.308 to 300WSM

[Go Cougs]

I have a Savage Model 10 that has an ER Shaw .308 Winchester heavy barrel with 1 in 10 twist. I am thinking of re-chambering the barrel to 300 Winchester Short Mag.
I’ve already converted the bottom metal to accept AICS mags. So I’m aware that I would need to change the bolt head and purchase new AICS mags to fit the new cartridge.

Has anyone had any success doing this?

Will the short action magazine be able to handle the longer bullets I may want to use?

I’m really just trying to get more velocity out of my 30 cal without buying a whole new rifle.

 

[Long Range 338]

Running the Short Magnums is always a challenge. You can make it work if you know your bullet and can custom throat the barrel to fit the bullet at your maximum cartridge length. The problem ends up being that you can't get enough powder into the case to take full advantage of the bc of the heavier bullets.

Many end up running the short magnums in a long action or single feeding to get the ballistic performance they seek.

 

[kyzim311]

The question is what is what is your goal?

The short action mags will limit your OAL, so the real heavies will be a challenge. Long action is the way to go for long range WSMs, but it will still give you way more than your 308. You can also single feed heavies for range shooting with 200+ grain bullets if you want to max out the performance. It might not matter if you just want a bit more than 308.

 

[Ronws]

Sounds like a neat project.

I would probably just get a Savage 110 in .300 WSM.

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Just an example of where you get one, especially if you really like Savage. They also have Christensen Arms at a steeper price but many people like their quality, too.

edited to add: you can also find some without an included scope so that you can put on whatever you like.

 

[b6graham]

probably cheaper/same cost to just get a prefit

 

[Ronws]

probably cheaper/same cost to just get a prefit

I ilke that idea, too. Build with the parts that you want, instead of getting a cheap stock you will remove and shove in a corner in a closet or cabinet. I have only done that on days that end in the letter 'y'.

 

[wvfarrier]

I am pondering the same change on a Savage 10BA Stealth.

 

[AMMOWASTER]

Are there any strength concerns? I think Savage used the Large Shank barrels on the short mags.

 

[SonoranPrecision]

Are there any strength concerns? I think Savage used the Large Shank barrels on the short mags.

Most, if not all, custom actions that use savage threads are using the small shank threads. It will be fine.

For what it’s worth, I run a 300 wsm in a short action. From a 20 in barrel I’m getting 2700 FPS with 208 eldm’s and h4350.
One thing to pay attention to is the throat dimensions of your gunsmith’s reamer. I believe the SAAMI 300wsm chamber has literally zero freebore. My chamber has enough freebore to run the eldms at 3.010 oal or something close to that. Currently I’m at 2.950 and it’s shooting phenomenally. There’s definitely a lot of bullet below the neck, but picking the right powder can help to optimize the suboptimal.

 

[Chickentoast]

^My 24" 308 gets 2640 with a 208 eld-m. The WSM is neutered most by barrel length, second by COAL. A WSM with a 10 twist 24-26" barrel, and a long throat - could run a nice mag length 155 load and a single shot 208 or 215, for a sweet do-it-all rig.

 

[SonoranPrecision]

^My 24" 308 gets 2640 with a 208 eld-m. The WSM is neutered most by barrel length, second by COAL. A WSM with a 10 twist 24-26" barrel, and a long throat - could run a nice mag length 155 load and a single shot 208 or 215, for a sweet do-it-all rig.

While I don’t disagree, it’s worth noting/clarifying that I had the 208s up to about 2850 before any real indicators of over pressure. I picked a lower velocity to optimize impact velocity for hunting. It’s the same reason I run a 7-08 with 180 eldms at 2540.

That said, I think running 180’s up over 3000, or 168’s around 3200 is where the wsm is optimized in a short action

 

[Jackomason]

For this purpose I really think a tikka action is the way to go.

That or grab some copper solids for when you need the extra preformance.

There should always be a moment of pause when it comes to spending money on a savage but that's really your decision.

I'm running an origin with multiple barrels and wish I had the extra length of a LA or medium. But really the preformace step up to a short mag of what ever flavor is still there regardless of magazine limitations. You just don't have all the freedoms of a Long action.

 

[Long Range 338]

I’ve only got factory rifles in 300 WSM but have had good success as long as I stay under 200 Gr bullets. BC isn’t quite as good but I can fit magazine length and decent velocity

 

[Go Cougs]

Thank you gentlemen, for all of your input.