Anyone know the percentage of F Class and benchrest shooters who use Gain Twist barrels? The concept seems to make sense to lower pressures, but does it improve accuracy?

none

I would change that answer to very, very, few. Not many barrel makers produce them and not many competitive BR or "F" class shooters care to experiment too much. I have one 308 barrel on a HBR which gains from 16 twist to 13.5 and it is one of the best I have had on a hunter rifle. I have one 6.5 which is also as good as any barrel I have had. The thing is, while a gain twist may work as well, it isn't going to work any better. Also, while there is no evidence that a gain twist will reduce pressures, there is no evidence that it will not. Velocities do seem to be a little better but again, I don't have enough data to say for sure. I prefer a moderate gain; say 20% or so. I will say, the only reason I have used the gain twists is because a friend of mine makes them. He cuts a very good barrel, whether uniform or gain twist.
Some makers have experimented with a very slight gain (start at 12.5 and finish at 12 sort of thing) but I've never heard anything positive or negative about the concept. WH

Greydog! Thanks for sharing what you know.
I don't know much about them at all but wondered if they were in use at all in competitive shooting. Sounds like the answer is no. It seems intuitive that pressure would be lower, but I'm not so sure. I would tend to guess that the pressure spike occurs when the bullet has to enter the lands and the bullet is stationary. Friction and initiation of movement of a mass. Once moving and accelerating, that pressure may be lower, but it's likely not the peak. JMO...

In the old days, Harry Pope was an advocate for the gain twist and his barrels did very well. Chances are, his barrels did very well because they were very well made; gain twist or no.
GT barrels are still well thought of in the Scheutzen matches, using lead bullets. I have seen some very good 22LR rifles built using gain twist barrels but, again, no evidence they are any better but do seem to be just as good. GD

I know of no gain twist barrels being used by any of the top shooters in 22 rimfire benchrest. The fad barrel now in that game are MI or minimally invasive rifling. Just a fancy way of saying shallow grooved. A few years back folks experimented with slow twist barrels on the very edge of stability from 1/17.5" to 1/19". Some worked well in warm weather but when it got cold they would keyhole. I in 16 or 1 in 16.5 twists are pretty much the std.. Folks in that game will use everything from 2 to 8 groove barrels. My best barrels were a Broughton 5R 1/16" sporter barrel and a Rock Creek 5 groove 1/16" both hand taper-lapped. I did have a Shilen Ratchet barrel in 1/16" that was almost as good as the Rock Creek..

These are used in RF barrels in the schutzen rifles where they also have a BR class. These particular barrels are well regarded in these circles. Interestingly, the same maker also swears the left hand twist barrels shoot a bit better than right hand twist (he makes both).
Speaking of the MI rifling, Pope claimed a barrel could be rifled with coarse emery and it would perform well but not for long. GD

How about barrel life with extreme velocity? Say 6.5/300 Wby. mag. starting at 10" gaining to 8"?

With ELR shooting the different spin direction makes them shoot to the right vs. the left... freaky deekie until you’ve seen it 2-3 times, even then.

But if we’re talking freaky... shooting east then west at past a grand changes your POI elevation... I know the earth is spinning but WTH !!!
Again until you see it under controlled conditions it’s folk lore.


For “twist gain” - remember the crowd you are talking about is trying EVERYTHING to get an edge on the other guy..
If it’s right, the entire crowd ends up there.
For me it’s is it repeatable, and proven under controlled conditions - which costs me a frigg’n huge amount of money because I experiment.. but the bug holes are worth it.

I don't think the purpose is so much extending barrel life as it is preventing bullets from blowing up mid flight.

gain twist bartleins are used fairly often in short range benchrest

I believe the gain twist Bartleins are a very slight gain. I order gain twist barrels with a moderate gain (ie. 15 to 12) but I have one, a 6.5 on a hunting rifle, which starts at 24 and finishes at 8. Whether or not there is any measurable benefit in any performance aspect, I can't honestly say. Ultimately, a good barrel is a good barrel, regardless of rifling configuration or rate of twist. GD