Frank.... I hear you, but it just isn’t going to happen. Like I referenced above regarding the .277 150 LRAB.... once you get close to the edge in stabilization, the BC drops. This has been shown several times... most recently in an article involving two .22-250’s; one a 1-8” twist, the other a standard 1-14” twist. Every bullet fired in the 1-8” had a higher measured BC than the exact same bullet, at the same velocity, out of the 1-14”. The difference is small, until you get into the 60+ grain bullets, and then you can see how the lack of RPMs effects the BC, even though the groups look fine. It’s easy to assume that because the load/billet is accurate, that it’s stable and you’re getting the full BC.... but you’re not.
Let say we built a .25 115grain ABLR... nearly identical to the 115 Berger... maybe a touch longer to try and eek out that last little bit of BC trying to get to .500. If you shot it in a 1-8” barrel... it’d probably get that full .500.... but in a standard 1-10”, it’s probably going to be more like .450.... because it’s just barely “stable”. Add low pressure/altitude, and some cold weather... and you could lose it all together.
Here’s a personal example. We bought two identical Tikka .243s (1-10” twist), one for my brother who lives in CA at about 500’ elevation.... and one for myself, I live at about 5000’ elevation. I built a load for them both here in CO that hammered 105 HPBTs (.500ish BC) into 1/2 MOA groups at 500 yards. We were stoked, as both rifles shot this load like a champ. We loaded up 50 for each gun and my brother headed back to CA with rifle in tow. About a week later he called me all kinds of frustrated.. that same rifle/load wouldn’t hit a piece of paper at 100 yards. Once he got down in altitude, the 1-10” wouldn’t stabilize the 105s. Mine was fine... until it got below about 20*, then I had some issues too. Just barely stable can look like everything is fine... until some variables change slightly... then you can be in trouble.
That’s why about .450 is all you’re gonna get in a 1-10” .25 cal barrel. Because there needs to be a little wiggle room, just to make sure it really is stable, under a broad range of circumstances.
Make sense?
Let say we built a .25 115grain ABLR... nearly identical to the 115 Berger... maybe a touch longer to try and eek out that last little bit of BC trying to get to .500. If you shot it in a 1-8” barrel... it’d probably get that full .500.... but in a standard 1-10”, it’s probably going to be more like .450.... because it’s just barely “stable”. Add low pressure/altitude, and some cold weather... and you could lose it all together.
Here’s a personal example. We bought two identical Tikka .243s (1-10” twist), one for my brother who lives in CA at about 500’ elevation.... and one for myself, I live at about 5000’ elevation. I built a load for them both here in CO that hammered 105 HPBTs (.500ish BC) into 1/2 MOA groups at 500 yards. We were stoked, as both rifles shot this load like a champ. We loaded up 50 for each gun and my brother headed back to CA with rifle in tow. About a week later he called me all kinds of frustrated.. that same rifle/load wouldn’t hit a piece of paper at 100 yards. Once he got down in altitude, the 1-10” wouldn’t stabilize the 105s. Mine was fine... until it got below about 20*, then I had some issues too. Just barely stable can look like everything is fine... until some variables change slightly... then you can be in trouble.
That’s why about .450 is all you’re gonna get in a 1-10” .25 cal barrel. Because there needs to be a little wiggle room, just to make sure it really is stable, under a broad range of circumstances.
Make sense?
