. I just felt that the 375 H&H's that were available at that time were just too heavy of a rifle. So I could build the Brenneke on a standard action, with 375 H&H power. Those are the rifles I will be taking to Africa, IF I ever get there and they are legal for Cape Buffalo where I am hunting.

The 9.3x62 invariably get's brought into the 338-06 vs 35 Whelen vs 9.3x62 debates.

The 370 Sako/9.3x66 is just a new proprietary cartridge that is in the same camp as the 375 H&H.

If you just want a 9.3 something, it makes an awful lot of sense to just go with a 9.3x62. Unless you want/need the extra power, or want something different.

I just got done working up three 286gr loads for my rifles.

I have a 286gr TSX/Banded solid loads that shoot 0.75 to 1.25" in both rifles and to the same POI in each respective rifle. The velocity average for the two loads in both rifle is roughly 2550 fps.

I also have a 286gr Hornady SP load that shoots sub MOA in each rifle for a cheaper practice load. This load is averaging about 2475fps for the two rifles.

I did try and work up some 250gr loads, TSX, Accubond, & Banded solids. I could not get any of those to shoot, and gave up on that weight. 2700fps was easily achievable, and I could get to 2800fps. Just could find a suitable loads from an accuracy standpoint.

I also have some RWS factory 293gr ammo that shoots right around an inch (depends on how I am doing) in both rifles with a velocity of 2550fps.

So I guess I would not sweat the decision too much. Go with your gut and enjoy.

I used a .370/9.3x66 in 2008 on buffalo and elephant in Zimbabwe. In both cases it worked as it should. Elephant--frontal brain shot, down and out. Buffalo--frontal chest shot and two in the caboose going away, down and out in about 50 yards. It's a wonderfully balanced cartridge, but like a lot of the other newly introduced cartridges, I doubt if it will ever achieve the popularity it probably deserves.

Guys, where are you getting brass?

MileHighShooter,

This is the first ever valid case I have heard for the .370 Sako Magnum.

Still - I suggest you first thoroughly investigate the suitability of the 9,3x62. I wonder about the "tapering" you mention; I think it is rather a straight-walled case.
The main motivations for this are ammo/brass availability; load data; and good enough performance for any use you might have.

Should the 62 not be a viable option I'd steer towards the Brenneke despite having to open the bolt face.
I believe you'll have serious problems in finding brass but this is probably also the case with the Sako Magnum which is only loaded by Sako (whose ammo is not available in the U.S., is it?) and Federal. I have my doubts as to how long Federal will load it.... Rifles are only today chambered by Sako (but not by its sister brand Tikka) so I seriously doubt if it will survive.
Brenneke brass and ammo will - despite difficulties and apparent rarity - be available as it's an old German cartridge.

Performance-wise there ought to be little to choose from. The Brenneke ought to be the most powerful as the case capacity is some 15% larger than that of the 62.
The Sako Magnum, being new, can be loaded to very high pressures but I doubt the published power figures for the factory ammo. It is possible that they are valid with the new powders but the figures are way higher than they initially were so one doubts.
That said, power is sufficient in any case (pun intended).

Of these, I only have experience with the 62.
I know of some who have the Sako Magnum. They speak of it highly and why shouldn't they? It's in no way inferior to the 62. But that it would in real life be better than the 62 I have a hard time seeing.

- Lars/Finland

Dave,
I was using Federal factory loads.
Hollis

Lars,

There is one gunsmith here in the USA who was chambering and offering brass for the 9.3x66 Sako, before the 370 came about (Z-Hat Customs). This is actually who I am having do the work as well, the head smith there, Brandon, speaks very highly of it and thinks this would be a great platform. I think that is pretty good praise as I'd assume they would really push their own line of wildcats (the Hawk line). He did mention the 375 Hawk when I pondered the 376 Steyr, but he thinks the 370 is great as well. I'd have to check but I think they're still offering 9.3x66 brass, and since they are identical, I am having (if I go this route) the barrel stamped with both 9.3x66 Sako and 370 Sako Mag...just in case I travel with it, I can use either brass and be ok.

I cannot find any other source of brass, I'm sure Qual-cart is an option but who knows if/when they'd be doing a run of the stuff. I know it is extremely expensive, but my intentions, if Z-hat no longer sells brass, was basically to spend the money on the Federal factory loads as my source of brass. I'm not the biggest fan of Federal brass...but, it is what it is.

I haven't totally discounted the 62, I've been pondering that one for many years. I know some people are pushing well past most load data pressure wise and getting some kick ass performance, it just isn't always easy to find that data haha. I'm interested mostly in the 250-260 weight class of bullets, specifically the TTSX and AccuBond. I know the 62 can push those to around 2550, so if my calculations are correct looking at other loads side by side, the 370 should be pushing those around 2740. Sort of getting 338 Win Mag performance with 2 more shells down the magazine and about 5% less powder.

For those that might not be familiar with the 35 B-W here are some pics I found, its getting close to near JDJ taper/shoulder.

I DID think about keeping it as a 35 B-W, and I still have the barrel for it, but a member here a few years back when I bought the action, sent me a Handloader article on the cartridge, and the forming process is WAY more then I want to deal with. Necking up, necking down to create the false shoulder, fire forming (which apparently didn't always work unless you used FULL HOUSE loads seated hard into the lands) then finally being able to load...ugh, too much work.

Rebore!
To a 400 Whelen !

Boomy, I've been talking with them about the 411 Hawk (400 Whelen Improved). But as the situation sits right now, I don't have the time or resources, or experience, to form my own cartridges. Buying from them is a 100pc min. order and we are probably talking 500$ for custom for my rifle ammo.

But still.....that big bullet is tempting.

A simple observation from the sideline:

One thing AR is famous for is creating a shitstorm in favour of certain new cartridges! for instance: The 375 Ruger above say the 375 H&H. 6% increase in case capacity and suddenly this becomes the best thing ever. Not only is it better it spews bolts of lightning from it's arse !

Now we have this new Sako offering in 9.3 : the 66 above the old 62 and this is just not on, no way1 why would you want a 66 over a 62 ? It has no place, no good etc etc.

For years everyone USA had hard ons for AI cartrdiges, because they had a velocity edge over the non AI version?

I bet you if this thing had Ruger written all over it, perhaps a shorter allbeit fatter case everyone would be screaming for one ?

The logic eludes me?

Alf, how about this logic?

250 Savage/257 Roberts/25-06 OR
257 Roberts/25-06/257 Wby?

308/30-06/300 Mag besides the Wby or RUM?

280 Rem vs 7mm Rem Mag?

These are ALL about the same, some even smaller differences, between the 9.3's I'm looking at. And people have thousands of justifications for the differences in these, and they're all 40 years old on older haha.

I think in this case, the 62/66/64 is best summed up to the 257/25-06/257 Wby debate.

I think the .370 is a great idea. That said, I have a 35 Brown Whelen also. There's a few options to make brass. So far we've used Norma 35 Whelen brass with a .357 pistol bullet jammed into the lands over a charge of Unique. Seemed to work ok. The other option that I would like to try is to get some of the 30-06 basic brass that Z-Hat sells. Should be able to just run it through a sizer and shoot it. But, at $2 apiece, I'll just stick with the Norma or Rem Whelen brass for now. I think I would get a few .370 rounds and at least test your action for feeding. Mine is on a LH Sako AV action and all that was needed was to bend the magazine box a little wider. Feeds as slick as ever but did lose one round in the magazine-only holds four down now.
Good luck with your project.
Steve

Well Steve if you ever want ANOTHER 35 B-W, and want to do it on a 1903, let me know lol I have a barrel you can have cheap.