7mm Sherman Short Mag

Given the relative unavailability of RL26, has anyone tried RL23? Both Magnum powders, RL23 and RL26 released at the same time. RL23 made by Bofors in Sweden, and RL26 by Nitrochemie in Switzerland. RL23 is advertised temp stable and RL26 as the higher velocity and somewhat less temp stable.
 
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I haven't tried RL23 but did snag 6lbs of RL26 from Powder Valley .

Loaded 59.6~60.2 in 2/10th increments. Wanted to go to 60.6gr but they've only been fire formed once so i didn't know if that was too stout. Here is next to dad's 6.5 SAUM.

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Update shot groups today. Hit pressure at 60.2gr but also some faint pressure at 60.0, let the gun rest and shot the rest of 60.0 without issue. Might pull 60.2gr because 59.8gr is absolutely hammering right now and right at 2900 (2892avg) 10.1 SD which is a little more than my liking but overall it's panning out about as well as i could've hoped. The pic below with the chrono is 59.6gr, the final pic is the one i shot of 60.2. I do hope it speeds up a tad but that 180gr ELD-M at 2900 is plenty. Been a while since i shot anything with a bit of a kick to it, damn thing kind hits hard like one of our light 308s lol

Have to say i had friends that had me a little worried about the Proof barrels but man this one is hammering.
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Update shot groups today. Hit pressure at 60.2gr but also some faint pressure at 60.0, let the gun rest and shot the rest of 60.0 without issue. Might pull 60.2gr because 59.8gr is absolutely hammering right now and right at 2900 (2892avg) 10.1 SD which is a little more than my liking but overall it's panning out about as well as i could've hoped. The pic below with the chrono is 59.6gr, the final pic is the one i shot of 60.2. I do hope it speeds up a tad but that 180gr ELD-M at 2900 is plenty. Been a while since i shot anything with a bit of a kick to it, damn thing kind hits hard like one of our light 308s lol

Have to say i had friends that had me a little worried about the Proof barrels but man this one is hammering.
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Any photos on neck area from fired case
 
Very interesting cartridge. Contemplating building a 7ss on either an Origin or TL3 for an elk trip this fall. What’s the rifle weigh with the 24inch proof 5RWill?

Right at 11lbs loaded with the bipod and can. But the proof makes a huge difference honestly. So dad's rifle is a TL3 6.5 SAUM, 3B spiral fluted @ 23", bedded in a MCS-T (carbon fiber), APA DBM, with a Zeiss V6 3-18. It's the same weight loaded with can and bipod, but doesn't balance as well because all the weight is past the midpoint due to the barrel. With the proof my gun despite the 3lb PRS2, heavier AMG, heavier 737R, and heavier can balances better and is actually a joy to carry. Granted i've been lugging around a 17~18lb comp rifle for the last couple of years. It still might be touch on the heavy side for an elk trip or mountain hunting for some but i don't think it would bother me. I've also never been out west but have been taking some huge strides as far fitness is concerned in the last year.

A TL3 bedded into a Manners 100% carbon fiber of your choice with DBM or floorplate, with a sendero lite, and an appropriately light scope would make for a hell of a setup carrying around and not being pencil thin. I also haven't really seen my proof "walk" like friends told me to expect after shots. They do heat up faster which is good because that means the fiber wrap is working. A string of shots through my 7SS and mirage is very notable and coming from both the barrel and can.

Speaking of which took my first deer of the season today with it. 378yds DRT 180gr ELD-M went through and through demolishing the heart and lungs. Recoil of this setup is so nice it's a wonder why anyone would want the huge magnums that some do out west. Don't get me wrong i get it ballistically speaking but as of right now a 180gr ELD-M at 2900fps with a little more felt recoil than a 6.5 SAUM is extremely pleasant to shoot. It is more recoil than i'm used to given the 17~18lb 6.5x47 i've been using for 4 years or so now. But i've been doing load development with our Sako 85 hunter in 260 with 123gr SSTs for Mom. Honest to God the thing hurts after a range session. Probably because the pad is hard as a rock but damn i don't know how i sat there and shot round after round 10 years ago when i got that rifle and first started reloading.
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Thanks for the reply and congrats on the harvest, very impressive shooting! I’ve never been out west hunting either but this cartridge seems to fit the bill. If you were to start the process over would you stick with a 24” barrel or go 26”? Also how did you settle on twist rate and were you able to find a gunsmith wth the 7ss reamer in their inventory?
 
Thanks for the reply and congrats on the harvest, very impressive shooting! I’ve never been out west hunting either but this cartridge seems to fit the bill. If you were to start the process over would you stick with a 24” barrel or go 26”? Also how did you settle on twist rate and were you able to find a gunsmith wth the 7ss reamer in their inventory?

So I’d probably stick with 24” regardless because i intend to hunt with a can and want the reduced length. Granted if you have a k config 30 cal can like the ultra 5 or something the 26” would be just as long as my 24” with the hybrid so it would balance out.

I originally had a 1in8 24” sendero lite but wanted to change to a sendero. Called gun ware where i got the proof and exchanged it for a 1in8.5. Which was the only sendero they had in stock but the owner assured me it would handle the 180gr eld m. Seems to be working. You’ll have to rent the reamer from Rich. At shermanwildcats.com
 
I had mine done at Patriot Valley Arms and LRI has done Shermans before. I believe Seekins Precision might be offering Sherman chamberings in the custom shop now too.
 
Went back out today took a big doe at 525yds with the 7SS. I couldn’t be more fond of this rifle. Incredibly accurate, pleasant to shoot, and most of all pretty light. Hit her right through part of the shoulder slightly behind through and through. She ran maybe 20yds. 2900fps with this particular round just caries some serious oomph. Kind of shocked it hit bone and still punched through.

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Wow! That’s some serious trauma, surprised she didn’t drop in her tracks. It’s amazing how tough white tails can be. Keep posting the harvest reports!
 
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Finally got the action; assembled the rifle last night, and was able to start some testing with RL23 today.

7 SAUM SAAMI Reamer
30" Kreiger 1:8 Barrel
183 SMK
Reloder 23
ADG Brass
CCI BR-2 Primers
CBTO 2.278"

I couldn't find any published data so just 5 rounds to establish baselines. No pressure signs. At 60.0g of RL23, thought I felt a slight crunch when seating the bullet - powder at the body/shoulder junction. The barrel is new, so I expect it'll pick up some speed. More to come.

Powder Load​
Velocity FPS​
58.0g2896
58.5g2929
59.0g2964
59.5g2996
60.0g3028
 
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To clarify for those looking for max speed, my 60.1gr load of H1000 works for me as a low pressure load with extreme low ES.

By comparison, I found in my setup H1000 was compressed at 61.6. Only the slightest freedom of powder at 61.4. I went up to 62.8 without pressure signs. Only using Area 419 funnel with out extension tube.
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180 ELDM load @ 2843fps (now)
60.1gr H1000
FGM210M
ADG Brass (fireformed)
26” Proof 1:8
Suppressed
BTO = 2.2090 (.02 off lands)
COAL 2.945


Not a speed demon but very consistent. Load from first pound had an ES 3-4fps
New pound of H1000 has ES of 7.

FYI - I find much better consistency when using one of the spare vertical spacers as a length spacer to get my Magnetospeed in the same spot on my suppressor. Too close to the muzzle of the suppressor, ES of same load was 73fps!!

For me, there isn’t much reason to fuss with extra powders to try for another 100fps but then again...
 
I'm contemplating the 7SS as my next build. Can 3k FPS be achievable with 180 class pills? I'm looking at a 26 in tube.


Yes it was designed around achieving just that with a 180gr hybrid. You’ll need RL26 but other than that yeah. The reason people aren’t hitting that with the eld m is likely because it has so much bearing surface.
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I'm contemplating the 7SS as my next build. Can 3k FPS be achievable with 180 class pills? I'm looking at a 26 in tube.
3000fps is certainly achievable but remember there is a difference between max velocity and accurate nodes. Lots of people like to quote their highest velocity like their lowest SD but max velocity nodes tend to be more finicky with temperature changes and especially with wet conditions. I almost got 3000fps with compressed H1000 loads (2930fps) but the ES wasn't as low which was more important to me.

There are many who get over 3000fps with this cartridge using shorter bearing surface bullets (Burger 180's) will get you there sooner than a long bearing surface like the Hornady 180 ELDM. Double base powdered are very useful in reaching 3000fps with N565 and RL26 being pretty successful. There are also barrels that tend to be slower or faster than others. Proof Barrels seems to go either way.
 
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Hey all,

I'm in the process of building a 7SS with a Bighorn TL3 and a 24" Proof 8T CF barrel. I'm very new to fireforming and want to make sure I get it correct. I intend to shoot 195 EOLs as the main hunting bullet, but I'm looking for some info on how to form the brass. I was planning to shoot a box of 140gr SMKs so I'm not eating the expensive stuff right off the bat. I could use some pointers on how to fire form. Any help is GREATLY appreciated. Thank you!
 
Beautiful looking rifle!! Great shooting. I’ve wanted an ss for a couple years now but there is zero support in Canada! Ideally I’d love to try a 270. Ss with the 170’s but can’t get brass
 
Yes. Because you are using a mild charge it doesn’t really matter how deep you jam the bullet into the lands, just that they are jammed. The idea to to make the brass pressure out. Jumping the bullet reduces initial pressure.
 
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I spoke with Rich on the phone yesterday looking for a couple recommendations. I was planning to push a 195 EOL at 2900-3000 from a 24" 1:8, he said I'd likely *touch* 2900 if I really stand on it but not much more. This threw a wrench in my plans since I was building this for LR Hunting with the 195 and needed that extra speed for the SG to be comfortably above 1.5 in my winter scenario. Since this barrel has not been cut yet, I'm looking at the 175 Elite Hunter as a possible backup. Does anyone have experience using this particular bullet?
 
I spoke with Rich on the phone yesterday looking for a couple recommendations. I was planning to push a 195 EOL at 2900-3000 from a 24" 1:8, he said I'd likely *touch* 2900 if I really stand on it but not much more. This threw a wrench in my plans since I was building this for LR Hunting with the 195 and needed that extra speed for the SG to be comfortably above 1.5 in my winter scenario. Since this barrel has not been cut yet, I'm looking at the 175 Elite Hunter as a possible backup. Does anyone have experience using this particular bullet?

Mine topped out with pressure at 2850 with the 195 eol but 60 grains of R26 and a 175 Hunter .020 off the lands gives me 3000fps, but mines a 26 inch
 
I spoke with Rich on the phone yesterday looking for a couple recommendations. I was planning to push a 195 EOL at 2900-3000 from a 24" 1:8, he said I'd likely *touch* 2900 if I really stand on it but not much more. This threw a wrench in my plans since I was building this for LR Hunting with the 195 and needed that extra speed for the SG to be comfortably above 1.5 in my winter scenario. Since this barrel has not been cut yet, I'm looking at the 175 Elite Hunter as a possible backup. Does anyone have experience using this particular bullet?
The 195 would reach 3000' in a 24" barrel with N570 but most other Good powders about 2925'
 
I spoke with Rich on the phone yesterday looking for a couple recommendations. I was planning to push a 195 EOL at 2900-3000 from a 24" 1:8, he said I'd likely *touch* 2900 if I really stand on it but not much more. This threw a wrench in my plans since I was building this for LR Hunting with the 195 and needed that extra speed for the SG to be comfortably above 1.5 in my winter scenario. Since this barrel has not been cut yet, I'm looking at the 175 Elite Hunter as a possible backup. Does anyone have experience using this particular bullet?
Yea, 2900 w/ a 195 is a tough ask. I shot 183 out of a 26" and had a hard time hitting 2900 (and es/SD at that speed was garbage). With the 175 I hit 3000 with good stats. That was with h1000 - would squeeze out more w/ RL26
 
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I just shot my second load with 60.5 of RL 26 and Berger 180 vldh with Rich's ADG brass. Threw it with my Intellidropper. Didn't even clean the brass... it is on its 4th firing.

3010 low to 3026 high. SD of 10.
No pressure signs. 26" barrel

I could only get 2970 out of H1000. And, at 3000 I was getting sticky bolt and pressure signs.

Pic was from my last outing zeroing the scope. I ran some at 60, 60.5 and 61 just to see how it went. Rich has his per load at 60.5, so I figured why not give it a tet first. 60.5 looks to be a keeper in this rifle.

I took it to Alaska last summer shooting the H1000. It did fantastic. I love this rifle and the 7SS.

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Im thinking of switching my plan of doing a 7 saum to a 7ss so I can run it out of a short action magazine, but am worried the case geometry wont cycle and feed smoothly from a magazine for hunting. It seems like there haven't been any problems from the game harvested in this thread but was hoping for some direct feedback before making a few purchases. Have any of you here had any problems with your 7ss cycling or has it been fine?
 
Im thinking of switching my plan of doing a 7 saum to a 7ss so I can run it out of a short action magazine, but am worried the case geometry wont cycle and feed smoothly from a magazine for hunting. It seems like there haven't been any problems from the game harvested in this thread but was hoping for some direct feedback before making a few purchases. Have any of you here had any problems with your 7ss cycling or has it been fine?

I use a standard SA accurate AICS wsm magazine in a DBM with a bighorn tl3 and have no feeding or ejection issues. I also have a 6.5SS on an impact action using the same magazines and have no feeding or ejection issues with that one either.

I will say the adg brass shows pressure differently that lapua and I start to see the brass get shiny around the primer pocket before other pressure signs but they are not much farther so stop when the brass shows any shinyness
 
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I’ve only got 2 firings on this brass but when I first got my 300 Sherman mag the only PRC brass available was Hornady and if I ran the Hornady where the brass got shiny around the pocket it would only make it 3 firings before I had to toss it due to loose primer pockets. The adg stuff seems to hold up better but need to push it a little more before I can answer with actual data
 
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A tikka will get you 3.4ish oal capacity in their longest magazine. They would definitely fit but you would have a lot of extra room on the magazine in front of the bullet. I dont know what effect that would have in feeding. I actually decided to get a custom reamer made for a 7 saum for a few reasons, but if I had a tikka with a ctr length mag or a manners mini chassis a 7ss is probably what I would have done instead so it could feed in a short mag.
 
A tikka will get you 3.4ish oal capacity in their longest magazine. They would definitely fit but you would have a lot of extra room on the magazine in front of the bullet. I dont know what effect that would have in feeding. I actually decided to get a custom reamer made for a 7 saum for a few reasons, but if I had a tikka with a ctr length mag or a manners mini chassis a 7ss is probably what I would have done instead so it could feed in a short mag.
Thanks for info. This would be built out in a non CTR, plastic DMB Tikka. So standard T3 mags. Of which there are a few diff lengths to be played with. Same with bolt stops. Might need to find someone who’s done a 7SS in a Tikka. I quite like the idea of a 180 @ 2950 in a short/med action rifle. Barrel at 24 gonna get you there?