.300 WSM or .300 Win Mag

[C Ward]

Can't get the velocity with a 338 WM to take advantage of the BC on heavy 338s , even with 250s a WM is at 2550 ish .

With a WM based cartridge a 7 with the .8 BC heavies lays waste to pretty much all else .

[smchop]

Can't get the velocity with a 338 WM to take advantage of the BC on heavy 338s , even with 250s a WM is at 2550 ish .

With a WM based cartridge a 7 with the .8 BC heavies lays waste to pretty much all else .

Sorry, I actually meant a .300 Win Mag, not the .338 Win mag.

[smchop]

So, can a 7mm WSM be built on a short action to shoot the 180's or would it need a LA and LA mags?

[C Ward]

You can build it on a normal WSM size actions . You can get the 2900-2950 velocity range easy enough .

Doing a short mag in a long action allows you to max out the amount of case capacity you can use by allowing a longer OAL so you don't loose as much by having to seat the bullet deeper in the case .

The issue right now with the SAUM and WSM is brass availability . Remington hasn't had reloading brass in damn near a decade now and the Winchester stuff is just starting to show up again . So the only readily available stuff is expensive shitty Nosler brass .

The long action RM and WM brass from Winchester is back in stock at Powder Valley last time I checked , which is cheaper and a harder alloy than the Nosler / Norma junk .

For that reason I'd go long action because without brass you aren't shooting . If I was building a 7 now it would be a long action in 7/300 WM . Same case as the RM but 1/10th of an inch longer for more case capacity and built around the 180 ELDM . That combo easily makes 3000 fps and the Hornady bullets are cheaper and more readily available than the Berger 190s .

Have been shooting the ELDM's in 6.5 and 338 for a year now and they work well .

[C Ward]

The thing with the 230 / 240 GR 30 cal bullets in a win mag chamber is without a custom chamber with the throat pushed way out they are 2600-2650 ish fps .

The military load with the 230s IIRC are stupid hot and not something I'd want to have to support on my own dime .

The 300 WM is probably best used with something in the 200-210 GR range to balance usable velocity and bullet performance .

[smchop]

The thing with the 230 / 240 GR 30 cal bullets in a win mag chamber is without a custom chamber with the throat pushed way out they are 2600-2650 ish fps .

The military load with the 230s IIRC are stupid hot and not something I'd want to have to support on my own dime .

The 300 WM is probably best used with something in the 200-210 GR range to balance usable velocity and bullet performance .

I'm sorry, don't know what you mean "is without a custom chamber"? If one caliber I choose is Win Mag I would probably lean towards the 215's. One of my others I used to run the 208's and I liked the way it performed.

[Delfuego]

7SAUM will do 2900-3000fps with a 180 out of either a short or long action. Long action makes things easier because of magazine length. I got a new 29" barrel, bolt-head and magazines for my Bighorn and screwed it on last week. Not quite as fast as XC's 7/300 WSM, or as sexy looking, but should deliver the mail out to a mile or so. I know Mark Chanlynn has chambered a couple 7SAUM's recently if you need a smith, I can also put you in touch with another is you decide to go that way.

Whichever you decide on, you better come down and shoot that sucker.

[smchop]

7SAUM will do 2900-3000fps with a 180 out of either a short or long action. Long action makes things easier because of magazine length. I got a new 29" barrel, bolt-head and magazines for my Bighorn and screwed it on last week. Not quite as fast as XC's 7/300 WSM, or as sexy looking, but should deliver the mail out to a mile or so. I know Mark Chanlynn has chambered a couple 7SAUM's recently if you need a smith, I can also put you in touch with another is you decide to go that way.

Whichever you decide on, you better come down and shoot that sucker.

I'm planning on it for sure. I just had a second surgery on my back (cervical fusion) with screws and rods. So while I'm down I want to build another to shoot. I guess my plan right now is to build a switch barrel in 7mm SAUM and .300 Win mag, give me a chance to play with both. I'll build it on a Surgeon LA most likely. Might just have Bugholes chamber me two barrels with the bugnut and call it a day!
What do you recommend for a twist rate for the 180's in 7mm?

[offgrid]

8.5 twist

I too am in the 7 camp. Just had a 2nd 7saum built on a short action, 30" barrel. Intended purpose ELR matches. Just started working up a load, up against 3000fps/180 Hybrids. Elrod chambered it.

1st 7saum a few years back, also on a short action. 2950/180 Hybrids 27" was the sweet spot with it. pulled the barrel with 1600rds.

Previous to that had a straight 284 on a long action. Shot the Sierra 175 SMK's, Berger 180 Hybrids just came out when I pulled the barrel at 2500rds. Depending how far you are going to shoot, the 284 is a sweet caliber. Very easy to tune, easy neck up Lapua 6.5x284 brass. Clearly see why the 284 is the darling of the 1000yd F-Class Open. It will drop anything at a realistic hunting distance.

[C Ward]

Look at the research Litz is doing about twist rates and BC , the old consensus of just use the bare minimum twist is been been pretty much disproven and there is a benefit to over stabilization especially at long range .

Buddy just finished his 7RM and is running the 180 ELDM and the twist is 7.5 ,IIRC , I'll have to check . The thing is a hammer and the 5 rds I shot out of it without adjusting it to me went in to about 2 1/2 inches at 640 yds prone with a bipod and bag . Just checked and the rifle is an 8 twist

He built the gun heavy with a 28" barrel on a Defiance action with 30 moa built in to the receiver , my first choice for actions now . Rifle weighs in at 20 - 21 lbs and recoils about like a 308 with no can on it .

With having a jacked up back a 7 will be easier to shoot , the 300 WM with 230 / 240 s has probably 30-40 % more recoil than a 7 with 180 s all else being equal .