Is anyone running RL 26 in their 7mm MSM?

I've played around with it some.

Remington 700 KS Mag, chambered 7 Mashburn Super Mag
Right now a Pac Nor barrel
Trigger Tech trigger

It's notable for a couple things. First, it gives me good velocity with moderate powder charges. Usually a max 7 Rem Mag load will give max velocity for a 7 Weatherby.

Second, it gives me pressure signs really quick. Ejector marks, loose primer pockets, etc. If I try to get 3200 fps with a 160 Accubond the primer pockets only last 3 - 4 firings. It gave me pressure signs with the Remington barrel too; I figured a rebarrel would make it act like other Mashburns but no luck. Still, no elk is walking away.

Here's the rifle:


Load:
68.5 grains RL26 (max load for Alliant for a 7 Rem Mag and 150 SBT)
150 Scirocco II seated 0.10 off lands
Hornady brass
CCI250 primer
About 3175 fps

At 300 yards the other day:


This Mashburn is super finicky. Most others are not, i.e. Scotty's will give him 3250 fps with a 160 with no pressure signs.

I have with 150 ETips a bit and 175 Partitions as well.

Works about the same as 7828 and H1000 in my book, plus or minus 50 FPS in either bullet weight. Great powder for the case. I am using 33 for the 175’s right now though.

Gosh dang Joel, I hope you don’t mess with that load. Ain’t no reason to mess around there!

Thanks Scotty!

Also have a bunch of big events coming up. Glad to have a good load before Wyoming and Idaho this fall!

Changing brass brands could very well solve that problem. Same happened with my Borden 300 WSM. Mr. Borden suggested changing brass brands & test with the max charge in the Nosler book of the same powder that had locked the bolt up solid prior. I did & was absolutely shocked at the difference, immediately cured & those three shots went 1/2 moa.

Interesting you mentioned the 7 Wby. I cut my barrel back to 24” right out of the box. 160’s still go just over 3200.

Thanks ‘loder’!

I should have been more clear in my post too. It’s not RL26 specifically that’s giving me pressure signs, it’s the rifle in general. Other powers definitely give pressure signs. I could ignore the ejector marks and press on but the primer pockets are really the sign of too high pressure.

I’ve tried several kinds of brass, including Winchester, Nosler, Hornady, and RWS. I haven’t tried ADG yet. I have saved the rest of the RWS for the new Mashburn.

Even if the new Mashburn shows the same pressure signs I’m not concerned. I don’t expect more than 7 Weatherby velocity with the Mashburn. I would still pick the Mashburn over the Weatherby just because of readily available, good quality brass. Making the brass really isn’t much trouble.

I’ve tried it my 7 MB but found results no better or worse than with other powders. My rifle has done its best with H1000 and Retumbo, but I’ve had some interesting results with IMR 8133 that I’ll explore when the weather cools down. R26 isn’t the “magic fairy dust” like it seems to be in the 270 but can give nice results.
Like Joel, I start getting loose primer pockets at anything approaching 3200fps with 160gr bullets. And I’ve used every brand of brass out there. No problem, I prefer the 175gr bullets and I get a comfy 3000fps with those. Like Page, I like to stick with one bullet and for my uses I doubt anything will work any better than those.

Thanks. My results with the 160 were largely the same when I was working with the MSM in 2012. 3150 seemed to be about all I could get. I sold the rifle in a stupor and it has sat in a safe all these years unfired. I’ve traded back into it and it arrives Monday. Of course back in 2012 there was no RL26 so my experience is based on Retumbo, H1000, and 7828.

Danged nice rifle PF76! Holy smokes, I dig it.

I’ve ran a bunch of the same combos as you all. So far I’ve done well with just about all of the good slow burning powders along with RL33 and 175 Partitions. So far that’s my favorite combo. I change loads on a whim though cause well, I get bored and wanna see what else works.

Laughing, I’m the same!

That's a great looking rifle in the pictures. Who was the builder?

A gentleman in BC. I’m pretty sure he used the same reamer as the one you used for yours.

Interesting! I’ll bet it shoots pretty good with 175s.

It likes long bullets. :-)