338-378 WBY Mag

[Ironworker]

I have a Weatherby Mk V accumark in 338-378 . I hand load for it,trying to develop a load for it. I'll use it for long distance steel shooting. Bought used for a once in a life time price. Highly doubt I'll ever go to Alaska for bear and moose. . Anyhow I'm wondering what I can expect for accuracy in this rifle and then live with it. Shooting it standing up isn't bad but off the bench is a different story.( Its a beast) I bought a Terminator T4 muzzle brake and its amazing how much recoil reduction there is,but the muzzle blast its also another story.

 

[Sam7sf]

Only one way to find out.

 

[HKShooter65]

Welcome to a great gun web site.

I like the extremes.
Tiny .17s and big bores.

Your 338-378 reloading sounds like a great project.
Was once invited to shoot a Mark V 378 from a bench.
Shot it.
Just once we enough!!!

Keep us informed.
Oh, and there is a whole category here devoted to reloading with lots of wisdom to be had for free.

 

[benenglish]

Welcome to the site.

Shooting it standing up isn't bad but off the bench is a different story.

I've got a 5-pound .340 Wby. I won't shoot it from the bench; it's standing only.

 

[Ironworker]

Thanks everyone .I've installed a Ken Farrell Industries scope rail designed for this particular big boomer. Directions say re- tighten screws after first few shooting sessions,I did notice after zeroing rifle all of a sudden entire next group would be off ! So I removed scope and sure enough needed tightening. Directions said that's the scope base settling Other forums are saying I should put lock tight on all scope mounting screws .( but when,should I let the base settle some more?) Bought the rifle used under 40 rounds thru it. Already had a scope with leupold standard rings 30 rounds later scope wiggled like jello . I have that Terminator T4 brake on it,but after 20 rounds dang it that rifle is still a beast. Like all of you I love guns and reloading my own ammo. But I kinda wish I saved my cash and bought a 6.5 PRC. Its easier to buy a rifle than sell it. This rifle came with 5 boxes of brass,some new, rcbs dies Leupold 3.5-10 scope which I sold and 2 lbs of Retumbo powder.

 

[FireInTheWire]

https://www.capitolarmory.com/silencerco-harvester-big-bore-338-suppressor.html

https://www.amazon.com/Beartooth-Re...l+pad&qid=1549855348&s=sporting-goods&sr=1-11

These 2 items made my 338LM a pussy cat. I highly recommend. Those big bores are no fun without a suppressor. The recoil pad is the icing on the cake.

.02

 

[FireInTheWire]

Thanks everyone .I've installed a Ken Farrell Industries scope rail designed for this particular big boomer. Directions say re- tighten screws after first few shooting sessions,I did notice after zeroing rifle all of a sudden entire next group would be off ! So I removed scope and sure enough needed tightening. Directions said that's the scope base settling Other forums are saying I should put lock tight on all scope mounting screws .( but when,should I let the base settle some more?) Bought the rifle used under 40 rounds thru it. Already had a scope with leupold standard rings 30 rounds later scope wiggled like jello . I have that Terminator T4 brake on it,but after 20 rounds dang it that rifle is still a beast. Like all of you I love guns and reloading my own ammo. But I kinda wish I saved my cash and bought a 6.5 PRC. Its easier to buy a rifle than sell it. This rifle came with 5 boxes of brass,some new, rcbs dies Leupold 3.5-10 scope which I sold and 2 lbs of Retumbo powder.

It's all good. You own it. In time.. your can get ya a PRC. A buddy just bought one. Can't wait to shoot it and see what it's all about.

 

[Dawico]

I have a Weatherby Mk V accumark in 338-378 . I hand load for it,trying to develop a load for it. I'll use it for long distance steel shooting. Bought used for a once in a life time price. Highly doubt I'll ever go to Alaska for bear and moose. . Anyhow I'm wondering what I can expect for accuracy in this rifle and then live with it. Shooting it standing up isn't bad but off the bench is a different story.( Its a beast) I bought a Terminator T4 muzzle brake and its amazing how much recoil reduction there is,but the muzzle blast its also another story.

I have no idea on where to start for an accurate load for it or how accurate it might be.

I'd love to shoot it though.

 

[Ironworker]

I have some one recommending I shoot Barns 160 gr TTSX bullets. He says very accurate ,super fast and low recoil. But will these bullets with 120grs of powder burn my bbl up quicker ? I won't be hunting with this rifle just long range steel

 

[HKShooter65]

160 grain solid copper bullets are ultra light and enter the "exotic" area with the big .338 bore.

A buddy and I loaded some 225gr Nosler Accubond bullets 10 days ago and I those were at the LIGHT end of the .338 spectrum!

Working backwards......
The big 338-378 generates around 5,000 ft lbs with usual loads.

To achieve that energy the 160 grainers would be zipping along at about 3,745 feet per second.

Wow. Pretty zippy.

 

[HKShooter65]

That rifle should make for entertaining hand loading.

BTW.
If you like algebra....

Energy in Ft-Lbs = bullet gr. times FPS squared divided by 450,437.

I once knew how that 450,437 constant was derived. Would have to think a bit to recall it.