Home Forums Reloading Big Game Rifles 7mm Mashburn and IMR7977

Sometimes they'll give you data not yet published.

May be worth a call.

DF

The Hodgen burn rate chart shows it right next to H1000 which is slower than RL25.

I think I like the 7977. It seams to be easy to work with. It took 2 rounds to find my 3200 fps mark. I loaded up 6 more and put those into a tight but wide 1.58" group.

I'm going to load up 6 more seated .015" deeper and see if it brings everything together.

My 168gr. Custom Comp and Retumbo load still lays them in there. That was a tough load to figure out. I seated the bullet .01" into the rifling and dumped enough Retumbo to hit 3200. Loaded up a few to shoot for accuracy and was done.
I dropped the first shot but was able to stack the next 5 shots into .38"

Les, what's the scoop on your barrel? Manufacturer, length, twist, profile, muzzle dia? I've got the reamer and the project is rising towards the top of the list. Trying to decide the particulars.

Gzig it is a Brux #4 , 1 in 9 twist. Muzzle dia is .70" @24.5"

Thanks for the info. I've got a Rem 7mag takeoff to play with to start but I don't how it will do with the 180+ bullets. Tossing around Brux, Krieger, and Bartlein. I know that they all make good ones so it's either a hard choice or a toss up. I shoot with a couple of guys that work at Krieger and have several of their barrels already so I'm leaning that way. Probably a little lighter profile though.

gzig: I would not go with a Rem takeoff for 180 gr bullets but then Ive never tried it so what do I know?

I'd go with a faster twist.

As to Kreiger contour this is a #2. 9 twist. Te rifle weighs a bit under 8 pounds as you see it. I think a #3 Krueger would be good unless you want SS....then you have to look elsewhere i think.





It will stay MOA or less at 500-600.





Les good info on 7977! Thanks for sharing that.

Bob,
I've already got the barrel and it was less than $35 for an unfired 26"er so I'm going to try it. If it only handles up to 168's that isn't the end of the world. I own the reamer so I don't mind playing a little and learning. I'm watching for a deal on a good #2 or #3 for the second pass. Going to contact Boots Obermyer and see if he has a 7mm coming in the future. Also have to decide between the post-64 M70 or the 700 BDL. Or maybe both.

gzig: Good approach......not much can't be done with a 160-168 I like the idea of burning up the cheap tube in round count and learning the cartridge.

Blow the farm on the second tube.

Either action will work but the Remington has the longer box as it comes so you can arrange bullet seating as you wish.

You can do the same with the M70 of course but it will need some minor modifications if it has a 30/06 box now.

The M70 is a PF 7mag with a 24" barrel. Bought with the Mashburn in mind, but the bore has a loose spot about 3" from the end. Shoots about 1 1/4" groups the little I've tried it, but not worth the wear on the reamer. The Mashburn should drop in, but I haven't looked at mag length.

Just like the 300 Win Mag, the Mashburn will fit in a 30/06 length box OR a H&H length with longer seating.

I like the long neck of the Mashburn so put it to use in a H&H box.

gzig: I didn't know you had 2 actions to work with. That makes things a lot easier. Take the Rem 700 and put together something like my Mashburn and cut the throat long like Bob does.
Standard fill McM #4 Brux fluted with steel rings and 10x SS comes in just under 10# and balances well.


Then take the M70 and cut the 3" bad spot off the barrel and chamber and throat the way I had mine cut. I wanted to be able to run light bullets really fast as well as heavies so I set a 120gr. TTSX up for .300 neck contact and added .05" That puts my 162gr. AMax at 2.88" to the lands. And 2.83" to the ogive on the 120 TTSX for .05" jump.

Well I loaded up some more IMR7977 and 160gr partitions seated .015 deeper than the first batch. With 5 shots going into .9" I don't really see a reason to burn up more components and barrel life.
In my book you can mark down 7977 as another great power for the Mashburn.

Nice work Les. Thanks for the thread.

Heard exactly what I needed to hear. Looks like another powder that hits desired velocity level and easy stuff to get my hands on as well.

Nice work that is a do all load. Man I'm ready get mine up and running

Laker; I thought you already had one up and bloody?

I couldn't resist playing with the partition some more. I still had 5 loaded up at 2.86" so I loaded up 4 each at 2.865" and 2.85". Hopefully I can get out in the morning. I'll take the best of that lot and bump the powder +.2 and -.2 take the best and be done.

Bob: I haven't found a powder and bullet that don't do well in the Mashburn. I always loved the .284 but was bored with the Rem 7. You said that the Mashburn was the best use of a .284 so I had Redneck put one together and I'll never look back.
The first trip out with some of Dober's fire forming load proved that I made the right choice.

Les it's always interesting to see how close a lot of these rifles are in terms of powder charges and velocities.

Of course there are differences because they are mostly custom; and I do see some differences when guys use button rifled barrels of some types....but it seems the cut rifle tubes are pretty similar. A couple of guys have seen sub par velocities but I suspect it's just a barrel issue since they aren't all created the same.

It was no accident that I used a Krueger for mine since I had so much prior experiences with Krueger barrels and the 7mm Rem Mag and Dakota, and knew what to expect.

For example I notice that your rifle and mine deliver similar velocities with the 162 Amax and 75-H1000; 75.5 gets me right to 3200 fps. I do not seem to be maxed out,although we are getting close. I recall Beretz ran QL on the Mashburn.....it seemed about in line with the 7mm Weatherby for pressures. In any event, I have never trashed a case for loose primer pockets nor had any traditional pressure "incidents".

Also much the same with Dober's FF load and 139-140 gr bullets and 65 4350. That's a stupid -easy load for anyone who just wants to size a few cases and go hunting as he FF's some loads. It's basically a 280 AI or 7 Rem Mag with room to spare.

Hell I'd build another one in a second. It's a piece of cake.

I've been following this thread with some interest.

I have a pound of 7977 on the way and I intend to load it in my 7mm Dakota, which as we know is the ballistic twin of the MSM.

Thanks for the load data all!