Fibermark accuracy

[Powerwagon44]

So I just bought a brand new weatherby markv fibermark in 300 wby has a 28" barrel with break I reload and have for a older weatherby every one I've shot has shot amazing. I can't get a good group tried 10 different bullets each one in three different weights and just about every powder and primer  I can not get a decent group am I overlooking something I've ruled the scope out feel like I'm gonna Jill barrel before I get a good group even tried some different factory ammo only one I haven't bought is a box of weatherby it's self

[rockville]

With my .257 anything I throw down it (or out of it)the rifle shoots really good. With my 6.5-300 none of my handloads have really done great. It seems to like the factory Barnes load the best and then shoots the lesser expensive SP’s second best so far. I set a timer in between shots so I don’t heat up my barrel.
So my guess is, you just haven’t found what it likes best yet.
Might also be too long with your COL? We have a few reloading gurus here that can help tremendously.

[wyominghunter]

Check the torque on the action screws and try a box of factory Weatherby ammunition. That is what I would try next.

[Weatherby-SL]

Start back with the basics. If you've eliminated the scope, be sure you're shooting from a perfectly stable rest and are consistent with rifle hold, return to battery and consistent trigger pull.

Settle on a medium weight bullet (150 to 165) for the .300 WBY. Don't throw any charges, weigh each one. Be sure your data is correct for your loading manual; correct overall length etc.

As per above, be sure gun and scope mount screws are properly torqued.

Right out of the box, my .300 WBY Vanguard Synthetic shot three different handloads in less than MOA so it is probably just a matter of your finding the right combo. Try a factory box of ammo to check the difference between your load and Weatherby's.

Don't let it frustrate you; you'll be more proud of the load that you settle on when it finally groups well.

[oregonmarkv]

Power wagon, is it a fibermark or one of the new weathermarks? My weathermark 340 only likes 210 partitions so far, doesn't like boat tails such as ballistic tips or accubonds.

[oregonmarkv]

Also it should not be that hard to find a load, I suspect you may have a bedding problem.

[.257]

So far you have received a lot of good info. The only things l can add are, check your bases or base for contact to the action, you may have to bed them to the action.
Don't give up too soon. I  recently started loading for a new to me rifle and it took just over 40 rounds, adjusting a little bit at a time. Shooting 3 shot groups. This is all one powder and one bullet.
The point is the slightest adjustment in powder charge or seating depth can make all the difference
Good luck

[truck driver + 2]

If your not use to shooting a rifle with a brake the noise could be causing you to flinch also.

[oldchet]

If your not use to shooting a rifle with a brake the noise could be causing you to flinch also.

  +1. Happened to me until I put muffs over plugs.

[224KING]

Is it a stringing group,1st shot here then 2 others are touching 2 inches away,or just all over the place?

[catskinner]

A 300 wby shouldn't be that hard to get to shoot accurate, I agree on what the others have posted, on checking all your mounts and action screw to see if anything is loose. Btw, the proper way to torque your action screws is on Weatherby's website, under FAQ's. I would also check the barrel crown and try shooting some loads without the muzzle break, to see what happens. I'm curious, just what factory ammo did you try and how accurate was the groups? What kind of bullets, weights, powders, did to try reloading and just how accurate was the groups? and what was they doing just like 224 king asked?

Rob

[terminator]

With all the things you have tried I am surprised you have not tried the Weatherby Ammo.Give It a try and post Picts of your results.Good luck.

[Powerwagon44]

Thanks for all the info guys went bought a box of amo and did couple more reloads ended up finding hand load it really liked the factory weatherby ammo was  a 1" group the handloads made a .5 group one shot was due to me the other two where same hole it only took a few hundred rounds and a million variations but it's finally there

[Powerwagon44]

I've never met a 300 wby so picky in my life every one I've help load and including my old one we had .5 moa in first day of loads it ended up with nosler 180 ballistic tip CCI primer and 84 grains of 7828 in nosler brass

[wyominghunter]

I do quite a bit of handloading as well. When someone is having issues with a rifle using handloaded ammunition, the first thing I recommend is trying a box of premium factory ammunition.

It is just a good first step in the troubleshooting process. I’m glad you seem to have resolved the issue.