What freebore
- Thread starter avidflyer
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Ned Ludd
Silver $$ Contributor
The 0.169" fb of PTG's 223Rem ISSF reamer should work just fine. The base-to-ogive dimensions of the 90 VLD and SMK 90 are pretty close; with the SMK 90 being just a tick (~.015" longer). That's a sufficiently small difference that it would possibly even change solely due Lot-to-Lot variance.
If you find that your setup prefers seating depths for either of these bullets in the ~.020" off the lands region (as opposed to .005" to .010" into the lands), the 0.169" freebore is actually a little on the short side IMO. Bullets seated at .020" or more off the lands will put the boattail/bearing surface junction closer to the neck/shoulder than is ideal, leading to higher pressure at a given velocity. This can become an issue if you're running the 2850 fps node with a 30" barrel and H4895, which is pretty hard on brass. In that event, freebore lengths of .200" or slightly longer will work just fine with the 90s, but you may lose the ability to load the 80-grainers optimally if you go too long.
If you find that your setup prefers seating depths for either of these bullets in the ~.020" off the lands region (as opposed to .005" to .010" into the lands), the 0.169" freebore is actually a little on the short side IMO. Bullets seated at .020" or more off the lands will put the boattail/bearing surface junction closer to the neck/shoulder than is ideal, leading to higher pressure at a given velocity. This can become an issue if you're running the 2850 fps node with a 30" barrel and H4895, which is pretty hard on brass. In that event, freebore lengths of .200" or slightly longer will work just fine with the 90s, but you may lose the ability to load the 80-grainers optimally if you go too long.
MikeMcCasland
Team Texas F-T/R
I have some very limited first hand experience; so take this for what it's worth.
I picked up my new build this afternoon with a .170 Freebore and started pressing rounds out for its maiden voyage; if you're going to shoot 90s, then .170 is good to go, perhaps too short in some cases as Ned mentions. That said, he's spot on about losing the ability to run 80gr class bullets; you'll probably be stuck with 90s. I measured seating depths for an 80SMK and an 80.5 Berger, and both can hardly be seated into the case (we're talking .060 of bearing surface in the neck, only slightly more with the Berger). It's great for case capacity though; not even 25.3gr of Varget was a compressed load, hah.
There's no way you'll be shooting anything lighter than 80s without a massive jump to the lands; probably in the neighborhood of .1"-.2"
I guess it comes down to...how committed to running 90s are you?
Edit: See this thread; it likely has some posts that are relevant. http://forum.accurateshooter.com/th...tart-with-223-rem-29-1-7-600y-mr-ftr.3962943/
I picked up my new build this afternoon with a .170 Freebore and started pressing rounds out for its maiden voyage; if you're going to shoot 90s, then .170 is good to go, perhaps too short in some cases as Ned mentions. That said, he's spot on about losing the ability to run 80gr class bullets; you'll probably be stuck with 90s. I measured seating depths for an 80SMK and an 80.5 Berger, and both can hardly be seated into the case (we're talking .060 of bearing surface in the neck, only slightly more with the Berger). It's great for case capacity though; not even 25.3gr of Varget was a compressed load, hah.
There's no way you'll be shooting anything lighter than 80s without a massive jump to the lands; probably in the neighborhood of .1"-.2"
I guess it comes down to...how committed to running 90s are you?
Edit: See this thread; it likely has some posts that are relevant. http://forum.accurateshooter.com/th...tart-with-223-rem-29-1-7-600y-mr-ftr.3962943/
NorCalMikie
Gold $$ Contributor
Once you go long, you can't go back.
Nothing worse than not being able to reach the lands anymore with your favorite bullet because the lands have worn and you're using the heaviest bullet out there with a looong freebore.
Go short, use lighter bullets to start with and go heavier as the throat wears, and it will. Been there, sold one long throated barrel to someone that shot heavies. Custom chambers from now on with ZERO or next to nothing freebore.
Got a couple that are up to 60s now and still going strong.
Nothing worse than not being able to reach the lands anymore with your favorite bullet because the lands have worn and you're using the heaviest bullet out there with a looong freebore. Go short, use lighter bullets to start with and go heavier as the throat wears, and it will. Been there, sold one long throated barrel to someone that shot heavies. Custom chambers from now on with ZERO or next to nothing freebore.
Got a couple that are up to 60s now and still going strong.
You bringing it to CTSA next weekend?
MikeMcCasland
Team Texas F-T/R
Hopefully!
I'm going to break it in and do load dev on it both Sat and Sunday; if I can find something that shoots, I'll absolutely bring it out. If not, I'll fall back on my .260.
It's absolutely killing me though, the wife came home last night and reminded me that her nursing school graduation ceremony is that Saturday mid-afternoon; so there's a 50% chance I won't be there at all. I'm going to try and weasel my way out of it (you know, like a good/supportive husband). I paid for the damn thing, so that should earn me the right to skip out on it.
Ned Ludd
Silver $$ Contributor
Hopefully!
I'm going to break it in and do load dev on it both Sat and Sunday; if I can find something that shoots, I'll absolutely bring it out. If not, I'll fall back on my .260.
It's absolutely killing me though, the wife came home last night and reminded me that her nursing school graduation ceremony is that Saturday mid-afternoon; so there's a 50% chance I won't be there at all. I'm going to try and weasel my way out of it (you know, like a good/supportive husband). I paid for the damn thing, so that should earn me the right to skip out on it.
Absolutely trust me on this one - if you know what's good for you, you'd better be at your wife's Nursing School graduation ceremony. I'm sure she worked hard to earn that degree and is looking forward to receiving it, with her family in attendance. There will be other shooting opportunities, and wives have VERY long memories.
NorCalMikie
Gold $$ Contributor
I paid for the damn thing, so that should earn me the right to skip out on it.
Uh oh, bad ju ju thinking like that. You got a dog? Does said dog have a house? Is there enough room for both of you in said house? Is the dog small enough that you can throw it out? Any bridges close by that you can go live under? The only reason to miss the graduation is if you have to attend a funeral AND it damn sure better be yours!! Starting to get the BIG picture?
I'll say one thing, you've got balls for thinking that way BUT, my guess is you won't have them for long. Just remember, you have to go to sleep sometime.
Go ahead, go shooting and skip the graduation. It's been nice knowing you. And remember those two little words. "Yes Dear"!!
Watched my eldest daughter graduate from Nursing school at 40 years old. Wouldn't have missed that for the world. They only graduate ONCE!! BE THERE or else.
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