340 Weatherby question

[knifecat]

I recently got a 340 weatherby someone else had built and never used. Minus the action, it is what I would have built. The guy used a Mark V Japan 9 Lug for the build. Heres the question or issues. And wanted to get some thoughts. It is a proof research Carbon Fiber barrel AG Chalk branch stock 1 to 9.2 twist. Vortex Strike Eagle 5x25x56mm 34mm tube. EGW 20 MOA rail and vortex precision rings. I was told the smith shot 2 three shot groups and it was under an inch. The guy never shot it as his hunt fell through.

I have shot 225 Spire points, 225 interlocks, both of which I have variations of old boxes and new weatherby premium boxes, and 300 grain noslers. Best group I can get is about 1.4" at 100. I am not cleaning or moping between shots. I am unsure if barrel has been lapped and everything has remained tight to torque specs.

I am just disappointed in the overall performance. I take my weathermark and am under an inch. I have all kinds of other coopers and brownings that are just stock guns that are big calibers that are ragged hole guns. Is this potentially being a 1.4" gun the best I will get? Or will another 50 rounds break the barrel in that much to improve it. I would have thought this gun to be a ragged hole gun and it is not at this point.

Any thoughts???

 

[Catskills]

Personally, I'd try some different bullets before letting the disappointment set in. I don't know what your plans are for the rifle but I got stellar accuracy out of 210 partitions. While I'm not a huge fan, I'd also give Barnes a try as well as various weights of accubonds. I believe some hand loads will get you to under an inch.

 

[Panhandlin Pat]

Give hammers a try as well. They don't care about the long lead in a weatherby. It's the only bullet I could get to shoot good consistently in a 300 win mag of mine. Pricey yes, but so are the noslers I shot before switching.

 

[Dr. Vette]

As above, I'd switch bullets.
Mine likes Accubonds, and so far have not tried TTSX or Hammers in it. Those are the 3 I would consider.

 

[memtb]

You may have already done what I'm about to suggest! I would first off, eliminate any other reasons for lack of grouping. Is the scope, bases(s) and rings mounted securely. Can you swap out the scope to one that you have absolute faith in? How about barrel/action bedding into stock? Is the bore crown in good shape? Try to identify "if" you're getting fairly even bolt lug contact…..with 9 lugs, this may be an issue.

Just a few "out of the box" thoughts! memtb

 

[knifecat]

You may have already done what I'm about to suggest! I would first off, eliminate any other reasons for lack of grouping. Is the scope, bases(s) and rings mounted securely. Can you swap out the scope to one that you have absolute faith in? How about barrel/action bedding into stock? Is the bore crown in good shape? Try to identify "if" you're getting fairly even bolt lug contact…..with 9 lugs, this may be an issue.

Just a few "out of the box" thoughts! memtb

How do I verify contact? With all 9 lugs. I'm a shooter, not a smith, so try to speak English so to speak lol

 

[Idaho Lefty]

210 gr. Nosler Partitions, "CloverLeafed" 3 shots, Year after Year out of, my 25" Douglas Premium, 338 Win Mag Barrel ( German MK V action ) at, 2,970 FPS and was, an Elk,. "Thumper" ! Might Try, the 250 grain, Game Kings or, 250 gr. Elite Hunter, Bergers,.. also !

You probaby, WON'T get, ALL 9 Lugs to, Touch on a MK V ,.. Hopefully / maybe, 6 lugs, get Lapped to, "touch" and THAT's ,.. Plenty for, GOOD,.. accuracy !
Have your Gunsmith check, and LAP for good, Lug contact and, Headspace.
Find, Powder Charge / Velocity, THEN Move Bullets,.. IN / Out and, IF no good groups, TOSS Bullets and Move on to, the Next One.

 

[memtb]

I would get the lugs and action "squeaky" clean, free of any lube, color the contact side of all lugs with a magic marker, put the bolt back into the receiver, rotate the bolt several times….which should wear the magic marker color. Check all of the lugs and determine if the wear on the lugs is similar. Likely some wear (removal of the marker color) will be different from lug to lug. However, if the wear patterns are extremely different ( example some lugs show removal of the marker while others show virtually nothing) , this "may" be a contributing factor to your lack of accuracy! This method isn't an exact science…..just an indicator of the load balance between the lugs!

I hope that made a little sense! memtb

 

[Dr. Vette]

I own and work on (a lot of) Weatherby Mark V's, and I've never fussed with the lugs yet always been able to get exceptional accuracy.
In my experience it has been the bullet that makes the difference, next the powder.

 

[Reemty J]

Private message sp6x6 he is a 340 man he may have some loads that shot well. the 340 looks like a good round to me, will knock some large animals down well.

 

[Reemty J]

You want to try some 225 accubonds I think I have 32 of them…..

 

[knifecat]

Private message sp6x6 he is a 340 man he may have some loads that shot well. the 340 looks like a good round to me, will knock some large animals down well.

 

[knifecat]

This one was breathless on impact

View attachment 443078

At 286 yards with 340 weatherby. Different gun I have.

 

[Old Rooster]

This one was breathless on impact

At 286 yards with 340 weatherby. Different gun I have.

So it's not thew shooter!
Like others have said maybe try different bullets.