The excellent 7mm Sherman Short Mag

[Winny94]

H4831 SC

Nodes at 59.5-60.5 and 62.5 grain.

What class of bullets are you running that with? The SAUM guys keep trying to steer me away from 4831, but as previously pointed out, the SS is a different case design, so maybe it would behave differently than they are seeing

 

[Winny94]

See if you can put your hands on some VV N565. It is a new powder and temp stable in the same burn rate range as H1000. It may be a shade faster burning. So start your load development about 1.3grs LESS than you would with H1000..

Thanks for the tip, I'll look into it

 

[Terry]

What class of bullets are you running that with? The SAUM guys keep trying to steer me away from 4831, but as previously pointed out, the SS is a different case design, so maybe it would behave differently than they are seeing

180's

 

[Rogmay]

See if you can put your hands on some VV N565. It is a new powder and temp stable in the same burn rate range as H1000. It may be a shade faster burning. So start your load development about 1.3grs LESS than you would with H1000..

ShootDots, what would your thoughts be on trying Retumbo in the 7SS?

 

[ShootDots]

ShootDots, what would your thoughts be on trying Retumbo in the 7SS?

I think that if you were going to shoot the 195s, it should be excellent! Whether or not it would shoot with the 180s / 184s or not would be a guess. Remember Retumbo is quite a bit slower than H1000.. It only cost about 30 bucks to get a pound of Retumbo>>>it definitely would be worth a try! I was quite surprised to see how well H1000 shoots! It is not that big of a leap to Retumbo!

 

[kvd]

Vihtavuori N165 may also be an option.

 

[ShootDots]

Vihtavuori N165 may also be an option.

I think N165 should work well>>>>now N565 should be right on the money..

 

[rhovee]

N565 isn’t a speed demon like N570 or N560 is. I have tried it in a few rifles and it’s right no top of H1000 with charge weight and speeds.

 

[Winny94]

I think N165 should work well>>>>now N565 should be right on the money..

The positive of 165 is it (as far as i can see) the coolest burning of all mentioned powders here. Now, is that the difference of 100 rounds or 600 rounds, I cant say.
Im assuming 165 is a bit temp sensitive? Otherwise it would be the go-to.

 

[ShootDots]

The positive of 165 is it (as far as i can see) the coolest burning of all mentioned powders here. Now, is that the difference of 100 rounds or 600 rounds, I cant say.
Im assuming 165 is a bit temp sensitive? Otherwise it would be the go-to.

The "Old" N165 was a little (not bad) temp sensitive. However, the "New" N165 is supposed to be very temp stable! And you are correct, it is one of, if not THEE coolest burning of the powders.

 

[Winny94]

The "Old" N165 was a little (not bad) temp sensitive. However, the "New" N165 is supposed to be very temp stable! And you are correct, it is one of, if not THEE coolest burning of the powders.

Do you have any insight on the difference b/w 565 and 165?

 

[ShootDots]

Do you have any insight on the difference b/w 565 and 165?

Yes.. N165 is a slight tad slower than IMR 7828 and is a single-based powder. N565 is a "double-based" powder, as in it contains a certain amount of Nitro in it's chemical make-up. ALL of Viht's "5 series", as in N540, N550, N560 etc.. all carry the nitro component and ALL are noticeably slower burning than their "1" series counterparts, as in N140, N150, N160 etc..etc.. So, N565 will be slower burning than N165 and it should produce noticeably higher velocities. However, at the same time, the 5 series, due to the nitro content, will eat up throats somewhat faster than their 1 series counterparts. I hope this somewhat long explanation helps.

 

[Winny94]

Yes.. N165 is a slight tad slower than IMR 7828 and is a single-based powder. N565 is a "double-based" powder, as in it contains a certain amount of Nitro in it's chemical make-up. ALL of Viht's "5 series", as in N540, N550, N560 etc.. all carry the nitro component and ALL are noticeably slower burning than their "1" series counterparts, as in N140, N150, N160 etc..etc.. So, N565 will be slower burning than N165 and it should produce noticeably higher velocities. However, at the same time, the 5 series, due to the nitro content will eat up throats somewhat faster than their 1 series counterparts. I hope this somewhat long explanation helps.

very helpful, thank-you.

Ive kicked the around the idea of having a hunting load that is pushed harder for more velocity w/ 175 bergers with H1000 or N565 and then a steel ringing load with something a bit cheaper like a 183 SMK and having a cooler burning powder for more extended strings would be nice, so that may be the bill for 165

 

[MrMajestic]

The "5" series and Alliant's Reloaders can produce some amazing velocities along with fantastic accuracy in the appropriate cartridges burnrates. I have never done a scientific evaluation but it is well documated as to the increased throat erosion by them. The intended discipline would dictate their use, i.e. competition vs. hunting and casual target/steel use.

 

[rardoin]

Back from the dead.

I now have 1417 rounds on the 7 Sherman Short mag. The first 300 (approx) rounds were with H1000 and the last 1100 with N165 and the Hornady 190 A-tips. I measured the throat at 100rds after FF'ing two boxes of cases. I retested seating depth at 600rds and found it shot slightly better 0.003" further toward the lands and opened up at 0.006" closer in. Good news in that the throat erosion was likely minimal compared to my .284. After having the gun start pitching vertical in the last LR match I remeasured the touch length and found it was only 0.012" longer than at 100 rounds; that is the erosion over 1300 rounds! I think I should have done another seating depth test prior to a 3 day match...my stupidity. I just cleaned the bore to bare metal and borescoped it. The firecracking looks like my .284/RL-23/184 hybrid/2800fps at 800rds and is minimal in the freebore and first inch or so of rifling (that explains the slow growth of touch length). It has moderate cracking from about 2-10" then nice and smooth after that. I was expecting about 1400 rounds of 'match quality' life from the barrel....maybe 1600 at best. I think I will exceed that. The reason I chose this cartridge was based on the design which, in theory, should have a longer throat life. John Farragio had discussed a near identical design with me at nats a couple of years back and suggested just going with the Sherman Short for ease of getting components. It was sage advice.

 

[Titan]

Back from the dead.

I now have 1417 rounds on the 7 Sherman Short mag. The first 300 (approx) rounds were with H1000 and the last 1100 with N165 and the Hornady 190 A-tips. I measured the throat at 100rds after FF'ing two boxes of cases. I retested seating depth at 600rds and found it shot slightly better 0.003" further toward the lands and opened up at 0.006" closer in. Good news in that the throat erosion was likely minimal compared to my .284. After having the gun start pitching vertical in the last LR match I remeasured the touch length and found it was only 0.012" longer than at 100 rounds; that is the erosion over 1300 rounds! I think I should have done another seating depth test prior to a 3 day match...my stupidity. I just cleaned the bore to bare metal and borescoped it. The firecracking looks like my .284/RL-23/184 hybrid/2800fps at 800rds and is minimal in the freebore and first inch or so of rifling (that explains the slow growth of touch length). It has moderate cracking from about 2-10" then nice and smooth after that. I was expecting about 1400 rounds of 'match quality' life from the barrel....maybe 1600 at best. I think I will exceed that. The reason I chose this cartridge was based on the design which, in theory, should have a longer throat life. John Farragio had discussed a near identical design with me at nats a couple of years back and suggested just going with the Sherman Short for ease of getting components. It was sage advice.

How fast are you running those 190s with h1000 and n165?

 

[rardoin]

That’s highly confidential information but it might be 2790-2800fps.....maybe.

 

[Titan]

That’s highly confidential information but it might be 2790-2800fps.....maybe.

I appreciate the top secret information . Out of curiosity why run a magnum with a 190 at a speed you could hit with a 284win/improved? Is the accuracy potential better than a 284 with slower powder and larger case capacity?

 

[rardoin]

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.

 

[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 primer were you using with the h1000 load thanks.