Anyone have one? I have been considering having one built but was wanting some info first. What type of performance could I expect?

Thanks!

I have one. Building another as soon as my Montana Rifles action is here.

Performance? A bit less than a 338 Win Mag, a bit more than a 338/'06. Mine has taken two elk. On game the performance is about the same as the Win Mag. Instant drops. What more do you need or want to know?

Try this link. http://www.huntamerica.com/wwwthreads/showflat.php?Cat=&Board=UBB13&Number=53194&page=&view=&sb=&o=&fpart=1&vc=1

Or go to HuntAmerica and do a "SEARCH" under 338 WSM. Lots of info posted in very old threads.

[ 02-09-2003, 09:14: Message edited by: Bob338 ]

Thanks for the info. I maybe emailing you in the future for some more info if that is ok.

I have two of the Montana actions on order and was considering making one of them a 338 WSM.

Gent's, it may be of interest that Kimber is bringing out a new CRF action (with three position safety) called the M 8400... it's designed for the WSM's. It'll be offered in wood/blue as well as a stainless/synthetic version (called "The Montana") which is supposed to weigh 6lbs 2 oz's. Sounds like a good bet as it's the first action designed from the ground up for the WSM's.

BA

I have a Sendero converted to 338/300 WSM. It has a stainless fluted PacNor super match barrel installed. I shoot 180 grain Ballistic tips and get about half to three quarters inch groups all day. My load is 67.5 grains of 4831SC. I have custom dies and loading is as easy as it gets. Lube case necks and run 300 WSM brass through the sizing die and load...one pass. I have not chrono'd yet, but as long as it shoots this well, velocity means nothing to me. I bought it to hunt with, but a bit on the heavy side. I am considering selling it and have my XP 100 rebarrelled for it. Good luck with building one. I have no doubt when the word gets out, this will be a factoy load soon and guns will become available.

Sniper~
Happy to answer any questions you may have. If you do that search mentioned earlier, much is covered there.

I have suggested, to all that will listen, that this be build off the 7wsm, rather than 300 wsm for a couple reasons.
1: The 7 wsm in slightly longer, and would assist in preventing a 338 wsm actually being chambered in a 300 wsm... it COULD fit, and would a little over active slamming the bolt closed, would fire.. with both an oversized bullet in the barrel AND the bullet dislodged and forced into the case. Both of these INCREASE pressure, and the wsm line already runs at 65K

2: since the 7wsm is a tad longer, it'll have a very slight, but measurable, 3 grains or so capacity.

other than that, I think it should be a factory round!!

jeffe

I'll know later this week what the actual water capacity would be for the 338/7mm WSM, but with only .035" longer body, everything else the same, I doubt you'll get the extra 3g water capacity. At that, the hassle of expanding brass two calibers may not be worth it. 300 brass expands easily with no losses. In expanding 7 Rem Mag to 338 Win Mag, I've lost a few cases. To avoid that a 30 caliber expander and doing it in two stages will work, but for a gain of 3g or less, is it worth the hassle? The larger bullets STILL intrude greatly into the powder chamber anyway.

Another factor will be that if and when the factory comes out with a 338, it's likely they will SHORTEN the body rather than lengthening it. The shorter body IS what they tested, then scrapped it because of the lost velocity. That means that to convert the wildcat back to a factory round you'd have to take at least a couple of threads of the barrel. Also, just try to chamber a 338 WSM in the 300. I doubt you could do it even using a sledge hammer.

Bob,
not to be argumentative, but ackley's books are pretty clear on weird things that are possible... so, i'll talk to what I can say
1: if it's a 338wsm was shorter, it would MORE easily go into a 300wsm chamber
2: yes, it's a big jump, but possible. which is why the 450 marlin AND the 7wsm are setup to prevent more than necksize from keeping them in the wrong chamber
3: I same on a guys keychains, what happens with a 416 rem in shot in a 416 rigby, and hanging on the wall what happens when a 308 is shot in a 25-06. I've personally shot 308 in a 358, for "fireforming" as the headspace datum is the same..

accidents happen, and if it's more than just necksize preventing it, then mroe the better..

btw, and for what it's worth, it's only remotely possible to chamber an EMPTY 300wsm brass in a 257x300wsm... and requires an serious attempt... but, people shoot 30/30 in 356, and 303 savage, and/and/and/and... 8 mauser R in 7.62x54r... and get away with it... but why let it go on?
jeffe

Jeff~
We ALWAYS face concerns about chambering cartridges in the wrong rifles, particularly so with those of a cartridge 'family', like 308's, '06's, and most ALL the belted magnums from the H&H family. You can chamber a 350 Rem Mag in several 30 caliber belted case chambers and calibers smaller than 35 and they will easily fire. I'm sure some idiot has done it. Your concern may be valid, but what of the 270 WSM? Based on your concern you could possibly chamber a 300 in it, and someone may do it.

In the case of the 338 I suggest it is NOT a valid concern. The SAAMI dimension of the 300 neck is .345". The exterior diameter of the 338 WSM cartridge, depending on brass thickness, is about .366". You'd have to be a gorilla WITH a sledge hammer, to chamber that round in there. The bullet would pass the chamber neck but I'd love to see you compress the seated bullet .020", or more to get it to chamber. We tried it. You can't do it. You're still much further from chambering when the neck of the brass hits the constriction, than a measly .035" longer body.

I'm still considering a 338/7mm WSM, but only if I could gain much MORE than 3g of water. Not worth the hassle for the very little advantage for me. Besides, I have beaucoup load data already. I'll let you know what the difference is. I'm guessing 2g at best. Brass is on the way now.

Sniper,

I have an XP-100 in 338-300 WSM. I had it built using a Lilja 15" stainless/fluted barrel with 1-12" twist as I do not intend to use bullets over 225 gr out of it.

Performance wise, it is very impressive as it drives the 180 gr Ballistic Tips to 2950 fps nad the 200 gr Ballisitic Tips to right at 2800 fps. The 180 gr pills will AVERAGE 1/2" groups for three ahots at 100 yards. The 200 will do 3/4".

With a single shot firearm, the problem with chambering a 338 WSM in a 300 WSM chamber can be eliminated somply by increasing the oal of the wildcat round.

My XP is throated for an oal of 3.075" woth the 180gr Nosler.

Performance on game has been great, this past big game season I took a doe mule deer at 178 yards and a 350 pound 4x5 mule deer buck at a measured 317 yards. Both were one shot and very quick kills.

Hope you have as goos a luck as I have with my XP, out of a rifle it would be a great round as well.

Good Shooting!!!

50

FWIW-Received the 7mm WSM brass. Expanded both it and the heaviest 300 WSM brass I could find, to 338.

The 7mm brass was identical in neck and body wall thickness to the 300 brass, yet it weighed 8g more @ 229g than the 300 brass which weighed 221g, both without any prep. Both necks were .013" to .016" AFTER expansion. Only thing I can figure is difference in head thickness and in the extractor grooves to account for what I determined.

There was a difference in weight in the dead primers I used to seal the pockets, of .8g, the one in the 7mm being the heavier.

Water capacity? 81.7g EXACTLY for both cases!!!

I'm building the next 338 WSM on the 300 WSM case.

When my Montana WSM action gets made I have to select a caliber for it. Right now my defaut cartridge is the .300 WSM however I have some interest in a .338 WSM or a .358 WSM. If one of those should be standardized I might go to a bigger bore.

I did look at the bullet costs however and the .30 caliber bullets cost a lot less. Most of my shooting is at the range. I have so many rifles now that all the bases are already covered.