338WSM; 300 or 7mm parent case

[Skimbleshanks]

I want to put together a rifle in the wildcat cambering of 338 WSM. I know that it isn't a long range hammer but it would meet a few needs(wants) that I have. See what the WSM family is all about, fill a caliber gap in my safe, use some rifle components I have laying around, simple way to get into wildcat cartridges with out being too exotic. I don't know if I want to use the 300wsm case as the parent or to use the 7WSM with its ever so slightly longer body and I am assuming a smidgen more capacity. What I want to do is push 210-225 grain bullets out of a 28 inch barrel at close to 3000fps. I know Kirby Allen has an XP chambered as such and would welcome his input as well as any of the other extremely knowledgeable people who frequent this board. If you don't lump yourself into the extremely knowledgeable category but have something to say by all means do so. Everyone's help is very much appreciated.

 

[skip300]

What about using the .325 WSM case? Or just use it instead?

 

[winmag]

You are correct about the ever so slightly larger 7wsm case, however I think what skip just posted makes the most sense for necking up, 325wsm makes more sense. .284 to .338 would be very hard on a case neck. .308 to .338 is more easily achieved, but (325wsm/8mm) .323 to .338 is one pass thru the die, and I would think that would promote much better case life and ease you into wildcatting with a few less steps.
Ive thought about this very project, and that is what I would do if it were me. Unfortunately I dont currently have the funds to give it a go, or Id try one with you.
Looking forward to seeing how it turns out. Good Luck

 

[Skimbleshanks]

I've heard lots of good things about the 325 WSM but I already have a rock creek 338 barrel laying about and want to use it. That and it isn't a wildcat which for some reason I really want for my next rifle. What about a 338-300 WSM improved to the 7WSM body length. Fire forming would be necessary and I'm not sure I want to go that far yet, or if it would even make enough of an improvement to be worth it.

 

[winmag]

No no no, I meant neck the 325wsm brass(wich is .323) up to .338 cal. Its still a wild cat 338, and you can use your barrel, but its just alot easier on case necks to go from big(323) to bigger(338) vs. small(284) to big(338).

It would be for all intents and purposes a 338-325shortmag

 

[bb204]

I'm pretty sure I have been told that the 300WSM has a longer neck than the 7WSM.

 

[geargrinder]

I'm pretty sure I have been told that the 300WSM has a longer neck than the 7WSM.

That's correct, but the 7mm case has more powder capacity.

 

[Skimbleshanks]

Win mag I thought Skip was talking about using the straight 325WSM, I get how using the 325 case would be real easy to neck up and I am considering that option seriously. 300 and 325 cases have the same length from the base to the origin of the shoulder (i think, I'll have to double check that one). If so then the 338-300 and 338-325 are really the same animal. Is Winchester/Olin the only manufacturer of 325 brass? I may be persuaded by the Norma brass for the 300. Once again thanks for all the help guys. Oh and don't hold your breath to see results as I am a regular guy with a regular job. I will be getting the action shortly then I need to wait a little bit before I call McMillan, wait a real long time, get a Jewell trigger, match striker assembly, and Wyatts extended mag box, wait some more and find a smith to chamber it all up for me. Anybody have any work done by Darrell Holland. He is in my state and I am considering him but haven't heard much from his customers. Kirby Allen or Shawn Carlock would do an out standing job I have no doubt.

 

[Kiwi Greg]

I am in the process of building a 338-7mmwsm.
I had a 7mmwsm & have sold it but I still have a lot of brass new & fired as well as the dies.
No one wanted to buy the brass & dies so I thought I would use it to build a small 338.
I already have an Edge & a Lapua, which is going to be an AI very soon & I have another Std Lapua coming, so I thought why not be greedy & make a WSM lightbulb
The 7mmwsm brass is longer to the shoulder than the 300 & I have already modified my dies & have formed some cases with very little trouble.
I will be firing 160-225 bullets but I'm sure I won't be able to help myself & I will try some 300s
The donor rifle only has a 24" barrel so velocities won't be outstanding but then they don't have too be.
If it works I may build a better one out of other bits & pieces I have that are waiting to be used.

 

[skip300]

I did say use the .325 WSM instead of a wild cat but I did not realise you already had a .338 barrel to work with.

But I did also say that the .325 WSM would be a better option for necking a WSM cases to .338.

Sorry for any confusion.

Problem with the WSMs I have found is the weight of the bullet is limited because of its length reducing powder capacity. If you have a longer action then you should be able to get around this problem.

 

[Skimbleshanks]

I plan on using a Wyatts extended magazine box so 3.000 inches shoulden't be a problem and I don't plan on using the really long 338 bullets. How is the 325 brass quality wise? Just sort and cull as needed to be good to go?