Home Forums Hunting & Shooting Custom Rifles & Wildcats 7 Mashburn

That is how I ended up with the 120gr load I have, but of course the Mashburn (7mm/300 WinMag aka 7mm Practical in my case) outruns the WBY by a bunch at the end of the load development phase. I think that the case capacity on the 7/300WinMag is not far off from a 7mmSTW, so starting loads for that round might be an OK beginning place, too.

With the 4350 140gr. fire form load that it seams everyone uses, are they using mag primers or standard LR primers?
I loaded up 10 rounds the other day and after the fact I realized I used WLR. I know they will go bang I was just wondering from a accuracy stand point.

Les they will go bang and you will be fine.Never used them for the FF load (use Fed 215),but the WLR primer is no wimp.

The FF load does not shoot quite as "tight"for me in my rifle,as full house Mashburn,and it's slower than what the cartridge will do with a 139/140 but it's fine.Could hunt with it pretty easily.The 139 with 65 IMR4350 does 3150-3190 in my rifle.

I have only shot the 139 Hornady but Beretz used the 140 AB for app. 3200 with his FF load.

Thanks Bob.
I am hoping it tales a liking to a bunch of H1000 and a 150gr. Partition.

H1000 works with the 160's and 175's. That I know. Don't see that it should not work well with 150's too.

But you know how rifles are......

Les don't overlook imr7828 for the 150s

I have a jug of 7828, Retumbo, R22, and all varietys of 4831. 120 TTSX,120 BT, 150 PT, and 162 Amax. Keep the info flying.
And thank you all. I haven't even piped a primer in this rifle and I'm already loving it.

Les other than the FF load, I have not fed mine any bullet lighter than the 160's.

Seems the other guys will know about the lighter bullets.

Other than fireforming loads all I've ran is 150 grain ballistic tips and 160 grain accubonds both loads with IMR 7828. H1000 shot faster with 150s but wasn't as accurate as 7828

Me too. This combo works great in my 280's.

I have been working with H1000 primarily in mine. Does very well with both 160's and 175's. Retumbo would work just as well in mine but I didn't really have enough to work with. I get about 3050 from H1000 and 175 PTs, 3200 with 160's. Retumbo seems like it get another 50 FPS on those numbers.

Nice thing with the 7mm MSM is even those bulky powders like H1000 and Retumbo have PLENTY of room in the case to make it work well.

The 150 and 7828 sound pretty good.

140 AB and 65 grains of IMR4350 run 3225 from my fireforming loads. Around MOA. Could easily work with them, but heck, the accuracy on them is plenty for now and the speed is like a 280 Ackley +...

I have used RL-25 for my 160 gr. loads with fine accuracy +/- .5 in and 3275 fps. velocity. My 175 gr. load is 74 H1000 for 3075. I have some RL-33 to try with 175's but haven't had time to play at the range.

YMMV