I talked with a nice and helpful fellow at Bartlein when I ordered a gain twist barrel in .338 and he recommended a very limited gain in the twist on the order of a gain of one to two inches over the length of the barrel.
It had always seemed to me that quite a bit of gain would be ideal, i.e., for a 6mm barrel having a 7.5" twist at the muzzle but starting the bullet at a very easy twist rate of say 1 in 14 inches. ( I hope I am stating this clearly.)
Any opinions or experiences are appreciated.

My thoughts: Drastically changing the twist from the throat to the muzzle is going to drastically change the geometry (pitch angle) of the rifling, which is going to dramatically mangle the surface of the bullet. Seems like it would hinder accuracy more than aid it at a certain point.

I Don't think a gain twist is worth doing. It's going to increase the rifling distortion which is going to effect BC

I am not convinced a gain twist barrel is any benefit. If you think about it, a bullet starts from zero as it starts into the rifling then gains speed thus rate of rotation as it goes through. Altering the twist requires that the engraving on the bullet also changes. I have no data to back my conjecture but I have never seen any data to support the idea.

Experiments have proven a gain twist does NOT reduce initial, peak pressures much, if at all--which is the most common supposed benefit. Instead the early pressure peak is caused by the bullet hitting the rifling, which requires considerable force to engrave the bullet.

Another point: If gain-twist rifling had substantial advantages over standard rifling, top competitive shooters (whether short-range benchrest or long-range target) would be using them. I don't know of any who do, and I know some top shooters in several disciplines.

The Germans believed it had some applications for artillery in WWII but even there I don't think it is used much. I know some rifling operations don't produce a true twist but don't think any change the length of the bore unless something is set up wrong. A mild gain twist of an inch or less should not hurt accuracy. But it is doubtful of any other gains so why do it?

Gain twist has a place but I rather think not with modern arms. If shooting large soft alloy lead bullets a measured acceleration allows the bullet to achieve sufficient rpm to avoid stripping. It does serve the objective well. Likewise if shooting very heavy projectiles using drive bands a gain twist would be beneficial. Apparently the Navy thought so anyway as some of the old ship guns had gain twist....and a lot of grooves.



Their max weight for a 16" shell was 2,700 pounds with MV of 2500 to 2690 fps. I have seen pictures of this where it is quite obvious they had gain twist but cannot find any at present.

"Kills on both ends."

My preference is for a moderate gain (25% or so) but I have a couple which gain a lot (24 to 8 in one 6.5mm, 30 to 12 in a 25) and both shoot very well. The truth is though, I think the gain twist is a novelty as much as anything. The only reason I have them is because the maker likes making them because Harry Pope made them that way! GD

Yep--and Pope liked them for lead bullets, due to not deforming bullets as much during their initial engraving. But lead bullets are also more malleable than jacketed bullets, thus more resistant to meaningful deformation.

Pope was a very interesting guy, far more educated in basic physical principles, due to going to M.I.T. But like a lot of visionaries, he had a hard time making a living....

Rock Creek barrels are gain twisted. They have been for years even before the advertised as such. I have had exceptional luck with their barrels too.

Come on, guys. It's gotta be good - it was used in Mannlicher-Carcanos.

A slight gain twist seems to be popular with prs shooters but whether there is any advantages remains unclear.

Am sure, knowing the tendencies of competitive shooters, that if somebody won a major PRS match with a gain-twist barrel, then a bunch of others would be using them.

But as I mentioned earlier, I know a few very good competitive shooters. On is a local friend who set the 1000-yard benchrest record for the smallest 10-shot group at 1000 yards (under 3 inches both times), and he does not shoot gain-twist barrels.

Another set a world record in "short range" benchrest shooting maybe 3-4 years ago. Same deal.

As far as I know David Tubb does not use gain-twist barrels, but could be wrong. However, if he does my searches on his website for various kinds of info has not found that.

Hello Mule Deer and All

I am curious if there might be an advantage here where someone just needs a faster twist to stabilize a heavier/longer bullet such as a 150 gr .270 and then go to a 170 gr spitzer.
What does every think about this idea?

Also, what does everyone think about of just screwing on an extension giving a faster twist to be able to stabilize longer bullets. This might be a off the wall question...BUT STILL!

Glenn

I think if you want to shoot a longer bullet that won't be stabilized in a standard twist, you have a faster-twist barrel chambered for your cartridge and screw it onto your action. You can't speed up a twist that already exists by twisting the end of the barrel or something.

I imagine it is possible to create a gain-twisted barrel extension, but I imagine the results would suck so much that it would be better to just get a new barrel and swap between them, which is pretty simple, actually. You could align the rifling in the gain-twisted extension, but pressure and vibration and the need to have the thing stay tight would mean that it would likely eventually get out of alignment.

I think that would have all the questions of an (abrupt) gain twist, along with the machining difficulties of precisely lining up two bores and two sets of threads.

There is a lot of talk about deformation of bullets by gain twist barrels and the truth is, all rifling deforms bullets. A recovered bullet, fired from a gain twist barrel, is identifiable because the groves in the bullet are slightly wider at each end. This is more noticeable if the rate of gain is significant. In the end, as I've said before, gain twist barrel shoot neither better nor worse than a uniform twist barrel if the quality in other aspects is equal. Just like the number of grooves or rifling configuration, it is a novelty (although five groove barrels can be problematic when chambering).
One area where the gain twist does have a following is in the Shuetzen competitions. Of course, they are shooting lead bullets. GD

A few years ago several of the benchrest shooters were using gaintwist barrel's but the gain was very slight. If I recall one of my friends was shooting a 1-14.25"to 1-13.75" at the muzzle, they seemed to work quite well but I don't know of anyone still using one

Do you know what the goal was for such a small increase in twist? Does it keep pressure up better going down the bore or something because of slight engraving change in the bullet? I'm just guessing.

To be honest I truly don't know......Benchrest shooters are a tinkering bunch that will try anything to get even the slightest advantage over the competition

With Rock Creek making gain rifling twist barrels exclusively and being the 5th most popular barrel In PRS I would assume that they have been successful and are popular amongst precision shooter. .

Bartlein being the one of the most reputable barrel makers produces their T style rifling. If there were any disadvantages, I’m sure they would have abandoned the practice long ago. Bartlein is the number one barrel on the prs circuit btw.

Tony Boyer won the 100 and 200 yard bench rest nationals(?) with a gain twist.

They are more popular and more common than one would think.

Tony used a gain twist when? Butch Lambert has one also. Listen to Mule Deer, very few BR shooters use them, but they are popular with the lead bullet fellers.
Frank Green at Bartlein made mine many years ago, bit I've never shot it.

I’ve been listening to MuleDeer for many many years as well as you and many others on many different boards btw. T style rifling or gain twists are definitely not a rarity among people who shoot competitively across different disciplines, not just benchrest. As I mentioned, if Bartlein thought there were any disadvantages to gain twists they would have abandoned the practice long ago rather than risk their reputation. ( This goes for other barrel makers)

I’d post a link or links(?) about Tony’s win but never bothered to learn how to do that. I think his barrel had a relatively small gain twist.

Google it, you’ll find lots of info.

akaSawDoctor,

Thanks for the info. Will be doing more research--not just Internet but personally....

I am good friends with one of the best BR smiths in the world and a BR HoF shooter in his own right and he tells me that a slight gain is a great idea.Usually a gain of less than 1/2 inch over the length of the barrel

I shoot 1000 yard BR at Williamsport and was able to shoot my way into the HOF and also set the current 6 match group agg record using a Bartlein gain twist barrel. I'm also currently using a straight 4 groove Kreiger (non gain) and it is one of the best barrels i've ever owned and I've owned a few. Go figure. . . .

Did the smith say why it is a great idea? I'd really like to begin to understand the physics and internal ballistics of a slight gain twist that would make it of benefit for accuracy.

Gain twist barrels have been around for many decades. After all these years without adoption by the competitive shooting community, if (with "if" being an important word, here) there are any advantages to a gain twist barrel, those advantages are so small as to be swallowed up by the myriad other factors that affect how well a barrel shoots. In other words, any possible benefits are down in the noise, at best.

in short range it is a stability thing. bullets' are shot in a twist that results on the bullet being in the ragged edge of stability.
so to "help" a 14 twist a little extra is added such as 13.75 gain.

Then why not just twist the thing 13.75 from the get go?

maybe because increasing bullet friction/drag further down the barrel is a good thing???

maybe because opening up the grooves in the bullet created by the rifling and allowing gases to bypass helps!!!!

maybe because creating stress between the jacket and core helps them to separate on impact!!!


all jesting aside, I too would like to know the reason it 'works' over just the normal bbl length consistent twist..............

Congrats on your good shooting!

I guess what those two barrels prove is that a good barrel is a good barrel. :-)

as he said;
I guess what those two barrels prove is that a good barrel is a good barrel. :-)

it is very true. and not easy to grasp if you dont shoot a lot and you are searching for that SPECIAL barrel

The Germans in WWII found some benefits in gain twist artillery barrels. They were trying to shoot across the English channel. I did not read the studies and this was mentioned somewhere else. They were also experimenting with Sabots and tapered barrel artillery projectiles with flanges that folded back as the barrel diameter decreased.

One advantage to the gain twist even a slight gain is it insures the barrel doesn't have less twist at the muzzle. This situation was more common when the rifling equipment was less precise.

I know of one barrel which was made with a reducing twist and, apparently shot OK. I don't know what the rate of loss was; I don't think it was very great. GD