6 BRDX button rifled barrel question

[alphapygmy]

I built myself a rifle for my local F-Open 600 yard shoots last year. An X-caliber blank as a fire form barrel and a Bartlein for the matches. To save my Bartlein over the winter I started playing with the X-cal barrel. It has turned out to be the most accurate barrel I've ever owned. I do 4 shot groups at 100 yards for load work and it has turned in several groups around .080" and a best of .072" and lots of groups in the ones. I've only been out to 600 a few times but notice a pattern forming. After my 2 sighters the first 8-10 shots are X's then it goes downhill the final 10 shots. It's still shooting good enough to get me a couple 200's and a 199 but most the X's come in the first half of my string of fire. I was wondering since it was button rifled is there some kind of stress that's coming out when the barrel is getting hot? My Bartlein is much more consistent over the course of fire but not as accurate overall. Any ideas on what would cause this?

 

[DanSavage]

Good question,, I think it is possible but more than likely it could be that the load is a few tenths high.

I have a McGowan buttoned .223 that will go both ways during a match with a certain load that had a narrow tune window. It may shoot far less x's first 10 then a 10 x on last string. Or a 10 x first string then maybe a 6x last 10 shots. I had to work up a different load for it. This was only 300 yards btw.

 

[Boyd L.]

...I do 4 shot groups at 100 yards for load work and it has turned in several groups around .080" and a best of .072" and lots of groups in the ones. I've only been out to 600 a few times but notice a pattern forming. After my 2 sighters the first 8-10 shots are X's then it goes downhill the final 10 shots.

...I was wondering since it was button rifled is there some kind of stress that's coming out when the barrel is getting hot? My Bartlein is much more consistent over the course of fire but not as accurate overall.

Interesting. Although I don’t compete, I have a similarly shaped trend happening with my Criterion barreled 6BR, which is slap button rifled. I normally shoot at 300. When clean it takes 6-9 shots for 3 shot groups (with 95 TMK/107 SMK/107 Noslers) to print in the sub 1/2 moa range. When the round count for that session gets up to 20-plus the groups tend to grow to 1/2-3/4 moa.
My practice is approximately 1 minute between rounds (usually a bit more) so granted conditions may be changing and my wind skills are undoubtedly substandard. I’ve stopped shooting a couple of times (when the groups start to open up) and returned the next day (without cleaning) and groups are usually in the 3/4 moa range so I’m leaning toward a carbon/copper issue.

My speculation really makes it clear that criterion defined controlled data gathering is necessary. For more talking fodder if nothing else.

 

[JBT47]

Interesting. Although I don’t compete, I have a similarly shaped trend happening with my Criterion barreled 6BR, which is slap button rifled. I normally shoot at 300. When clean it takes 6-9 shots for 3 shot groups (with 95 TMK/107 SMK/107 Noslers) to print in the sub 1/2 moa range. When the round count for that session gets up to 20-plus the groups tend to grow to 1/2-3/4 moa.
My practice is approximately 1 minute between rounds (usually a bit more) so granted conditions may be changing and my wind skills are undoubtedly substandard. I’ve stopped shooting a couple of times (when the groups start to open up) and returned the next day (without cleaning) and groups are usually in the 3/4 moa range so I’m leaning toward a carbon/copper issue.

My speculation really makes it clear that criterion defined controlled data gathering is necessary. For more talking fodder if nothing else.

What does “slap button rifled” mean?

 

[Boyd L.]

Love “auto-correct for whatever purpose” on an I-phone. It should read “also button rifled”. Though I have to say, “slap button rifling” has a great marketing ring to it. Mysterious, yet goofy.

Gotta love technology.

 

[kris bassett]

I

Love “auto-correct for whatever purpose” on an I-phone. It should read “also button rifled”. Though I have to say, “slap button rifling” has a great marketing ring to it. Mysterious, yet goofy.

Gotta love technology.

I want my next barrel to be slap button rifled! There has got to be an advantage to it! Lol