Cooper Model 92 Load Development

[treillw]

I've been struggling to find a load that my .300 win model 92 likes. I've been using 215 bergers and 212 eld-x bullets with H1000 powder. I've shot a bunch of groups with different powder charges and seating depths without any great results. Twice now I thought I found a good load and shot groups that are touching - .300" center to center of three shots. I run back home, happy as a clam, and load up 7 more bullets exactly the same to verify the load and then they shoot a 3" group when I return to the range to confirm the load. Blows my mind. I am waiting 5 minutes between shots and it has been between 20 and 40 degrees outside during my range time.


Anybody have a pet load that I could test out (with caution)?

 

[Apollo117]

If you're getting really small groups and then 3" groups it sounds like a scope or mount issue. Not a load issue.

Check your mounts and rings first. If you still have the issue, try a different scope that you know works.

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[treillw]

If you're getting really small groups and then 3" groups it sounds like a scope or mount issue. Not a load issue.

Check your mounts and rings first. If you still have the issue, try a different scope that you know works.

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I thought the exact same thing. I am using a March 3-24x52. I swapped it out for my buddy's ATACR 5-25 and shot 5 shots. I got a similar group to what I've typically been seeing with the March - shooting a 2" wide horizontal string. The load I tested was one that I got the .300" 3 shot group with using the March a few days earlier.

I guess that this still doesn't rule out the possibility that the March scope isn't holding zero. The gun with the ATACR weighs 20% more than it does with the March, which could totally change the harmonics of the gun - I notice that it recoils less with the additional weight. It wouldn't surprise me for a load that shoots good with the March to not shoot good with the ATACR. Maybe I just need to run some more tests with the Nightforce to see if I can get something to shoot good consistently.

 

[Apollo117]

Sounds like you're using two high quality scopes for testing. If the issue persists with both scopes, my next guesses are contact between the barrel and stock or maybe action screw torque. There may also be a burr or defect where the action meets the stock. If there is poor contact between the action and stock, then the recoil could be causing the POI change.

Are you maintaining a consistent shooting position, pressure, cheek weld, trigger pull for each shot?

Have you let a buddy shoot your rifle as well?

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[treillw]

Sounds like you're using two high quality scopes for testing. If the issue persists with both scopes, my next guesses are contact between the barrel and stock or maybe action screw torque. There may also be a burr or defect where the action meets the stock. If there is poor contact between the action and stock, then the recoil could be causing the POI change.

Are you maintaining a consistent shooting position, pressure, cheek weld, trigger pull for each shot?

Have you let a buddy shoot your rifle as well?

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I believe we checked the action screws when we remounted the scope. I'll double check them and take a look at the barrel. I have heard a few people online complaining that the March scopes do not hold zero, whether this is brand bias or whatever, who knows. I attributed it to that when I purchased it obviously, but now I'm beginning to wonder.

I'm trying to be as consistent as possible with every shot. Shooting prone with a rear bag. I feel rock solid. I can see my heartbeat move the crosshairs a half inch on the target with every beat. Trying to keep a gentle preload on the bipod. The bix'n andy trigger I had put in the gun is like butter.

I don't profess to be an expert marksman, but I have a hard time believing that I could be that terribly inconsistent to shoot .3" and then shoot 3" a few hours later.

Buddy did not shoot the rifle. But it might not be a bad idea, as he is a national champion long range shooter.

 

[wind gypsy]

This is just me but a thin fluted barrel, 1/2” muzzle threads, and heavy 300 WM loads don’t sound like a great combination for consistent precision from a number of standpoints but 3 MOA is definitely out of line.

I’ve been a march scope critic but I’ve never heard of zero retention issues.

Another thing to take a look at - make sure your front base mounting screws are not contacting the barrel threads through the receiver. It’s unfortunate how often mount manufacturers send out screws too long that make contact with the barrel, mess up the barrel threads and also hurt accuracy.

 

[ChrisAU]

Are you taking time to really dial in the parallax? That can drive someone nuts trying to shoot tiny groups, especially with either of those scope you've tried. 1" of parallax at 100 yards can easily make a rifle capable of shooting 1" groups shoot 2-3" groups.

 

[treillw]

Are you taking time to really dial in the parallax? That can drive someone nuts trying to shoot tiny groups, especially with either of those scope you've tried. 1" of parallax at 100 yards can easily make a rifle capable of shooting 1" groups shoot 2-3" groups.

Yeah, I'm trying to get the parallax out of the scope the best I can. I feel like I can never get it perfect - it's sometimes hard to tell what is parallax and what is me moving the gun as I'm moving my head around to check the parallax.

Maybe I need to put it in a vise to set the parallax at 100 yards and then keep my hands off the knob till I'm done!

 

[ChrisAU]

Yeah, I'm trying to get the parallax out of the scope the best I can. I feel like I can never get it perfect - it's sometimes hard to tell what is parallax and what is me moving the gun as I'm moving my head around to check the parallax.

Maybe I need to put it in a vise to set the parallax at 100 yards and then keep my hands off the knob till I'm done!

I feel the same way with my Zeiss 5-30x50. High mag scopes are very picky with it, and March scopes are notorious for it.

 

[ChrisAU]

And thinking about it, it could really be the culprit for a horizontal string group. I am much more consistent vertically with my cheek weld than I am horizontally.

 

[Apollo117]

And thinking about it, it could really be the culprit for a horizontal string group. I am much more consistent vertically with my cheek weld than I am horizontally.

Do you find yourself having to move your head often to get the correct eye relief? Could be that you need to readjust your scope in the rings for better eye relief.

While I setup a new scope I always have to pickup the rifle, close my eyes, bring the rifle to shoulder, and then open my eyes to test the eye relief. I find that this gives me a more natural feeling eye relief than if I leave the rifle on the vice when setting proper eye relief. If I skip this step, I notice I have to use a less natural feeling cheek weld. My neck feels squished up.

If you already do this, then your scope may just have a less forgiving eye box.

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