Frustration with Sierra 107gr MK - Help !!!

[BadRambo]

Howdy All ---

Well, I just got my Ruger #1 rebarreled for 6BR with a 1:8 twist at 24" length. I proceeded to make up some moderate loads using 28.5gr of Varget and the Sierra 107gr, torched with a CCI450 in Lapua brass.

Much to my shock, these were all over the paper -- about a 6" radius at 100 yards. And with the signs of keyholing. Argh.

Is my situation,gun and ammo) recipe marginal for the 107gr MK ?? I have made up some more loads with 30.0 gr of Varget but have not shot them yet.

What say out there veterans of the 6BR and the 107gr MK ???

What is wrong?? Thanks --- Bob :,

 

[Cheechako]

Bob

First things first. Accurately measure the twist.

Report back

Ray

 

[BadRambo]

Hi Ray --- oh, yeah. That was my first thought when I saw the results, that I did not get what I ordered.

It measures a solid 1:8.

Bob

 

[BadRambo]

I should have noted that I tried some older Remington factory rounds,100gr) which I had around, and they grouped at about 1" without even trying.

Bob

 

[BadRambo]

Well, hell -- I used a better measurement technique and found my problem. It is not 1:8.

Thanks anyways guys. Arrrgghhhh.

 

[BadRambo]

Hi There ---

The barrel ended up with a 1:10 twist rate. This was clearly a screw-up at the maker. Too bad I had to wait a year for it too.
This explains the performance I was seeing perfectly.

Someone is going to get an ear-full tomorrow.

Thanks --- Bob