The excellent 7mm Sherman Short Mag

[ShootDots]

Good day, what primer were you using with the h1000 load thanks.

CCI BR-2s....

 

[kev77]

CCI BR-2s....

Thanks very much

 

[Titan]

I’ve tried the long/heavy 7’s in my .284. I could not get the vertical out of the loads at 600/1000yds. I suspect they like a slower burning powder. The magnum case has the capacity for such powders....no go in a .284.

Interesting thanks for sharing.

 

[Sniper338]

This round has been on my list for a few years. I just haven't done it. I've gone towards smaller rounds lately. It is excellent reading material to read up on the Sherman line though...

 

[rardoin]

I have found it to be very easy to load for. I'll repost a 100yd crude charge weight test covering 3.6gr of N165/190 Atip after doing a 0.010" increment seat depth test at 57.5gr. Amazing that the group center changes so little relative to the point of aim. I held it to 100yds because the winds were about 8mph at a high value angle and gusty.

 

[gman47564]

I have found it to be very easy to load for. I'll repost a 100yd crude charge weight test covering 3.6gr of N165/190 Atip after doing a 0.010" increment seat depth test at 57.5gr. Amazing that the group center changes so little relative to the point of aim. I held it to 100yds because the winds were about 8mph at a high value angle and gusty.

View attachment 1208173

robin you forgot to shoot the other two at 58.4...

 

[jsthntn247]

I have found it to be very easy to load for. I'll repost a 100yd crude charge weight test covering 3.6gr of N165/190 Atip

after doing a 0.010" increment seat depth test at 57.5gr. Amazing that the group center changes so little relative to the point of aim. I held it to 100yds because the winds were about 8mph at a high value angle and gusty.



View attachment 1208173

What kind of velocity are you getting on the upper end at 60?

 

[rardoin]

2800fps at 60.0

 

[kev77]

Late last year I decided to move away from "small" calibers, i.e. 6MMs and 6.5MMs, in favor of the .300 W.S.M. So far the decision to go that route has paid off handsomely! However, a friend of mine, John Farraggio, a.k.a. "Cognac Jack" on here, told me about a cartridge I had never heard of, The 7mm Sherman Short Magnum. After looking at the cartridge and speaking with Rich Sherman, I decided to give it a try.. My goal was to shoot the 184 Hybrids somewhere above 2900f.p.s. I like 7mm ballistics, however, the 7mm always seemed to me to be a P.I.T.A. to get tuned properly and KEEP it tuned properly. I am not a ballistician so I never could figure why I was having trouble. However, after looking at the Sherman case, it looked exactly like a 6mm Dasher on steroids! I thought "well this may be the answer to my issue"! I called Rich to get the "particulars" on his creation. I can't remember the exact dimensions but I can give you a pretty close approximation to what it is: a 7mm S.A.U.M. case shortened by 90 thousandths, the neck shortened from the forming BUT still, I believe, 40 thousandths LONGER than the standard S.A.U.M. neck. Then it is "Acklyized" with a 40 degree shoulder, however, with a somewhat "straighter case wall".. The end result is that for the shooter shooting steel or hunting, it is what the S.A.U.M. should have been!

So I decided to build one. Components: Defiance "Deviant" short action and melonited. McMillan "Kestros" stock with adjustable cheek piece and 3 way butt metal. Also that BIG 1.5" "Nitro" pad. An "old" Kelbly trigger and a Krieger 1-8.5 5R barrel and a Kahles 10-50 with the MOAK reticle. ADDITIONALLY: It should be known that this IS a proprietary cartridge and EVERYTHING has to be bought thru Rich. I got a Whidden bushing die, Forster "Ultra" competition seating die, a JGS reamer to MY specs (Rich worked with me on this one), and 7 Sherman brass ALREADY MADE UP from A.D.G. All you have to do is fireform it like any other fireforming operation.

Long story short, I got everything assembled and AFTER fireforming, I tried powders that I thought would work. H4350: I could NOT get it past 2880f.p.s without a stiff bolt lift! Why? I don't know.. H4831sc. Okay NOW we are getting somewhere. I could reach 2950 without a bolt lift issue. At 2910 it was shooting excellently at 300 meters. I took it out to a 2 man team match at 1000 yards and got A LOT of vertical. Back to the drawing board! Let's see, RL-23 is within the burn rate range of H4831sc, let's give that a try. The velocity was certainly there, however, the accuracy was not. I thought "Here we go again, with trouble tuning yet another 7mm". I called Rich and found out that this particular case L-O-V-E-S slow powders. Ok let's try H1000. Well all of a sudden this case turned on! I could easily get well in excess of 3000f.p.s with ZERO pressure signs! From 60.7grs to 61.3grs it shot almost identical groups in exactly the same location on the target at 300 meters! WHOA! Now this is a W-I-D-E window. I said "Ok, let's settle on 60.9 and take it to a match to see about vertical". Yesterday, Sunday, we had a 60 shot 600 yard match at Ben Avery. Winds were from about 7m.p.h. in the morning to 15 or so in the afternoon. The vertical was FLAT AS A PANCAKE! NO "where did that come from" vertical! The velocity is running from 2945 to 2954f.p.s. The accuracy at 300 meters hovers in the vicinity of 0.75-1.00 inch. This is for 3 / 5 shot groups I tested. Now that I know this case desires slow powders, I believe it to be an excellent 7mm to use for F-Open and Steel, for those into that game! It also should be easy to tune from hitherto forth!

Good day, what is the case capacity of the 7 SS and the 284 shehane. ? Thanks

 

[ShootDots]

Good day, what is the case capacity of the 7 SS and the 284 shehane. ? Thanks

Rich told me what water capacity was, however I forgot it. But if memory serves me, it was somewhere in the vicinity of 66.0-70.0grs of water. I don't know what the Shehane is>>>>but it is supposed to be right at 3grs more than a "straight" .284. However, in real (not water but powder) weight, you get about 1.1 to maybe 1.3grs more of powder in a Shehane over a .284..

 

[rardoin]

The 7ss is about 71-72gr h2o IIRC.

 

[F Class John]

Real world so far for me had 62 grains of H1000 in the Sherman with a 180 hybrid over it and no compression and not even close to compression. With 190 A-tips (longest bullets I’ve ever used) I had them over 60.4 grains of H1000 with them just barely touching powder but that was with only .250 freebore instead of something like .300 to .325 which is what the a-tips really need.
With a faster powder like N165 or RL23 you would have even more room.

 

[rardoin]

For reference, 60gr of N165 will fill the case to the lower 1/3 of the shoulder where 60gr of H1000 is about 1/2 way up the shoulder.

 

[tom]

Bump for @urbanrifleman this might be what your after for a 7mm.

@ShootDots any updates?

Tom

 

[ShootDots]

Bump for @urbanrifleman this might be what your after for a 7mm.

@ShootDots any updates?

Tom

No news.. It is just an excellent cartridge. It will easily reach the 2900+ node with either the 180 or 184 hybrid bullet.

 

[tom]

Thanks Ben. On another thread urbanrifleman was seeking out something similar, so I thought I'd bump this one up.


Tom

 

[Tater83]

I have found it to be very easy to load for. I'll repost a 100yd crude charge weight test covering 3.6gr of N165/190 Atip after doing a 0.010" increment seat depth test at 57.5gr. Amazing that the group center changes so little relative to the point of aim. I held it to 100yds because the winds were about 8mph at a high value angle and gusty.

View attachment 1208173

Impressive groups. Im new to the sherman shortmag. Having one built now. Have you used the 190 atip hunting at all and if so how did it perform?

 

[rardoin]

Impressive groups. Im new to the sherman shortmag. Having one built now. Have you used the 190 atip hunting at all and if so how did it perform?

I have not used it for hunting. I built the 7SS as a dedicated target rifle.