Seating Depth and Accuracy

[sawacs]

After taking some throat measurements on a CBI 260 Rem Savage pre-fit barrel, I found out that the only bullets that I can seat properly at the neck shoulder junction, are the 120 grain Lapua Scenars. After measuring the 140 Amax, 139 Scenars, and the 140 Berger VLD's, it turns out that I have to seat these bullets farther into the case than desired (the beginning of the boat tail is below the case neck shoulder junction).

I realize that by seating the bullet farther into the case, I am taking up space for powder along with decreased velocity, but I am not worried about velocity. My question is will accuracy suffer by seating a bullet farther into the case than desired? The farthest my range goes out to is 200 yards.

Thanks,

Shawn

 

[dkhunt14]

I think it all depends upon the cases. If they are a different thickness at that point tensions will vary. If you get a donut from repeated firings and sizing's, accuracy will suffer. You could have the gun throated out to what you want. A gunsmith doesn't charge that much. You could also buy a throater and do it yourself. Matt

 

[ballison]

Shawn, is your max cartridge length limited by a short freebore or the magazine? Either way, have you tried the Berger 130AR? I have a 260 with a .110" freebore and max mag length of 2.95", and the 130AR's are perfect. I can get them to the lands with plenty of room to spare in the mag, and the bearing surface never gets below the neck.

 

[Jet]

sawacs

I'd test those longer bullets to see how they do vs the 120gr Scenar. You might be very happy with the results. If they don't shoot as well use Matt's advice.

I have a few 260s and they shoot best when you don't try to push them real hard. 40.7gr of H4350 is a powder weight that has worked great in every 260 I've done a load tune on.

Good Shooting.

Rich

 

[Raptor]

My 260s always liked a little jump sometimes a lot of jump.....

 

[sawacs]

Shawn, is your max cartridge length limited by a short freebore or the magazine? Either way, have you tried the Berger 130AR? I have a 260 with a .110" freebore and max mag length of 2.95", and the 130AR's are perfect. I can get them to the lands with plenty of room to spare in the mag, and the bearing surface never gets below the neck.

Although I do have a detachable box magazine, I see no reason to use it since I shoot single shot. In fact, I will probably change that out with a single shot plate. My cartridges are limited by a short freebore and the 130AR's sound like a great idea.

Regarding reaming out the throat myself, I would definitely consider giving that a whirl. I took a look at the PTG reamers and might give them a call next week to see what I need to get.

I am already researching my next barrel and am working on reamer specs to send off to the barrel maker. I should have done this from the start rather than purchase pre-made/pre-fit barrels: lesson learned

Thanks everyone for the information,

Shawn

 

[Das Capitolin]

After taking some throat measurements on a CBI 260 Rem Savage pre-fit barrel, I found out that the only bullets that I can seat properly at the neck shoulder junction, are the 120 grain Lapua Scenars. After measuring the 140 Amax, 139 Scenars, and the 140 Berger VLD's, it turns out that I have to seat these bullets farther into the case than desired (the beginning of the boat tail is below the case neck shoulder junction).

I realize that by seating the bullet farther into the case, I am taking up space for powder along with decreased velocity, but I am not worried about velocity. My question is will accuracy suffer by seating a bullet farther into the case than desired? The farthest my range goes out to is 200 yards.

Thanks,

Shawn

THIS. I got my CBI in 260 Rem for a Savage 12 LRP last year, and the first thing I discovered was the minimal free bore. They would likely take care of this for me if I returned the barrel, but my season starts in a few more weeks. All that being said, I haven't noticed much compromise in accuracy (I shoot out 330-850 yards in matches). My BTO is 2.22", which ironically makes for a 2.80" COAL using Hornady BTHP Match 140gn bullets.