.300 Win Mag load issues

[Fish4Fun]

I have a question about hand loads for a .300 Win Mag.   
My brother has a Browning Hells Canyon Speed in .300 Win Mag. The loads him and our friend made for the gun will shoot 3 shot single hole groups at 100 yards. They are seriously accurate at 100    At 300 yards they are now 6” - 7” HIGH above the bullseye. If you hold 7” low it puts them dead center bullseye. 
So, what if any ideas does anyone have that is causing the bullet to keep climbing.
Sight in is  2” high at 100 yards and  the bullet is hitting at 7” high at 300 yards. 
What would cause the bullet to keep on gaining elevation the farther it travels
Could this just be a bad load recipe  ?

They were loading  H1000 powder with 180 bullet

[Taco280AI]

Bad shooting form? Bad scope? Are you dialing @ 300 or holding dead on?

[jrebel]

Are they grouping well?? 

[Fish4Fun]

Dead on hold with no scope adjustment. Doesn’t matter who is behind the trigger the down range is always still climbing. 

[Fish4Fun]

Are they grouping well??

At 100 yards 3 shot groups are under 1/2”   
At 300 yards 7” high and 2” groups

I want him to shoot some factory loads and see what the results are

[2MANY]

Heat waves off the barrel?

[jrebel]

This defies gravity and doesn't make sense to me.  There has to be a mechanical error in the gear or the shooter.  If it continues to group sub MOA, I would say the load is solid.  In most cases, he should be zeroed at 200 yards if he is a couple inches high at 100.  This would put him 7 inches low at 300.  My numbers are approximations based on velocity, but would be very close. 

If it were the gun, I would expect the grouping would not be sub MOA.  If were the scope, I would say he has a serious tracking issue if he is dialing.  If it is the shooter, I would look at how he is shouldering the rifle, if the sling stud is hitting the bag on recoil, etc.  Again, If it is him, I would expect his groups would open up and not be sub MOA.

What's it do at 200 yards?? 

[crabcreekhunter]

Shooting off a bipod on a hard surface and getting some “bounce”?  I’ve had it mess with me quite a bit but usually not that consistent.

[Fish4Fun]

Not sure where he is at 200 as we had target set dead on at 300.  To me this is just mind boggling how it is shooting.  We shot just last week before deer season, luckily from our elk stand the shots are under 200 yards and they are big critters for a target.  Need to do some load testing after elk season to figure this mess out. My .300 Weatherby is money every year shooting Weatherby ammo. Shooting the weatherby I don’t mess with hand loads so this is all new to me.

[Fish4Fun]

Shooting off a bipod on a hard surface and getting some “bounce”?  I’ve had it mess with me quite a bit but usually not that consistent.

We have a shooting bench with a rest on it with sand bags under the stock at the butt.  I shoot my Weatherby off the same setup and it is on the money.  3” high at 100 and dead on at 300. So the bench and table are not an issue

Just mind boggling that the load is still gaining elevation

[Blacktail Sniper]

Rezero at 300, then see what happens to placement at 100?

[Fish4Fun]

Rezero at 300, then see what happens to placement at 100?

Good idea 👍

[GWP]

My first thought was tall scope mounts.

[grundy53]

This has nothing to do with the load.

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[Jpmiller]

I’d imagine something is wonky with the scope? I’m not an expert or a gunsmith but that’s the only thing I can think of that would make sense and not be breaking physics.

Maybe you’ve got something you can market to the military or those extreme long range guys 

[Snakeriver]

 Zero it at 100.  2" inch group at 300 is barely above 1/2 moa which is what its shooting at 100.

[Snakeriver]

Zero'd at 100 you should be around 9 inches low at 300. Thats just a guess though as I dont have a 300 wm.

[MeepDog]

Do you have incredibly high scope rings? Maybe it's a case of catching it on the way up and then on the way down like a shotgun slug.

[cooltimber]

cheek weld ?

[Mtnwalker]

This is not a ring height issue unless your rings are 4 inches tall. My guess is:

Bad zero. Shoot a 7 shot group at 100 with no adjustments between shots. 3 shot groups aren’t sufficient when diagnosing issues

Loose component or scope failure.

Operator error.

 

[Fish4Fun]

Next time out I am going to have him shoot a factory load at the same distance as the hand loads.  Compare one to the other side by side. I am now thinking a scope that is out of whack. He has the Leupold 4x14 CDS on there.  After elk season, do more testing and then send back to Leupold for a tuneup

Thanks for all of your ideas, I have been scratching my head about this rifle.

[Taco280AI]

Whatever it is I'd find and fix it now if it's going to be used for hunting. If it's the scope, my guess, who says it won't mess up more?

[Fish4Fun]

Whatever it is I'd find and fix it now if it's going to be used for hunting. If it's the scope, my guess, who says it won't mess up more?

Not my rifle, if it was it would have been fixed long before now.

[chukar58]

Have you ever been able to shoot a good group with this load at 300 yards?  In theory the bullet should be dropping out at 300 yards,  my suspect is bad mount or perhaps scope or action screw is not torqued and loose.