Need Advice - 7mm Weatherby Magnum

BLC3128

Well-Known Member
Joined
Jul 1, 2017
Messages
109
Long story short. Well, not really so please bear with me!

I have a 1980s Mark V Deluxe. It’s my Whitetail, Black Bear and Backup Elk gun (600 yards and under on game)... The Throat/bore is excellent (26” w/ 1-10” twist).. I intended to work up some loads to match Weatherby advertised ammo (I’ll get to that towards the end). After some testing, My most accurate combo was 160gr Nosler Partition - MV 3235FPS (ES ~15). At 200 yards the best 5-shot-group was 1.15 MOA. Not bad for a gun guaranteed 1.5moa...

LOAD SPECS - Weatherby Brass Neck Sized , Fed 215 Primer, 160gr Nosler Partition, 78gr Retumbo, COAL 3.365” (I measure base to ogive, but don’t have that at the moment).

An issue I noticed was the cold bore shot was always way off. I even attempted to shoot, wait 30 minutes and shoot again and the groups were actually worse! My best sequence was to shoot, wait 5-7 minutes and shoot again. Doing this I would always shoot the cold bore “flyer” and then the groups would tighten up to around 1.15-1.25MOA. I was not happy with this and I decided to take the gun to RW Hart to have it pillar and glass bedded, trigger worked , and if needed a touch-up on the crown.

Back to reloading... I was using Retumbo as my charge, but noticed traces of unburnt powder in the bore after taking a shot. Is this powder too slow? Note - I did try h1000 but i didn’t like the accuracy...

Once I get the rifle back I will obviously be redoing my load development.. I do have several powders on hand: 4831SC,Norma MRP, RL25, H1000, and Retumbo. Also, I do have 160gr Nosler Partition and 160gr Accubonds on hand. Does anybody have any input/experience with these two bullets and some load data? If you have a pet load with a well constructed hunting bullet please share!

Closing remarks: Weatherby Ammo advertised ballistics. Their 160gr Nosler Partition Ammo is advertised @3200FPS. I took 5 shots each From 3 different boxes from 3 completely different lots and my velocity averaged 3080FPS with a 10fps ES!

Thanks,

Brandon
 
Last edited:

PoppaW

Member
Joined
Jan 9, 2018
Messages
24
Long story short. Well, not really so please bear with me!

I have a 1980s Mark V Deluxe. It’s my Whitetail, Black Bear and Backup Elk gun (600 yards and under on game)... The Throat/bore is excellent (26” w/ 1-10” twist).. I intended to work up some loads to match Weatherby advertised ammo (I’ll get to that towards the end). After some testing, My most accurate combo was 160gr Nosler Partition - MV 3235FPS (ES ~15). At 200 yards the best 5-shot-group was 1.15 MOA. Not bad for a gun guaranteed 1.5moa...

LOAD SPECS - Weatherby Brass Neck Sized , Fed 215 Primer, 160gr Nosler Partition, 78gr Retumbo, COAL 3.365” (I measure base to ogive, but don’t have that at the moment).

An issue I noticed was the cold bore shot was always way off. I even attempted to shoot, wait 30 minutes and shoot again and the groups were actually worse! My best sequence was to shoot, wait 5-7 minutes and shoot again. Doing this I would always shoot the cold bore “flyer” and then the groups would tighten up to around 1.15-1.25MOA. I was not happy with this and I decided to take the gun to RW Hart to have it pillar and glass bedded, trigger worked , and if needed a touch-up on the crown.

Back to reloading... I was using Retumbo as my charge, but noticed traces of unburnt powder in the bore after taking a shot. Is this powder too slow? Note - I did try h1000 but i didn’t like the accuracy...

Once I get the rifle back I will obviously be redoing my load development.. I do have several powders on hand: 4831SC,Norma MRP, RL25, H1000, and Retumbo. Also, I do have 160gr Nosler Partition and 160gr Accubonds on hand. Does anybody have any input/experience with these two bullets and some load data? If you have a pet load with a well constructed hunting bullet please share!

Closing remarks: Weatherby Ammo advertised ballistics. Their 160gr Nosler Partition Ammo is advertised @3200FPS. I took 5 shots each From 3 different boxes from 3 completely different lots and my velocity averaged 3080FPS with a 10fps ES!

Thanks,

Brandon
I have used RL25 with 150gr bullets. A light load right now is my best yet for this gun. My Deluxe is a 1973. I took the pressure point off the front as it seemed to give me occasional flyers. Also the rosewood forend was showing a stress crack inside. All good now and seems way more stable. My wife uses this gun exclusively and out shoots me on moose and deer regularly. I could always match factory speeds but had a hard time beating them. My 26” barrel always chronied on the faster side too. Hope your mods work as these are excellent guns.
 

Blackdirt Cowboy

Well-Known Member
Joined
Dec 9, 2018
Messages
478
Location
Texas
I was shooting the 160 grain factory ammo out o my weatherby before I started hand loading. I don’t believe their advertised velocities for a minute. When I started loading for this rifle, I started with the 160 grain bullets trying to match the advertised weatherby velocity. I couldn’t find a combination of bullet and powder that worked. I tried partitions, eld-x, lrx all with rl25, Retumbo, rl33, h1000, and nothing worked. So I dropped down to 150 grain swift sirrocos with the same results. Probably average 4-5” groups with all those loads.

Then I decided to drop down to the 140 class bullets. The first load I tried was the 140 grain accubonds. With the help of a good friend and his quickloads program, we decided to push it with rl26. Now the rifle shoots less than 1/2 moa pushing that 140 grain bullet 3400 FPS. My best group to date is .37 moa at 100 yards. I’m using Remington brass and federal 215m primers. I’m leery to give out charge weights, because you can’t control which numbskulls will see it in the future. But if this is a load that interests you, pm me. I’d be happy to share the quickloads data with you.
 

PoppaW

Member
Joined
Jan 9, 2018
Messages
24
I have never found reloader 26. Been looking a while. Thanks for the load offer but I think I found a match for this gun.
 

BLC3128

Well-Known Member
Joined
Jul 1, 2017
Messages
109
I was shooting the 160 grain factory ammo out o my weatherby before I started hand loading. I don’t believe their advertised velocities for a minute. When I started loading for this rifle, I started with the 160 grain bullets trying to match the advertised weatherby velocity. I couldn’t find a combination of bullet and powder that worked. I tried partitions, eld-x, lrx all with rl25, Retumbo, rl33, h1000, and nothing worked. So I dropped down to 150 grain swift sirrocos with the same results. Probably average 4-5” groups with all those loads.

Then I decided to drop down to the 140 class bullets. The first load I tried was the 140 grain accubonds. With the help of a good friend and his quickloads program, we decided to push it with rl26. Now the rifle shoots less than 1/2 moa pushing that 140 grain bullet 3400 FPS. My best group to date is .37 moa at 100 yards. I’m using Remington brass and federal 215m primers. I’m leery to give out charge weights, because you can’t control which numbskulls will see it in the future. But if this is a load that interests you, pm me. I’d be happy to share the quickloads data with you.

PM sent thanks again!

I was told by an older gentleman that often comes to the local gun shop that the 7mm Weatherby was designed to shoot the 140gr bullet. Makes sense and maybe that is why it comes with a 1-10” twist and from what I hear 1-12” twist in the earliest versions.

I’d like to keep this post going since there is not a lot of information about the cartridge to be found.
 

MarkA

Well-Known Member
Joined
Dec 12, 2005
Messages
328
Did lot of work trying to get better BC bullets to shoot in a 10 twist 7RM and had same issues. Just can't shoot bullets longer than 1.28-1.29 max lengths the twist is just not there. Had a load for slightly longer bullets but it fell apart in cold temps!

140 class bullets are about max overall. With 140 Accubond at 3,250 in the 10 twist 7RM using RL26 it is beast up to 600 yards at least. Very accurate and lethal combo for hunting. If you want long range you gonna need a barrel.

OR the best we tested was the 131 Hammer and can really run the speed up there with it. But lethal distance still pretty much the same as the 140 Accubond. Both are excellent bullets but the 131 Hammer was more accurate overall and easier to get load for but the 140 Accubond proved bit better BC at 500 yards.

Pick your poison.
 

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