Trouble grouping .375 H&H

In_die_bos

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Hello all,

I have a Winchester Model 70 in .375, Ive shot factory rounds through it of numerous grains and makes. I started reloading 300gr barnes for it to get a better group and I got a group to clover leaf at 100yds. I used that load to make more the same way and went out and shot. The groups were inches apart from each other, nothing more than 2 inches but definitely not the clover leaf I shot with the load when I first used it. I cleaned the rifle, Made sure the screws were tight, scope rings weren’t loose, and shot it again. I got the same results with 5 rounds of 3 shots I did not have a group inside 2 inches. I did however have multiple holes touching from different groups.
If this info helps I have tilley detachable rings, Reloaded barnes 300gr tsx, and shot it off of a lead sled.
Guidance or ideas on what to do would be great. Thank you to all in advance!
 

MRBlack

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Not sure what your cleaning regimen is, but it could be copper fouling. Copper builds up really fast on the big bores. I use Montana X-Treme Copper Killer and have had good results. If the barrel is copper fouled, the patches will have a bluish tint around the rifling marks. You can also shine a flashlight at an angle by the muzzle crown and the copper will be apparent on the rifling.
 
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In_die_bos

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Not sure what your cleaning regiment is, but it could be copper fouling. Copper builds up really fast on the big bores. I use Montana X-Treme Copper Killer and have had good results. If the barrel is copper fouled, the patches will have a bluish tint around the rifling marks. You can also shine a flashlight at an angle by the muzzle crown and the copper will be apparent on the rifling.
Thank you, I have bore tech eliminator and it seemed to work well for the barrel
 

SRvet

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What was your average group size before and after? How many times did it cloverleaf? If it was just once then that doesn’t mean much to be honest. Has the rifle been glass bedded? That has sorted out most of my two together then one away woes in the past. Decoppering may help but could also make it worse in some rifles that may have a rough bore. The other possibility is that your scope has gone for a walk? May be worth trying another if you have a spare.. Rifles can be truly frustrating things sometimes
 

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The Bore tech usually does a good job on copper. Have you tried changing your seating depth? That can make a lot of difference. How's your trigger? Some are pretty stiff and that can cause problems for some of us. Are you using same primers and powder from same lots? Powder can vary lot to lot and may have an affect. Not sure about your detachable rings. Some folks have great luck with them and others not so much. Few more things to consider anyway. Good luck.
Bruce
 

Ridgewalker

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Just some things I have found.
In my 375 MRC the Barnes shoot to half the size groups after dirtying the barrel with cheap ammo (Hornady, Federal, PPU, etc). So before I go to Africa, I foul the bore and test my load, then take the dirty rifle with me.
As mentioned Barnes seating depth can be critical. The deeper the better often.
Leadsleds can be finicky, ie, be certain your hold is identical every shot. Be sure the front sling stud isn’t hitting the front bag. I prefer one hand resting with downward pressure on the scope.
Are action screws firmly tightened?
Sometimes a powder bullet primer combination will cause two clustering and one flier. If you’ve only fired one group that all three rounds clustered, I doubt you have the right combination. JMT Be patient. You’ll find the right combination. To me this is all fun times trying to find one good combination, then another, and another. Then the powder you used is gone everywhere you try to buy it and the process starts again.

Best of luck finding “ your” perfect load!
 

John J

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I had inconsistent groups with my 375. Gunsmith found the stock not fitting correctly. He thinks the front and rear screws were fighting each other. Could be a scope or mount issue as well?
 

sestoppelman

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What powder are you using and what type of velocity are you trying to achieve?
I have had more finicky rifles cured by Barnes Triple Shocks than any other bullet so you are on the right path with it I think.
 

MMAL

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I had a model 70 in .300 win that did something very similar. I free floated the barrel, did not glass bed it just took some stock material away and something not mentioned but check the muzzle. Makes sure is is round and not chipped, bend, marred whatever. Any inconsistency will cause flyers. Good luck.
 

KEC

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I agree with swapping scopes if you have a known good one to try. Especially if you have been shooting much from a lead sled, they can be rough on stocks & scopes as there is no outlet for the recoil force. When we shoot from bags we absorb the shock.
 

Hogpatrol

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+1 on swapping scopes but curious as to your make and model of scope. Aside that, I'd dump the lead sled and shoot the number of rounds you can stand for load development from bags or a rest.
 

PARA45

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Very good advise above. Also, if you are going to change things, do them one at a time. Otherwise you'll continue to chase your tail. BTW, can you give us a rundown of what you are using? I.e. brass type, powder, primer, etc, etc. Sometimes we get lucky with one powder, bullet and primer combination. Other times, we have to see what the rifle likes, and that my friend is the key.
 

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1st thing to do with any new factory rifle is to re bed the action and free float the barrel. If you could pillar bed it even better. There are lots of how to videos out there and it isn't that hard. Just be slow and careful to not lock it into the stock use plenty release agent OR pay a gunsmith shouldn't be that much. Next be careful with shooting too much off a lead sled that is a recipe to ruin even a expensive scope! I have a hunch as other have said that you probably already have a scope issue too. Be patient and enjoy this is what makes shooting fun you will get it sorted out and learn along the way lots of knowledge on this forum!
 

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Hello all,

I have a Winchester Model 70 in .375, Ive shot factory rounds through it of numerous grains and makes. I started reloading 300gr barnes for it to get a better group and I got a group to clover leaf at 100yds. I used that load to make more the same way and went out and shot. The groups were inches apart from each other, nothing more than 2 inches but definitely not the clover leaf I shot with the load when I first used it. I cleaned the rifle, Made sure the screws were tight, scope rings weren’t loose, and shot it again. I got the same results with 5 rounds of 3 shots I did not have a group inside 2 inches. I did however have multiple holes touching from different groups.
If this info helps I have tilley detachable rings, Reloaded barnes 300gr tsx, and shot it off of a lead sled.
Guidance or ideas on what to do would be great. Thank you to all in advance!
In die bos, was that maybe a new batch of powder? and may I ask what powder you are using? And do you have access to a chronograph?
 

bruce moulds

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the old accuracy problem!
years of shooting fclass rifles, properly put together by benchrest gunsmiths has taught me this.
yes loads will improve accuracy, but in a correctly built rifle with good parts and good bullets, any load will give good hunting accuracy.
with the right loads, these guns will put ALL shots into 1/2 moa if you can read the wind (another subject altogether).
what will put shots out of the group under these circumstances is hold and squeeze technique, problems of which are magnifies by lack of follow through.
absolute consistency of how the gun sits on the bags, recoils, and bag hardness , will not allow realization of full grouping potential.
From this I have made all my hunting rifles of good parts, properly put together by good gunsmiths.
this does not preclude mauser actions, but they along with Winchester etc do need a little trueing up, primarily squaring the front of the receiver to the bolt hole.
these guns from 223 to 375 will put ALL shots of almost any load into 1 moa or less. (not just the occasional group).
for hunting this is way more accuracy than required.
just load so ammo will function in the gun, and settle on a sane velocity/pressure goal , and go hunting.
consistency of ammo loading and even more so shooting technique are the main issues.
it is easy to blame a gun for poor technique, especially when the gun is loud and comes back hard and fast.
I know I can shoot a 17 mach 1v better than a 375, and even a 223 better than a 300 win.
for me 30/06, 7mm rem mag is max for easier accuracy.
I have to work hard to shoot small groups with guns bigger than that.
bruce.
 
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sestoppelman

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Be great if he came back with more info....:unsure:
 

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