Home Forums Hunting & Shooting Custom Rifles & Wildcats The 7mm Mizzum

Kellywk:

Make the MSM. I use the COW method to final form brass; it doesn't waste bullets and expensive powder. Any pistol or shotgun powder will work. Bob has Quality brass and 40 should last quite a few hunts. For anything in the US, reformed .300 Win. is cheap and in endless supply.

As a disclaimer, I have 2 MSM's and one is a rechambered 7 Rem.

YMMV and my $.02 worth.

Docbill:

I've not fire formed before or had a wildcat before. Do you just run the 300 win brass through the full length die and load up a light charge with the cream of wheat and then bang away?

I'm leaning towards the rechambered 7 rem as they're pretty easy to find cheap around here

Kelly honestly you could go with any of the three. Long throat a 7 RM I think you'll get there. Plus /minus 3100 with a 160 should not be hard with todays powders.

The 7mm Weatherby is a slam dunk (I guess, never owned one). But reliable people on here get over 3100 routinely.

I'm happy with the Mashburn (which started out as something of an experiment) and like it a lot but the wildcat status and forming cases is a turn off for lots of people. Others are not bothered by it at all.

I bought the Quality Cartridge stuff but people on here gave me subtle hints about how good it was. I have not tried it so can't comment.

If head stamped brass is a concern, go Weatherby,7 RM etc etc.. But I know friends of mine hunting with Mashburns have taken rifles and cartridges into Mexico and Canada.I have not flown with mine yet, but am not really worried. Pay your money and pick your poison.


You could make life real simple and just get a 28 Nosler!

To COW form; form, prime, load with 20 +/- gr of just about any fast powder, toilet paper wad, COW, plug of canning wax, shoot.

Bob has a hunting fire form load with 140 gr that is accurate if you use bullets that light for deer hunting. One thing you will need to do is anneal the necks on the cases after about 4 loadings. If you will do this, it will last almost forever. I use 7 Roy load data. It has a pretty good margin of safety since the MSM has more case capacity.

I much prefer MSM to any of the others and I don't have a 28 Nosler.

Doc is less reluctant to recommend the wildcat than I am. ...but we both like it best.

It isn't hard to do. below are COW formed Mahburn cases, recently made.

Recipe for COW: CCI large pistol primer.13 gr Alliant Bullseye. Fill to base of neck with RCBS dried corn husk tumbling media. Top off with a wad of tissue.

OR

Form and charge with 65-IMR4350-139 Hornady (or some other favorite 140 gr bullet works for other folks). This is a below max pressure load that is no toy and will show 3150 fps or so. You could easily hunt with this stuff.

Just for information, I make all my 7 mm Wea. Brass out of 7 mm Rem cases. One pass through the Wea die and my brass is formed, and a bit short so no trimming needed for a while. My Wea is on 700 action so I am able to seat a 160 flush with the bottom of the neck. Last time I checked I was getting about 3250fps with the 160's. Solves the issue of getting Wea brass.

Still the Mashburn has much to recommend it. Probably if I were going to make a new big 7 to day, I would give the Mashburn a close look. Have considered rechambering my old 7 mm Rem to the Mashburn case. It is 1200 plus rounds old, that might give me a "new", rifle without a rebarrel job. The only thing is this old 7 was my late wife,s favorite big game rifle,and I am pretty much a .30 caliber guy.

7mm mashburn is one of the easiest wildcats I've ever messed with. I've been running 300 win mag into my mashburn FL die and been working fine vs using the form and trim die. I say go for it

Same here, I borrowed my first set of 7mm MSM dies from another fellow MSM shooter while I was waiting on my dies from Midway. Once I got the new ones, I simply forwarded them back to my buddy and kept his old ones since I have them all set up for my rifle.

I was a little hesitant to do all that fireforming but honestly, I can't hurt the first 50 cases I formed a year ago. I anneal them regularly and they just last. I have ran 65 grains of IMR4350 with 140 Accubonds, 139 Hornady SPBT's, 140 BT's, 145 Speers, 140 Sierra's and probably some others I have forgotten. All of them net around 3150-3200. This last time I used some IMR4451 to do my forming since it was supposed to be a little cleaner, but it was only around 2980 or so.. No big deal either way, the cases come out perfect.

I will say when I started with MSM, Bob and another said get some H1000. I did and followed their lead. Took all of about 24 rounds to get me a load with the 160 AB and the speed they said (3200). My only problem was all I could get were 1 pounders back then. A couple of them were from the same lot, but I ended up with 75.5 with the 160 AB's (3200) and 73 for the 175's (3050).. Well, I was finally able to get a fresh 8 pounder of H1000.. Quite alot slower than my older 1 pound containers as 73 grains with a 175 PT only netted me about 2890.. Not a big deal, I'll just keep adding coal to get it up to 3050 again and I'll have that load for a long time I bet.

I like the cartridge so much because of the ability to run a lighter rifle and maintain some excellent reach. Blasted a poor cow this past fast in Wyoming and it just stunned her at 250 yards with the 160 AB. Blew on through and she lifted her head up once and was done.. Nothing special and I am sure elk hunters have seen it a million times, but is nice to have a 0-500 yard rifle without having to think of much of anything.

Mines just an old beat up 70 XTR that a great friend let me borrow a reamer for. That rifle has turned out some EXCELLENT groups for me on the factory barrel. I have liked the cartridge so much, I am pretty sure when I can put aside some loot, I'd like to have a nicer one made up. Till then, I'll keep slumming this old, ugly Model 70..

Another nice part, that I think Doc Bill mentioned was being able to use 7mm Wby data to work up with. I recently tried that with some 150 ETip's. It works, you don't have to stone wall the MSM to get Weatherby speeds at all.

Just my take on it so far, but I hardly ever go to the range without it honestly. I have a harder time picking a bullet I wanna run out of it than anything else..

Great post Scotty!

Yeah the FF in mine are running 3100 with WLR primers. Shot a .5" 3 shot group with 140 BT's I can't complain.

Anyone know what kind of velocity Dober was getting with 7828 and 160's?

Not Dober but I used his data and I was getting 3200 with 160 grain accubond

nv: You can just hunt with that load!

Yeah I could Bob but I'd only have one shot. It's a little on the stiff side to chamber the 2nd for a quick follow up!!!!

Perfect. I'll have to try it. Was that Max in your rifle? And yours is a 24" tube correct?

Yes a 24" tube. I wasn't flattening primers or anything but I figured 3200 with a 160 was enough. Never pushed it any harder

Just wondering if you pushed it up to see pressure so I had an idea. Start at 68 and should be good. How was the accuracy?

Have you tried 168 ABLR or 175 PT?

nv:With the old stand by single base propellants like 7828,H4831,even H 1000, you are going to see something like 3050-3075 from a 175 gr bullet. Powders like RETUMBO,and RL25 will show a bit more.

With those two powders a 160 will show up to 3250 with no concerns in any 24" barrel I have seen used

I don't like to see any more than a hair under 3100 with the 175; nor more than 3250 with the 160 from the case and 24" barrel, regardless of powder, although longer barrels will show more speed.

I think those parameters were designed into the cartridge 50+ years ago and create a very potent open country BG cartridge.

You should be good to start at 68 grains. I only ran 160 grain accubonds and 150 grain ballistic tips. Both very accurate. I just stuck with the 150 grain ballistic Tips because I was shooting to much and the accubonds got to expensive to bang steal with

3050 is what I'm hoping for just was trying to see if I need to get a jug of H1000 or if anyone had any data on 7828. 3200 with a 160 is plenty just trying to get some ballpark numbers as a start. Got some cases ready to load.

I know yourself and others have said 7Bee data is safe but just trying to do a little extra due diligence.