300 Rum question

[Scalloper]

I have a 700 with a 28" Krieger barrel with 34 rounds shot. It was shooting great groups, 210 Bergers 90gr Retumbo. but now 3.2" at 200 yds. Any suggestions?

I had a average of 1.22" for 5 shots when I first got the rifle after the barrel change.

 

[Scalloper]

I should add i bought a box of Hornady Percision ELDX just to see if it was my loads and those did about the same at 200 yds 2.56"

 

[Zero333]

Clean the barrel.

I use Barnes cr10 to get the copper out cause nothing else works as good.

Ive had some barrels that coppered horribly for the first 100 - 150 rounds. Then they settled down.

 

[TerryPohl]

Trying to edit my post after rereading, but what twist rate are you shooting?

 

[Scalloper]

1/9

 

[Scalloper]

I just scoped the pipe and then cleaned it with copper cleaner. I did consider doing this but i thought it would take more rounds then 94 to copper foul the barrel but it makes since. Thanks

 

[atblis]

My 300 RUMs look pretty nasty after about 40 rounds. That's when I typically clean them.

 

[ShootDots]

REMEMBER, you are pushing close to 100 grains of powder. Bullets are ripping down the barrel usually well in excess of 3100f.p.s. This creates LOTS of powder fouling even with CLEAN powders. Bullets sailing down the barrel at extraordinary speeds create loads of heat. This can and usually does aide in the depositing of copper in the barrel. I have a .300R.U.M. that also shoots Retumbo. I never shot it over about 15-20 rounds MAX before a good scrubbing. I also shot some RL-25 with 200 Accubonds. INSIDE of 20 rounds the accuracy deteriorated with the horribly dirty RL-25! That was one primary reason I went to Retumbo. 94 rounds in the barrel of a .300 R.U.M., there is little doubt that accuracy went south! A R-E-A-L-L-Y good scrubbing should bring it back to "normal", whatever that is in YOUR rifle...

 

[Scalloper]

Thanks all.

 

[Scalloper]

I went back and counted my bullets and loaded ammo i have only fired 34 rounds since new. Other then what the smith fired.

 

[46and2]

If and when possible get N570. Clean and de-coppering.
ShootDots is correct, velocity smears copper there's no way around it! And yes 94 rounds is a lot between cleanings on this cartridge. The good thing is that it should only take one, two at the most, round to foul (normalize) bore conditions to where POI, velocity and accuracy is consistent.
I will go 40 rounds max between cleanings.

 

[Scalloper]

I have some Tetra Gun copper solvent I normally use.

 

[Scalloper]

I got 80% of the copper out in two cleanings with Tetra. Do I need to remove 100%? Should I clean more?

 

[46and2]

Go ahead and see if you get 90 to 95%. Did you do a official barrel break in procedure?

 

[Scalloper]

Go ahead and see if you get 90 to 95%. Did you do a official barrel break in procedure?

I am still breaking it in.

 

[46and2]

I am still breaking it in.

Obviously, lol.
Most guys do a one shot, clean for 5 shots. 3 shots clean three times. 5 shots clean for a couple of times. Or until no or little copper is produced on the patch.

 

[46and2]

Try some Boretech Eliminator. Good stuff.

 

[Scalloper]

I was shooting 1.22" groups useing 90gr of Retumbo and 210 Berger VLDs in Feb-March at 3120fps temp 18-25 deg. I loaded 40rds. Now at 70-75 my groups open up to over 3" with the same batch I loaded. Could the temp cause this? I am going to run them across my crono tomorrow to see if the velocity has changed.

 

[46and2]

I was shooting 1.22" groups useing 90gr of Retumbo and 210 Berger VLDs in Feb-March at 3120fps temp 18-25 deg. I loaded 40rds. Now at 70-75 my groups open up to over 3" with the same batch I loaded. Could the temp cause this? I am going to run them across my crono tomorrow to see if the velocity has changed.

Try Reloder 33. I bet you won't be sorry. Despite the belief that RL powders are horribly temp sensitive my experience with 33 is it is predictable and quite behaved if ran at +90% case fill. However, I WILL NEVER shoot my hunting rifles over 80°. Why. I dont hunt at 80°.