yes, I have adjusted my seating depth to .009 off the lands with .002 neck tension. the powder charge is the same at 43.5 gn producing an average velocity of 2608 fps. shooting very well.
New #2231 200gr SMK for F/TR
- Thread starter Quickoz
- Start date
yes, I have adjusted my seating depth to .009 off the lands with .002 neck tension. the powder charge is the same at 43.5 gn producing an average velocity of 2608 fps. shooting very well.
Down South
FTR Junkie
I have one here (198 gr Flatline bullet) that was sent to me, don't remember the OAL measurement off hand but it's a lot longer than the Berger 230 hybrid if I remember correctly. It's definatley a super long sleek looking bullet. I personally would run a 8 twist with a bullet that long, especially at .308 speeds.
Wondering for FTR In a .308 would an 8 twist give optimum stability with the 2231 sierra also allowing to shoot berger 20x and 185g hybrid or would an 8 twist be too fast for the latter 2 bullets.
Down South
FTR Junkie
Definately not neccessary with 185s, X bullet or 200 gr Sierra bullet but i'm sure it would work. I've shot and so have many others 155s with 10 twist barrels with great results so why wouldn't 8 twist work with longer heavier bullets? With that said, i'd go with a straight 9 twist barrel for those 3 bullets listed and not look back. I currently have a 30 inch 9 twist barrel on one of my FTR guns and it absolutely loves X bullets. I shot that load at the Texas LR Championship this year and it shot great.
Ned Ludd
Silver $$ Contributor
If you want to assess and compare twist rates for different bullets, all you need to do is plug in the bullet OALs/BCs with the appropriate atmospheric inputs here:
http://www.bergerbullets.com/twist-rate-calculator/
There are potential issues with running much faster-than-necessary twist rates, including effects on accuracy and possible jacket failure. The question here is whether an 8-twist is too fast at twist rate for some of the 185/200 gr 30 cal bullets currently being used in F-TR at the 2650+ fps velocities typically seen with 30"+ barrels. As Jade mentioned, 9-twist barrels seem to be working just fine for some of the 200 gr bullets currently available. I've also personally shot many bullets in the 190-ish gr weight range in commercial loads from a short (16") 8-twist 30 cal barrel at somewhat lower velocities without any issues, but that's not really the same thing. Only way to know for sure is to have an 8-twist pipe chambered and try it. If they shoot as well as from barrels with more optimal twist rates (9.5- to 10.5-twist range), you're GTG. If they don't work well, then you have an expensive tomato stake.
Having played around with several different 30 cal bullets this year in the 200-210 gr weight range, my take is that they're all close enough in terms of BC that none is going to enjoy any "quantum leap" advantage over the other. So if the BCs are all pretty close, what it really boils down to for me is how easy a particular bullet is to tune, how consistent the precision is, and how well you can handle the recoil. In my hands, the 200-20X bullet was probably the most consistent in terms of the first two considerations. They are pretty easy to tune and very consistent on the target. I personally find that pushing any 200 gr bullet out of an 18 lb F-TR rifle at 2650+ fps is about all the recoil I can manage. If I am not 100% on top of it at every second, I will start seeing vertical issues. YMMV.
There are several 30 cal bullet choices that fall into this particular class of bullets for F-TR (i.e. 200+ gr, G7 BCs > .315) that all have the potential to win. They're all close enough in BC that none is a huge advantage over the other in terms of wind deflection. So in the end, I think what it really boils down to is consistency on the target and how easy they are for an individual to tune in.
http://www.bergerbullets.com/twist-rate-calculator/
There are potential issues with running much faster-than-necessary twist rates, including effects on accuracy and possible jacket failure. The question here is whether an 8-twist is too fast at twist rate for some of the 185/200 gr 30 cal bullets currently being used in F-TR at the 2650+ fps velocities typically seen with 30"+ barrels. As Jade mentioned, 9-twist barrels seem to be working just fine for some of the 200 gr bullets currently available. I've also personally shot many bullets in the 190-ish gr weight range in commercial loads from a short (16") 8-twist 30 cal barrel at somewhat lower velocities without any issues, but that's not really the same thing. Only way to know for sure is to have an 8-twist pipe chambered and try it. If they shoot as well as from barrels with more optimal twist rates (9.5- to 10.5-twist range), you're GTG. If they don't work well, then you have an expensive tomato stake.
Having played around with several different 30 cal bullets this year in the 200-210 gr weight range, my take is that they're all close enough in terms of BC that none is going to enjoy any "quantum leap" advantage over the other. So if the BCs are all pretty close, what it really boils down to for me is how easy a particular bullet is to tune, how consistent the precision is, and how well you can handle the recoil. In my hands, the 200-20X bullet was probably the most consistent in terms of the first two considerations. They are pretty easy to tune and very consistent on the target. I personally find that pushing any 200 gr bullet out of an 18 lb F-TR rifle at 2650+ fps is about all the recoil I can manage. If I am not 100% on top of it at every second, I will start seeing vertical issues. YMMV.
There are several 30 cal bullet choices that fall into this particular class of bullets for F-TR (i.e. 200+ gr, G7 BCs > .315) that all have the potential to win. They're all close enough in BC that none is a huge advantage over the other in terms of wind deflection. So in the end, I think what it really boils down to is consistency on the target and how easy they are for an individual to tune in.
Bump
Ned Ludd
Silver $$ Contributor
That seems to be the consensus from a few people I've talked to. I was hoping others (not crickets, Wade
) might have something to add after Nationals. I'd have to think some folks were using them there. Anyone?Ned Ludd
Silver $$ Contributor
S
Same experience here, only I haven't tried the Sierra yet, hence my curiosity. In my hands, the 200.20X tunes in very easily, giving excellent precision. To me, it's simply hasn't been worth it to give that up for a slight to modest increase in BC. Nonetheless, I will still be forced to test out at least the next 4 to 6 new high BC 200 gr 30 cal bullet offerings that show up on the market...it's just my nature and I can't ever seem to break the pattern.
Same experience here, only I haven't tried the Sierra yet, hence my curiosity. In my hands, the 200.20X tunes in very easily, giving excellent precision. To me, it's simply hasn't been worth it to give that up for a slight to modest increase in BC. Nonetheless, I will still be forced to test out at least the next 4 to 6 new high BC 200 gr 30 cal bullet offerings that show up on the market...it's just my nature and I can't ever seem to break the pattern
.
My experience is the same.S
Same experience here, only I haven't tried the Sierra yet, hence my curiosity. In my hands, the 200.20X tunes in very easily, giving excellent precision. To me, it's simply hasn't been worth it to give that up for a slight to modest increase in BC. Nonetheless, I will still be forced to test out at least the next 4 to 6 new high BC 200 gr 30 cal bullet offerings that show up on the market...it's just my nature and I can't ever seem to break the pattern
Whats the thinking with why the high BC 200s are that much more finicky? Is it the age old tangent vs secant design or the faster twist needed to realise the full BC (I could see this making ultimate precision difficult but not causing "finicky") or maybe a combination of them both?
Ned Ludd
Silver $$ Contributor
I can imagine the cause(s) might be a few different things. Unfortunately, not all of those are easy to test if you don't own the right equipment.
I've used plenty of secant ogive bullets with very long noses that shot very well, so that wouldn't be my first guess. I've also used some fairly fast twist barrels (i.e. 8-twist in 30 cal) that worked just fine with some bullets, so that wouldn't be my first guess either.
Uniformity in jacket thickness and/or lead core might be part of the problem, possibly leading to slight imbalance issues. It could also be a design issue, if the CG is not suitably positioned, for example, or perhaps some undesirable contribution from the relatively short bearing surfaces that have been used. Balance issues such as these are unfortunately harder to confirm or deny without certain equipment, which I don't own.
Finally, there may also be some contribution from non-uniform points. At least a couple of the 30 cal high BC 200 gr bullets currently available actually come pointed from the manufacturer. So far my impression is that the points I have seen are not very uniform. I have recently been playing around with sorting and re-pointing some of these bullets in an attempt to determine whether that might result in a detectable improvement in precision, but have not reached any definitive conclusions as yet.
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