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

Absolutely a good idea.

Just offering observations based on what we have seen first hand from the cartridge with different powders.

It's still a wildcat,so we are on our own.......Knowing I could push it faster, I have always tried to stay on the conservative side and have still been impressed with how "easy" and tractable it is to load.

Be careful with the 7mm Weatherby data....I know first hand the RETUMBO data with 160's is very hot if you approach MAX in the Nosler manual. The 7mm Weatherby seems to be loaded pretty hot. I would work up to any 7mm Weatherby data in the Mashburn from below, to be safe.

Well hello Bob. Been a while sense I grazed the pages of the campfire and first thing I see is Mashburn. I need to break mine out of the safe and burn some powder.

Les: How are you!

Seems some other guys have climbed in and built Mashburns, so the discussions continue.

Break yours out and do some shooting!

Agree with this. I know when most folks ask me about data for the MSM, I usually direct them at published WBY data as a starter. Bob nailed it by saying start at the bottom. You'll see straight away with your chrono where you stand. It's about the closest thing we have for published data if you want a baseline.

Jake, I'm looking forward to your work with 7828 and the 150-175 class Bullets. Seems like any of them will really do excellent in the MSM.

Yeah. This ain't my first rodeo with a wildcat. Got a 338-06AI 6-284 then a bunch of old cartridges that in a good modern action can be pushed a bit harder than the 45-55k they were approved at back in the day and that factory rounds are loaded at. Seems like you guys have got it figured out so it will help me get there a bit quicker. The 338-06AI was an adventure since there isn't as much info out there on it. The 6-284 was as well. I did pop a primer on the 6-284 first time seeing that don't want to repeat it for dang sure. Learned a lot from those two. With as much info as there is here on the Mizzum I hope to not repeat any of the lessons I previously learned.

Hopefully I can post some results Thursday or Friday.

Jake

Jake: I'm not long on experience with wildcats, the Mashburn being my second one.

You will gobble it up. It's an easy wildcat.

For anyone looking to build a Mashburn, I have a reamer that could be loaned out. If I like you and approve of the smith that will be using it.
I recommend Redneck.

Here is my baby in some Rhino camo

Sweet rifle Les... I'd put a picture of Ol Ugly but it'd hurt your eyes!

Hey beretzs, I've seen old ugly. The only way that would hurt my eyes is if I got to close to the scope. Pain would go away when I seen the group though

Good point. It is hard for me to abandon it just yet, it is still shooting well..

Today got some shooting in with it. Running 175PT with 7828SSC. 66-2958 67-2995 68-3049 69-3111 too hot. Really stunk when I loaded 69-71 and had to pull everything I loaded and start over.

Shot groups at 67 67.5 and 68

67 was a start had no clue went about 1.5" 67.5" went 1" 2-1 68 opened way up and the last in the group showed just a hair of pressure. These were all loaded @ 3.480"

Went back to the bench loaded some more 3.470" went under 3/4" and 3.460" opened up in a pattern 1 right 2 left 1 right.

Will shoot 3.470" and play down to 3.465" hopefully she'll suck them in. A 175PT @ 3020-3030 should be good elk medicine.

Sounds like you're there with 7828. I'd play with seating and shoot it to 300 yds plus next.

Thing I love about the Mashburn is that even lolly gagging with starting loads you're right there with top end 7 mag loads. No mysteries about "where'd my velocities go?" LOL

Looking good. You analyze this chit the way it needs to be done. Something a lot of guys can't do. What part of NV?

North central. Between Winnemucca and Elko

Sounds like the Battle Mountain area. I grew up in Winnemucca... A lot of jack rabbit slaying got done when I lived there... . Your 7 will work on those too... They make excellent offhand target practice...

I made another 100 pieces of Mashburn brass yesterday. I thought I'd post the process for those who've never done any case forming and are a bit intimidated. It's really straightforward.

The series of pictures with the COW (cream of wheat) loading are actually 7mm RUM brass that were necked down from .300 RUM, but the process is the same.



First, run .300 Winchester Magnum brass through the 7mm Mashburn Super sizing die. I found that the only real part of the case that gets any sizing is the shoulder and neck so I simply get lube on my thumb and forefinger and coat the neck and shoulder slightly before running it though the die. Lube the inside case neck too...

These are actually 7 MSM brass and their parent, the .300 WM



The little ring you see toward the neck/shoulder junction is where I stopped neck turning when the brass were originally .300 WM. After forming, I re-turned the brass to the new neck/shoulder junction and even into the shoulder a tad to eliminate any donut situation. This is the final product:






After sizing, I prime, load 20 grains of fast-burning powder (not critical. Unique, Red Dot, etc..) and fill with COW (I use coarse Polenta ) to the shoulder area...





When I did these, I filled them too full into the neck. Just shake some out to allow for the next step...


Melt some paraffin wax in a double boiler and use some sort of eye dropper to dispense it into the case to the top of the case mouth...












At this point when the wax has cured, go out and chamber shells and pull the trigger to form. The batch I just got done forming was pretty much fully formed in length anyway.







Simply decap, tumble, size and load....

Nice post Rick. Well organized as I'd expect and easy to understand.....

Thanks!

Tag

Rick does the polenta smell good when you torch it off?