Is 7mm SST the perfect cartridge for me?

[MudRunner2005]

Thanks everyone for the replies so far, another follow-up question or two...

Why does it seem a few of you prefer the SS over the SST version? I probably don't need the faster feeding shoulder of the SST for a hunting rifle, but what are the downsides of it? Is there more velocity with the same powder charge from the SS version?

Also, let's say I decide not to build and instead go 6.5 PRC in a factory built rifle. Is there any real world difference I'll see on game in the 0-600 yard range?

The SS will have less body taper and a 40º shoulder. This means the SS will hold a little bit more powder, and the straighter walls and 40º shoulder will promote better pressurizing & pressure handling, resulting in more velocity. The 40º shoulder also helps keep brass from growing, which means rarely, if ever, needing to trim cases once initially fire-formed.

So, there are some advantages to the 40º shoulder over a 30º. Some will debate it's minute, and not worth the hassle or difference, but personally, I prefer 40º and very low wall taper cartridges.

Yes, there will be a huge difference in performance between the 7mm SS and a 6.5 PRC... The 7mm SS will toss a 180 grain bullet at nearly the same velocities as a 6.5 PRC with a 140-150 grain. Also, the 6.5mm bullet is .020" diameter thinner so it has less sectional density, and less expansion. I'm not hating on the PRC (this time), just pointing out factual differences.

Like was stated earlier, if you don't want to go wildcat, and you are not hellbent on a short action cartridge, the 7mm RemMag has a long-proven track record. With modern bullets and brass, and modern powders, it's quite an impressive cartridge, and still holds it own.

 

[FEENIX]

If you enjoy just having something a little different, then go for the 7 SS or SST. I find it hard to believe though that you'd ever see a real world difference on game or on target between a 7 SAUM, WSM, SS, SST or any other 7mm short mag when they're all built with the same components.

My only issue is with the 7mm for elk. If I were a deer hunter who might hunt elk every couple of years I'd feel pretty good with a 7mm and some quality bullets. If I'm looking for an elk rifle that I'll use on other critters it's .30 or larger every time. With a good muzzle brake, even something like a 338 short mag of some variety would be very manageable even in a 7.5# rifle.

Ditto!

 

[FEENIX]

Thanks everyone for the replies so far, another follow-up question or two...

Why does it seem a few of you prefer the SS over the SST version? I probably don't need the faster feeding shoulder of the SST for a hunting rifle, but what are the downsides of it? Is there more velocity with the same powder charge from the SS version?

Also, let's say I decide not to build and instead go 6.5 PRC in a factory built rifle. Is there any real world difference I'll see on game in the 0-600 yard range?

Welcome to LRH and enjoy!

It seems like you have a strong inclination on the SS/SST, if that is the case, go for it. Rich did an excellent job in his cartridge design. There is no need to complicate things or torture yourself unnecessarily. Go for it, it is not going to be your last build.

No, with the right bullet and shot placement, the game will not know the difference at <600 yards, dead is dead. Having said that, the .300 WM remains my go to chambering from antelope to elk size game up to 1k yards. Nothing fancy, it just plain old works. Load it 215 Berger and you're golden.

 

[yorke-1]

Thanks everyone for the replies so far, another follow-up question or two...

Why does it seem a few of you prefer the SS over the SST version? I probably don't need the faster feeding shoulder of the SST for a hunting rifle, but what are the downsides of it? Is there more velocity with the same powder charge from the SS version?

Also, let's say I decide not to build and instead go 6.5 PRC in a factory built rifle. Is there any real world difference I'll see on game in the 0-600 yard range?

I personally don't like 40° shoulders on mag fed chamberings in a push feed action unless the gun is using a centerfeed style magazine. They work fine but the feeding isn't very smooth in my experience. In a true controlled round feed like a Winchester, Ruger 77 or my current favorites, the Mausingfield and Nucleus actions, I haven't had an issue with them. I doubt that if you have two cases with identical capacity but one has a 40° shoulder and the other has a 30° and you loaded them to identical chamber pressures, you'd ever have a meaningful difference in velocity between the two. Case design can help hide the typical signs of case pressure like bolt lift or flattened primers, but that doesn't mean the pressure isn't there. That's why you sometimes see higher velocities from cases with sharper shoulders.

I don't think there's going to be a huge difference at 600 yards on game between a 6.5 PRC or one of the 7mm short mags. A good quality 140gr bullet in the 6.5 will kill an elk just as well as a good quality 180gr bullet from a 7mm with the same shot placement. There's a theoretical advantage for the 7mm but there's plenty of actual first hand data from folks using the 6.5 to prove that it's more than capable of killing elk at 600 yards.

 

[FEENIX]

I personally don't like 40° shoulders on mag fed chamberings in a push feed action unless the gun is using a centerfeed style magazine. They work fine but the feeding isn't very smooth in my experience. In a true controlled round feed like a Winchester, Ruger 77 or my current favorites, the Mausingfield and Nucleus actions, I haven't had an issue with them. I doubt that if you have two cases with identical capacity but one has a 40° shoulder and the other has a 30° and you loaded them to identical chamber pressures, you'd ever have a meaningful difference in velocity between the two. Case design can help hide the typical signs of case pressure like bolt lift or flattened primers, but that doesn't mean the pressure isn't there. That's why you sometimes see higher velocities from cases with sharper shoulders.

I don't think there's going to be a huge difference at 600 yards on game between a 6.5 PRC or one of the 7mm short mags. A good quality 140gr bullet in the 6.5 will kill an elk just as well as a good quality 180gr bullet from a 7mm with the same shot placement. There's a theoretical advantage for the 7mm but there's plenty of actual first hand data from folks using the 6.5 to prove that it's more than capable of killing elk at 600 yards.

Agreed! I am currently building a .264 WM with 26" 1:7" 5R primarily for the 140 and up bullets.

 

[hthunter]

300 WSM

 

[Josh P]

Are you dead set on a short action? If so a 7mmwsm or 300wsm are good choices as I'm sure the sst or ss are as well just don't know those cartridges. As to the 6.5 in a perfect world where every elk stands perfectly positioned for the textbook shot the 6.5 is capable. Now when that elk has you made and is standing head to you with a lot of shoulder between you and the vitals that 6.5 may not hold it together. Where a 7mm or 30cal have the bullet construction to break both shoulders and pass through. Now at longer ranges we have some time to wait for a better shot but 75 yards in the timber and you need to get through a shoulder bone crushing power is not over rated. I hut in steep country and try to break bone on bears and elk an animal able to move for 10 more minutes on a double lung shot may add a day to my pack. My timber rifle is a 338win shooting 250s in a lite 22inch barrel and if I know I'll be out in the open or possibly have some longer opportunity I run a 300wim with some 212eld.

 

[adam]

Lots of comments about technical stuff, that's all good... I love the technical stuff, and the 7ss seems like it would be totally up my ally....but..... launch dynamics in magnum calibers should be considered. I shoot 7mm 180 Berger's out of a magnum at 2950 FPS. Love love love it. I can dial a mile and stay supersonic.

Been around several similar calibers in 270 and 300. Heavy bullets at magnum speed require good form to shoot small groups. I have watched guys that are not recoil sensitive that swore their gun hated heavy bullets "proving" it with the tiny groups they shot when they dropped to medium weight bullets. Watching the whole process I could see the gun was shooting 1/4 moa, with every "mysterious " flyer at 12 o'clock. Happens to me too when I'm rusty.
Just my opinion, but if I were recoil sensitive I wouldn't want to burn big powder to shoot mid weight bullets in a cartridge that requires special brass. Special brass=loving time investment.... I'd rather shoot a 7mm rem mag with 162ish bullets at 3000+ than get a hot rod I can't run Hot. Both will get the job done, and if we are honest, most calibers in the same velocity range with similar weights are similarly effective.

For me magnum caliber choice boils down to those I can get quality brass for that fit in unmotified aics mags and run H1000 in volumes that allow it to be lit with 210m's.

 

[IndianaMatt]

Not sure what the sst is giving you over 270 wsm, 7wsm, 7saum for your application.

If it's the cool factor then yeah sounds perfect.

The Advantage of the Sherman will be COAL. It will function in a short action. The WSM stuff loaded with high BC bullets will not. I know you can argue with a Wyatt's that they will. You can also argue that a .284 Win will function. They will not. If loaded properly with the bullet not stuffed way down in the brass the WSM is to long using high BC bullets.

I like the OP really like the SST line. No fire forming, really good brass available, able to run effectively in a SA, and great support from Rich. I think it's a great compromise.