Load Development Help - Rifle Went Out of Tune

[treillw]

I'm relatively new to tuning rifles to have great accuracy. I have a 300 win shooting 215 bergers with 75 grains of H1000 at 2740 fps. For the past couple years it has been a half minute rifle. This year it has gone out of tune and is shooting about 1.1 moa. What is the best approach to finding the tune again?

My first guess is to chase the lands - they are probably wearing by now. So I loaded up a few rounds with the same powder charge and started seating the bullets longer in .005" increments. You can see in the photo below that things didn't improve. I'm confident that the fliers in the original load are not my fault. I have shot a lot of shots with it since it has gone out of tune and seen many fliers on shots which feel solid.

What would you try next? I almost feel like I should go shorter with the OAL, since the original load still shows so much promise. Maybe vary the powder charge slightly?

I've also thought about playing around the 3.920" length, but I would need to shoot quite a few more rounds to confirm that load is indeed in the .7 moa ballpark; it could very easily open up to 1.25 moa with another shot.

What would you do from here?

Thanks!

 

[wildwilderness]

Couple questions-

Have you tested the velocity? Is it still shooting the same speed?

What is the cleaning situation? Scrubbed down back to a spotless bore? bare metal?

How many total rounds do you estimate through the barrel?

 

[treillw]

So I haven't shot it over a chronograph, but I've validated my trajectory out to 740 yards and it is the same - therefore the velocity should not have changed.

I could have been a little more diligent with my cleaning regiment over the past couple of years. The gun was shooting well, so I did not clean it. Once things started acting up, I clean it and then continued shooting. These groups are after cleaning. I don't know that I cleaned it to spotless bare metal, but I tried to clean it well with butch's bore shine. let it soak pretty long and scrubbed it well with a nylon brush.

I would say i have 250-400 rounds though the barrel. Guessing - I could probably get a more accurate number if needed. I should have kept better track of it.

 

[treillw]

I should add that it is a new powder and bullet lot. I got 1000 bullets now and an 8 pound jug of h1000.

 

[willfrye027]

I should add that it is a new powder and bullet lot. I got 1000 bullets now and an 8 pound jug of h1000.

This could be your issue. Also once you get the lands worn in a bit pressure/velocity etc can change. It can take more powder to get the same velocity.

Between the new lot of powder and potentially increased wear on the bore I would try tuning charge weight next

 

[Mulyhuntr]

Is there enough bearing surface in the case neck at 3.9"+ ? Seems really long but I've never loaded that combo.

 

[treillw]

Is there enough bearing surface in the case neck at 3.9"+ ? Seems really long but I've never loaded that combo.

I'm measuring with a comparator and anvil base, so take those measurements with a grain of salt.
It has shot great at that length for years... so I assume that's not the issue.

 

[JFK]

You didn’t mention it so I’ll ask…you have checked all action screws and confirmed that your scope rings/bases are tight?

 

[WeiserBucks]

I should add that it is a new powder and bullet lot. I got 1000 bullets now and an 8 pound jug of h1000.

This is your answer right here 1000%. You need to start load development over again. It will be somewhat close to the original load but you need to start over with new components even if they're the same type used in the past.

 

[treillw]

This is your answer right here 1000%. You need to start load development over again. It will be somewhat close to the original load but you need to start over with new components even if they're the same type used in the past.

That's kind of what I figured.

Should I keep the seating depth the same and play with the powder charge to start? In what increments?

 

[WeiserBucks]

That's kind of what I figured.

Should I keep the seating depth the same and play with the powder charge to start? In what increments?

If it were mine I'd keep the seating depth the same to begin with as the bullets are likely the most consistent part of the equation. As far as powder charge, was the 70 grains you were using max or just best accuracy? Regardless I'd drop to 73 or so and work it up to pressure .5 grain at a time. Once you get the safe velocity you want then play with seating depth if necessary. If you're also starting over with new brass you may want to start at an even lower charge.

 

[Travis Bertrand]

I would start by going through the rifle and torquing everything back down to spec.

I then would remove all copper from the barrel then put 20 or so down the tube and recheck groups along with es/sd.

If that doesn’t work, you need to start load development again but not necessarily from scratch. Shoot it over a chrono and match the speed as previous load. You should be within .5 grains. Then adjust seating depth.


Wait, what am I saying. It’s obvious that new jug of h1000 is the issue. I’ll take it off your hands for ya


Sent from my iPhone using Tapatalk

 

[LaHunter]

I'm relatively new to tuning rifles to have great accuracy. I have a 300 win shooting 215 bergers with 75 grains of H1000 at 2740 fps. For the past couple years it has been a half minute rifle. This year it has gone out of tune and is shooting about 1.1 moa. What is the best approach to finding the tune again?

My first guess is to chase the lands - they are probably wearing by now. So I loaded up a few rounds with the same powder charge and started seating the bullets longer in .005" increments. You can see in the photo below that things didn't improve. I'm confident that the fliers in the original load are not my fault. I have shot a lot of shots with it since it has gone out of tune and seen many fliers on shots which feel solid.

What would you try next? I almost feel like I should go shorter with the OAL, since the original load still shows so much promise. Maybe vary the powder charge slightly?

I've also thought about playing around the 3.920" length, but I would need to shoot quite a few more rounds to confirm that load is indeed in the .7 moa ballpark; it could very easily open up to 1.25 moa with another shot.

What would you do from here?

Thanks!

View attachment 352953

what scope & mounting system do you have? This could be a scope issue. You may want to eliminate this as a possibility. Sometimes, scope failures are not so dramatic that your POI is 10" off at 100. I have chased my tail before with a scope failure thinking it was me or the load.