7mm SS vs 7 SAUM

[Willow]

This thread is more aimed at getting the opinion of anyone out there who may shoot, or have previously shot a 7mm Short Sherman (SS) compared to the proven 7 SAUM. I've never gone down the path of a magnum calibre but with many of the top shooters (at least in Australia), resorting to the likes of the 7 SAUM at major competitions, and at 'the longs', I'm seriously looking at magnum options. I've got plenty of friends who shoot SAUM's so I know what they are capable of but I am a fan of 'improved cartridges' and this looks to be a definite option with the 7 SS.

So why would I consider a 7 SS over a 7 SAUM? Well based on the opinions of others, and the reading I've done, is that it is essentially a more efficient designed SAUM, with a slightly shorter OAL, but a longer neck with a 40 degree shoulder, so it's been 'ackleyized' and has a slightly blown out sidewall, similar to a 284 Shehane. So velocity wise it will run with a SAUM but should require less trimming, and is made by ADG brass which from all reports is very uniform and strong. I know some users on hunting forums report better barrel life but that's not a major concern. The additional cost of brass/dies is not really a consideration for me given SAUM brass is expensive in Australia anyway, and ADG brass is yet to become available here so shooters stick with Norma.

If anyone out there has run a 7 SS or the Sherman Max which seems to be a direct improved version of the SAUM, was it easy to tune and keep in tune? I would only be using this calibre for F-Open with the idea of throwing the new Berger 190s down range. Any thoughts or comments welcome, even if it's based on the 30 cal versions.

 

[rardoin]

I know of two members who have shot this cartridge (or his own variant of the 7saum that is nearly identical to the SS) in LR F class. @cognac jack @ShootDots should chime in when available. I am waiting on a 7 SS reamer with a custom freebore to shoot 180-190 gr bullets; Rich’s standard reamers are .110 and .150 aimed for hunting loads. If this is an easy to tune case like the 7 saum with 180/184’s but can run a little faster with similar barrel life it would be a winner. In conversations with John and Ben they liked the cartridge but jumped over to the.300 WSM side of the street

 

[ShootDots]

I know of two members who have shot this cartridge (or his own variant of the 7saum that is nearly identical to the SS) in LR F class. @cognac jack @ShootDots should chime in when available. I am waiting on a 7 SS reamer with a custom freebore to shoot 180-190 gr bullets; Rich’s standard reamers are .110 and .150 aimed for hunting loads. If this is an easy to tune case like the 7 saum with 180/184’s but can run a little faster with similar barrel life it would be a winner. In conversations with John and Ben they liked the cartridge but jumped over to the.300 WSM side of the street

Good Mornin' Robin! I have not "changed over" to the .300WSM. What I have is 2 / .300WSMs and my 7mm Sherman Short. My first barrel in the 7SS loved the 184s pushed by H1000. But it would NOT shoot well 'til it hit 2990f.p.s. It shot very well there, however, the barrel burned out at 900 rounds. I love the cartridge, so I tried something to see if it would work. I went back to the 180 Hybrids and developed a GREAT load with 60.8grs of N165, which is about the coolest burning powder made. I am running right at 2905f.p.s. with low pressure. This should extend barrel life out several hundred more rounds. I have over 400 rounds on this barrel and there is STILL NO FIRECRACKING and the throat has eroded but a mere 2 thousandths! The reason I went to the Sherman is not for "velocity / performance". I went to the Sherman due to it's MUCH better case design! With very little case wall slope and a 40 degree shoulder, I almost NEVER have to trim and it shoots down to about .075-.125 @ 330 yards. The very first match I shot with this load was a 200-13X @ 1000 yards! I would say that it shoots pretty dang good!

 

[rardoin]

I was using N160 /180 Hybrids in my straight .284 and the throat erosion was stupid slow. Scoping the first 1/2 of the barrel at near 800rds showed almost no firecracking and the end of chamber/freebore junction was still sharp with no fire cutting. I was hoping that N165 could provide similar results in the SS when I get it running. I am also trying the 7 SS because of the very tight grouping I have witnessed with the 7 rsaum.

 

[cognac jack]

Hello, Well Robin was right, I designed a modified 7rsaum about the same time the 7ss was being designed and it was a winner. It is almost the same dimensions as the 7ss. The cartridge is easy to shoot and load for. Depending on the powder used it will extend the barrel life over the standard 7rsaum. Some of the powders used are more forgiving on throat erosion. Because of the case dimensions, I believe it is more accurate. I shoot the 184s and do not know how it will preform with the 190s. In my opinion the case is to small to push the 190s to the speed you need to over take the 184s in the wind. I shoot the 184s at 2920 fps. I am a firm believer that there is a correlation to the diameter of a case to its body length, which make its powder burning characteristics more consistent. Take the dasher, 7ss, and 300wsm cases and put then side by side and they look like the 6ppc and each other on steroids. Just my opinion. Hope this helps.
John

 

[whatwind?]

Why not go 7/270 wsm, use H1000 and should throw those 190’s out at 2900 no problem

35 degree shoulder

bertram makes brass in Australia?

 

[deepwater]

Norma & Nosler .270 wsm brass is available in Oz.

 

[rhovee]

What length barrel are you guys running that have the 7SS?

 

[Willow]

Why not go 7/270 wsm, use H1000 and should throw those 190’s out at 2900 no problem

35 degree shoulder

bertram makes brass in Australia?

I wouldn't use Bertram brass. Again thought, if I was going to go down that path I'd probably just get a Sherman Max made up which is basically an improved SAUM and will run those speeds with no issue.

 

[Willow]

Good Mornin' Robin! I have not "changed over" to the .300WSM. What I have is 2 / .300WSMs and my 7mm Sherman Short. My first barrel in the 7SS loved the 184s pushed by H1000. But it would NOT shoot well 'til it hit 2990f.p.s. It shot very well there, however, the barrel burned out at 900 rounds. I love the cartridge, so I tried something to see if it would work. I went back to the 180 Hybrids and developed a GREAT load with 60.8grs of N165, which is about the coolest burning powder made. I am running right at 2905f.p.s. with low pressure. This should extend barrel life out several hundred more rounds. I have over 400 rounds on this barrel and there is STILL NO FIRECRACKING and the throat has eroded but a mere 2 thousandths! The reason I went to the Sherman is not for "velocity / performance". I went to the Sherman due to it's MUCH better case design! With very little case wall slope and a 40 degree shoulder, I almost NEVER have to trim and it shoots down to about .075-.125 @ 330 yards. The very first match I shot with this load was a 200-13X @ 1000 yards! I would say that it shoots pretty dang good!

Hi Ben,

So riddle me this my friend, you've got a 7SS which was smoked after 900 rounds with a slow burning powder, plus a couple of 300 WSMs, which I've also done a bit of research on. Ballistically speaking, is there much of a difference between the two calibres? 2990fps with a 7mm 184 is smoking along in an F-Open rig. Is your 300 WSM ballistically better off at the longs with say a 215gr pill? There seems to be a consensus that the 300 WSM has a wide tuning window and is therefore quite easy to keep in tune. Have you found this to be the case? I would consider a 300 Sherman Max as it seems to be able to run at 300 WSM velocities according to the hunting crowd.

 

[Willow]

What length barrel are you guys running that have the 7SS?

I prefer to run 32" barrels, affords the ability to cut the barrel back a couple of inches for a re-chamber so you can go again for a bit.

 

[Willow]

Norma & Nosler .270 wsm brass is available in Oz.

Yes, but I'd prefer to run with a stronger, more consistent brass which ADG appears to be in comparison. There's no doubting the SAUM case is quite efficient and an improved version should result in being able to hold similar velocity at less pressure which is what I would prefer out of this move to a magnum calibre. I need to be mindful of speed due to energy limits in play at many ranges in Australia - most guys here are running SAUM's at 2910fps, so if I go down that path, that's the node I'm looking at, or probably the same speed if I went to a 30 cal.

 

[ShootDots]

Hi Ben,

So riddle me this my friend, you've got a 7SS which was smoked after 900 rounds with a slow burning powder, plus a couple of 300 WSMs, which I've also done a bit of research on. Ballistically speaking, is there much of a difference between the two calibres? 2990fps with a 7mm 184 is smoking along in an F-Open rig. Is your 300 WSM ballistically better off at the longs with say a 215gr pill? There seems to be a consensus that the 300 WSM has a wide tuning window and is therefore quite easy to keep in tune. Have you found this to be the case? I would consider a 300 Sherman Max as it seems to be able to run at 300 WSM velocities according to the hunting crowd.

The .300s have 2 bullets they shoot. One shoots the 230 Hybrids at 2775 and the other shoots the 200-20xs at 2900. The 230s shoot about 1m.o.a. inside the 7mmSS. The 200-20xs I can see no difference in wind drift between those and the Sherman. However, in BOTH cases, the heavier bullets do not exhibit as much vertical drift as the lighter 7mm bullet does. In my opinion, the .300WSMs, especially at 1000 yards, have an edge over most 7s (maybe the 195 Elite Hunter at 2885 is about the same) in both wind deflection and vertical dispersion. I have shot the 200-20Xs, the 215 Hybrids and now the 230 Hybrids. I have had about every 7 used in F-Open and those heavy 30 cal pills are definitely less effected by wind>>>no matter what the ballistic tables may indicate! Real world and math world are "worlds" apart. The .300WSMs are as easy or easier to tune than even a 6mm Dasher, of which I had 5! My .300 with the 230 Hybrids has a 7 tenths window! It does not get wider than that>>period. The .300s literally sit at the pinnacle of L/R F-Open in my "not so humble" opinion..

 

[ben_g]

My real world experience is similar to Ben’s.

I have seen less vertical dispersion with the 300WSM shooting 215’s than my SAUM shooting 180’s, I also believe the 30cal does shoot inside the 7mm, but it’s not by very much.

The 300WSM is also VERY easy to tune, mine shoots into 1/4” at 100yards over a 1.5 gr spread. I have found the SAUM also forgiving to tune with the 180hybrids, but has taken a lot of effort to find a sweet spot with the longer and higher BC 183gr Sierras.

I still use my SAUM where energy limits restrict the 30cal outside NSW.
But if I know conditions are going to chop up pull out the 300WSM every time for the longs.

Kris.
At last years NSW matchrifle state champs I shot on the same target as a bunch of 7mm cals in bad conditions. Beyond 1200 yards where the 7mm were just missing shots outside the 6ring (up down as well as side side) I managed to keep more just in.
It’s not a huge difference but I do think a big 30cal handles the longs better..... the issue is the shooter has to be able to handle the extra recoil.
I have just had a new 10twist Kreiger chambered by Matt to keep on shooting the 215’s, thinking I might try the 200Hybrids in it as well to use up some 2209

 

[Willow]

Appreciate the feedback thanks Ben and Ben (probably should nickname one of you Jerry). I'll keep saving some coin for now and continue to have a think about this.