Transitional rifling

[Trnelson]

I'm eyeballing having a bartlein transitional rifling barrel made. I'm thinking about a 264 win mag chamber 1/14 to 1/7 that finishes at 26". I went totally mega ELDX crazy and bought enough for my current 264 win mag 1/9 twist barrel to be done dealing. My complaint is now I get the 'pleasure' of de coppering about every 50 rounds. It is concentrated heavily in the first 3 - 4" round count is 571. Current load goes 3,168 fps SD 9 over the magnetospeed with Norma 217 drops verified out to 750
Thoughts? Experiences? Profile recomendations?

 

[Frank in the Laurels]

Remember trying to find casings .... I'd switch cartridges also, a 7mm rm or .300wm mag will do the same thing with less pain today and tomorrow, ..both will be similar with 140/150 grain bullets and much much easier on the barrel/throat..just a thought.

 

[Trnelson]

Remember trying to find casings .... I'd switch cartridges also, a 7mm rm or .300wm mag will do the same thing with less pain today and tomorrow, ..both will be similar with 140/150 grain bullets and much much easier on the barrel/throat..just a thought.

I HAVE 250 pieces of Nosler 264 brass, 700+ ELDX 143g bullets for my existing 264 win mag. I also have both 7mm and 30 magnums.

 

[Capt RB]

Try to find a load for one of the de-coppering powders. I would think RL26 or IMR7977 should be close enough in burn rate to your current load to get to that node. The other option is a coating BN, Danzac moly etc .
I would think that much gain twist would be less than optimal. 9.5or 10 to 7.7 with most of the gain in the last 3rd would be something more in line with what I've seen in other calibers. Particularly 7mm F-class rigs. I've only shot a gain twist in a 22 rf so idk other than seeing them at the range about 5yrs ago. In the 22 I was told it helps consistency in the less than stellar ammo. That gun shot well enough to get that offer you can't refuse at the club

 

[Trnelson]

Try to find a load for one of the de-coppering powders. I would think RL26 or IMR7977 should be close enough in burn rate to your current load to get to that node. The other option is a coating BN, Danzac moly etc .
I would think that much gain twist would be less than optimal. 9.5or 10 to 7.7 with most of the gain in the last 3rd would be something more in line with what I've seen in other calibers. Particularly 7mm F-class rigs. I've only shot a gain twist in a 22 rf so idk other than seeing them at the range about 5yrs ago. In the 22 I was told it helps consistency in the less than stellar ammo. That gun shot well enough to get that offer you can't refuse at the club

Interesting. I would have thought a slower twist steady increased over the length would work better. In my current barrel (9 twist) I see 90%+ of the deposits in the first four inches of the barrel. Thank you for sharing.

 

[jakelly]

If you can find 7RM brass you can find 264 brass. Your throat sounds firecracked, polishing will help, but you're seeing the beginning of the end. This is why the 6.5 SAUM is so appealing. If you're gonna do another, try some H1000 to help barrel life. I wouldn't go lighter than Bartlein #3.

 

[AZShooter]

TrNelson:

I own several Bartleins. Didn't know they offer a gain twist option. Thanks for bringing that to my attention. These sites are always so informative.

Are you using a bore scope to "see 90%+ of the deposits in the first four inches of the barrel"?



I use a Hawkeye and see more copper deposits in the last 1/3 of the barrel. I see more carbon fouling in the first third.

I watched my SS 28" lilja 3 groove in 257 Weatherby slowly wear out. I finally pulled it at 1100 rounds as it would only shoot 10 shots then foul so severely that accuracy suffered.

I would think you have more life in your 264.

Perhaps a different approach to cleaning could help things. What products do you use to clean your barrel.

Always interesting hearing what others encounter with their rifles.

 

[J E Custom]

Interesting. I would have thought a slower twist steady increased over the length would work better. In my current barrel (9 twist) I see 90%+ of the deposits in the first four inches of the barrel. Thank you for sharing.

There have been lots of post and discussions on gain twist barrels and you should do a search and read them before you make the decision to go this way.

Most that go with gain twist normally chose a twist that is only one inch apart. (1 in 10 to a 1 in 9)
But if you think about it at the beginning, the bullet is starting at a much slower velocity and bullets have no problem engraving.

J E CUSTOM

 

[Edd]

On a 9" twist 6.5 mm barrel, the angle of the rifling is only 5°.

 

[Trnelson]

There have been lots of post and discussions on gain twist barrels and you should do a search and read them before you make the decision to go this way.

Most that go with gain twist normally chose a twist that is only one inch apart. (1 in 10 to a 1 in 9)
But if you think about it at the beginning, the bullet is starting at a much slower velocity and bullets have no problem engraving.

J E CUSTOM[/
Interesting. Thanks for the perspective.

 

[Mateo]

I'm using gain twist in my 6.5 Sherman shortmag. It's 1:16-1:8. I find i'm not getting pressure signs where others are. It might be a bit faster too. But i haven't done any in depth testing with a straight twist barrel in the same chambering so can't say for sure either way. Just comparing to what others have out there. My local barrel maker, who is well known out here for bis exceptionally tight machining tolerances, recommended the amount of gain.

 

[Trnelson]

I'm using gain twist in my 6.5 Sherman shortmag. It's 1:16-1:8. I find i'm not getting pressure signs where others are. It might be a bit faster too. But i haven't done any in depth testing with a straight twist barrel in the same chambering so can't say for sure either way. Just comparing to what others have out there. My local barrel maker, who is well known out here for bis exceptionally tight machining tolerances, recommended the amount of gain.

How is the barrel in terms of jacket deposits? Your velocity should be very similar to what I'm running currently. The entire reason I'm examining a gain twist is to hopefully amelgamate or at least significantly reduce the fouling I'm seeing in my current barrel. How did you decide to layout the transition of the twist rate? Steadily increased or something else?