Help deciding... ftr 223

[jsthntn247]

CBTO may not be that meaningful as I'm using the Hornady caliper insert, which has a hole that is quite a bit smaller than some other brands and therefore seats further out on the ogive. COAL is 2.675"-ish.

I'm 2.708 coal averaged out from total lengths of my bullets. As you know bullets can vary nearly .020 in length as well. Even though Hornady inserts can vary, I'm coming to the conclusion that they (on average) are more dependable than base to tip lengths.

 

[Ned Ludd]

I'm 2.708 coal averaged out from total lengths of my bullets. As you know bullets can vary nearly .020 in length as well. Even though Hornady inserts can vary, I'm coming to the conclusion that they (on average) are more dependable than base to tip lengths.

In my hands, CBTO variance is usually noticeably less than bullet OAL, but you're right, they both will vary. I'd say your rounds are likely a fair bit longer than mine, which also matches reasonably well with the difference with the CBTO values; the caveat being what your intended seating depth relative to the lands is. I just finished loading up a seating depth test series, but haven't tested them yet and and don't know exactly where the final load will end up. However, at .015" off the lands, the CBTO of this load is 2.082" using length-sorted bullets (OAL) from the length group of 1.2490"-1.2505". Based on both measurements, you're currently about .030" longer (.028" or .033" depending on the measurement) than my rounds loaded at ~.015" off the lands. What is the intended seating depth of your load? If you're at about .010" or so into the lands, that would be about right.

 

[mao0720]

Is that with a 30" barrel?

yes my velocities of 2825 for the 90gr SMK and 2850 for the 80gr A-max are from a 30" barrel.

 

[jsthntn247]

In my hands, CBTO variance is usually noticeably less than bullet OAL, but you're right, they both will vary. I'd say your rounds are likely a fair bit longer than mine, which also matches reasonably well with the difference with the CBTO values; the caveat being what your intended seating depth relative to the lands is. I just finished loading up a seating depth test series, but haven't tested them yet and and don't know exactly where the final load will end up. However, at .015" off the lands, the CBTO of this load is 2.082" using length-sorted bullets (OAL) from the length group of 1.2490"-1.2505". Based on both measurements, you're currently about .030" longer (.028" or .033" depending on the measurement) than my rounds loaded at ~.015" off the lands. What is the intended seating depth of your load? If you're at about .010" or so into the lands, that would be about right.

I have to shoot these just off the lands. Too far in and I get horizontal, to far out and I get vertical. Do you know your exact freebore? Mine was done with a throating reamer so I don't have a clue. Just for future reference if I ever get a reamer made. If you can get your new barrel shooting off the lands, there is definitely something to the tighter freebore. Before every match I have to shine a bullet and chamber, back off the die, shine repeat until I land marks disappear when looking at bullet through magnifying glass..... seating depth is that finicky.

 

[Hosted]

Greg, my COAL is about 2.67-2.68. I still haven't gotten a perfect measurement though. It is getting easier to read the more rounds I get get down the barrel. It probably won't be a big deal as long as the throat doesn't go to fast. I have quite a few different Varget and H4895 loaded up for the weekend so we'll see how it goes.

 

[Ned Ludd]

Greg, my COAL is about 2.67-2.68. I still haven't gotten a perfect measurement though. It is getting easier to read the more rounds I get get down the barrel. It probably won't be a big deal as long as the throat doesn't go to fast. I have quite a few different Varget and H4895 loaded up for the weekend so we'll see how it goes.

I think you have it throated out just about perfectly, especially if you don't have to seat the 90s at, or into the lands. Good luck and let us know how it shoots this weekend.