nvbroncrider
Handloader
- Aug 20, 2011
- 3,085
- 4
7mm Mizzum
- Thread starter nvbroncrider
- Start date
joelkdouglas
Handloader
- Jun 5, 2011
- 1,310
- 3
Jake looks pretty good!
Thanks for sending the other dies. Once I get her up and running I am thinking of sending Lee a couple cases to make a Collet Die for her.
Thanks for sending the other dies. Once I get her up and running I am thinking of sending Lee a couple cases to make a Collet Die for her.
- Thread starter
- #4
nvbroncrider
Handloader
- Aug 20, 2011
- 3,085
- 4
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.
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.
Attachments
DrMike
Ballistician
- Nov 8, 2006
- 37,402
- 6,213
I used 175 grain TBBC and PT launched from my 7mm RM to take quite a number of elk (and moose). Those bullets were usually running somewhat slower than what you are generating, Jake. They seemed to drop elk quite smartly.
truck driver
Ammo Smith
- Mar 11, 2013
- 7,342
- 924
OK just what is a 7mm Mizzum? I wasn't around or missed the build post so I'm curious.
- Thread starter
- #11
nvbroncrider
Handloader
- Aug 20, 2011
- 3,085
- 4
Well got to do some work with RL26 and the 175PT.
68-2968
69-3013
70-3015
70.5-3035
71-3049
70 shot the best so played with seating depth from about 3.492" down to 3.460". 70 and 60 shot the best around 3/4" with 60 being 2 same hole one about .75" out. Might have a harmonic issue with the rifle as well. When I shot the 60 group first 2 were spread then 3&4 were 2" low right and 5 going in same hole as #1. I thought initially I pulled 3 so went loaded one and 4 went same spot so went loaded another and it went into the same hole as one.
Pretty fatigued at that point had shot around 35 rounds.
68-2968
69-3013
70-3015
70.5-3035
71-3049
70 shot the best so played with seating depth from about 3.492" down to 3.460". 70 and 60 shot the best around 3/4" with 60 being 2 same hole one about .75" out. Might have a harmonic issue with the rifle as well. When I shot the 60 group first 2 were spread then 3&4 were 2" low right and 5 going in same hole as #1. I thought initially I pulled 3 so went loaded one and 4 went same spot so went loaded another and it went into the same hole as one.
Pretty fatigued at that point had shot around 35 rounds.
Attachments
- Thread starter
- #12
nvbroncrider
Handloader
- Aug 20, 2011
- 3,085
- 4
I couldn't get things to repeat and we're getting worse so I pulled the rifle apart checked bedding swapped a 3rd scope onto it. Then started to work with another powder.
I went on to H1000 found a charge of 74 was shooting pretty good and then started adjusting seating depth it's coming around. Went another .005" shorter on the next and it opened considerable went back to the previous and it was the same as the first group. So what happened?
Well as near as I can tell I was using 175 2nds that were of two mixed lots. So when I seated the 3rd and measured it threw a flyer. It was .010" shorter than the other two in the group. So I measured all of my seconds to the Ogive in the ones I had remaining I had a difference of .012" so after I measured a box of 175's that were 1st runs and had .005" difference.
So all in all its shooting okay right about MOA but in my prior work with RL26 wonder if those double groups were caused by inconsistencies in the bullets/overall lengths.
I went on to H1000 found a charge of 74 was shooting pretty good and then started adjusting seating depth it's coming around. Went another .005" shorter on the next and it opened considerable went back to the previous and it was the same as the first group. So what happened?
Well as near as I can tell I was using 175 2nds that were of two mixed lots. So when I seated the 3rd and measured it threw a flyer. It was .010" shorter than the other two in the group. So I measured all of my seconds to the Ogive in the ones I had remaining I had a difference of .012" so after I measured a box of 175's that were 1st runs and had .005" difference.
So all in all its shooting okay right about MOA but in my prior work with RL26 wonder if those double groups were caused by inconsistencies in the bullets/overall lengths.
Attachments
- Thread starter
- #13
nvbroncrider
Handloader
- Aug 20, 2011
- 3,085
- 4
DrMike
Ballistician
- Nov 8, 2006
- 37,402
- 6,213
Lot-to-lot variations in components can be a killer, Jake. You likely did diagnose the cause of the flyers. That is pretty dramatic, but then your measurements indicate rather significant differences in OAL due to differing ogive, etc.
I'd be interested in seeing how the 175 gr loads shoot at 200-400 yards before I passed judgement on any of it.
Nvbroncrider have you tried any 160's yet?
To the guy who wanted to know what the 7mm Mizzum is, it was my nickname for the 7mm Mashburn Super magnum. a wildcat 7mm originally based on the 300 H&H,and developed by Oklahoma gunsmith, Art Mashburn back in the 1950's.
It was popularized back then by gun writer Warren Page who used it worldwide,and gun writer Bob Hagel who used it extensively over here on about everything.
Today it can still be made from 300 H&H brass, but is more easily formed with 300 Win Mag cases,which most of us use.
Nvbroncrider have you tried any 160's yet?
To the guy who wanted to know what the 7mm Mizzum is, it was my nickname for the 7mm Mashburn Super magnum. a wildcat 7mm originally based on the 300 H&H,and developed by Oklahoma gunsmith, Art Mashburn back in the 1950's.
It was popularized back then by gun writer Warren Page who used it worldwide,and gun writer Bob Hagel who used it extensively over here on about everything.
Today it can still be made from 300 H&H brass, but is more easily formed with 300 Win Mag cases,which most of us use.
- Thread starter
- #16
nvbroncrider
Handloader
- Aug 20, 2011
- 3,085
- 4
Shot one group @ 200 was around 3" I know I got some more work. But I think I was chasing my tail pretty good for a bit. Getting some weird stuff with the bullets I was shooting.
Jake,
I ran into the same thing when working with my 280AI. When I started load development with the 28Nosler I measured all my 175s before I began loading. I found about 10% out of spec. The other 90% were within .003" base to Ogive. My load is .065 off the lands so I don't think it matters a whole lot. The load ended up shooting .5moa all the way out 785 yds. Luckily I have enough components of the same lots for about 300rnds.
Scott
I ran into the same thing when working with my 280AI. When I started load development with the 28Nosler I measured all my 175s before I began loading. I found about 10% out of spec. The other 90% were within .003" base to Ogive. My load is .065 off the lands so I don't think it matters a whole lot. The load ended up shooting .5moa all the way out 785 yds. Luckily I have enough components of the same lots for about 300rnds.
Scott
