Home Forums Hunting & Shooting Ask The Gunwriters gain twist barrels

I am just wondering what advantages there are with a gain twist barrel? I remember people talking about them mabye 6 yrs ago but havent heard much since until seeing references here. If I were to build a 358 win or a 284win is there any advantage to a gain twist? Thanks guys.

Got 2 26 inch S/S RKS barrels chambered for 300 Win and 7 mm STW.Both barrel exceed a standard tube easly by 200 fps.Actually my 300 is right on par with a Roy.

To me it's like up-gunning without going to a larger round.Alot of guys with gain twist chambered rifles use odd lenghts because the barrel makes up the speed.

My barrels shoot extremely well.One thing I have noticed is they can be picky to load for but when you find the right load they are straight shooters.Always get a kick when I show up at the range and blow peoples minds with the speed.First thing they all ask is to see the case.Once they see no pressure they really start to asks questions.From what I have seen I will never go back to a standard twists again.If you were to go 284 Win you'd be close to a 7 Rem.

Next chore is to crony that STW again in the spring.Did it before but can't rember the final numbers.But it's alot quicker than my friends Sako 75 STW.I do mean alot faster too.

Would you be more specific?Who manufacturers gain twist barrels?I have never seen them offered from the "main" makers.What velocities are you achieving from your .300 Win.?What barrel length?Bullet weight,etc.?I might be interested in a gain twist.Pros and cons?
Thanks,
Jim <img src="/ubbthreads/images/graemlins/help.gif" alt="" />

Gain twist barrels have no purpose IMHO. If they added velocity, long range target shooters would use them. They don't. If they added accuracy, they would also be common on the target ranges. They aren't. If they could add 200 fps as one poster claimed, then Roy Weatherby would have used them starting in the 1940s. He didn't.

The theory, I suspect, is to start accelerating the bullet gently, or not deform its shape. Fine in the 1800s but now we have jacketed bullets and, since they start from 0 fps anyway, that's gentle enough for them.

Variable twist must, by definition, change the angle of the rifling relative to the bullet. You end up at the muzzle with grooves in the bullet wider than the lands of the rifling, a deformation which defeats the whole purpose. Actually, I suspect this leads to more powder gas blowing by the bullet, which reduces velocities.

It was a throwback to early smokeless/late black-powder idea's in controlling fouling!
It was a idea more used on the other side of the pond than here.
Never proven to add in velocity nor help in accuracy department either.
Nothing more than a "gimmic" now days.
Mike

Agree completely. I have one in 338 Jamison, which is the same capacity as the WSM cartridges, and I had several 338 WSM's with standard twist barrels. Mine was made by Apex in Flagstaff, AZ (don't know if they're still alive!!) and I saw very little difference in velocities achieved between the Jamison and the WSM's with the same barrel lengths. It's no more accurate either. I ordered it for all the hype and have reached EXACTLY the same conclusion for almost the same reasons you give. Good post!

I own four gain twist barrels by RKS ( Ron Smith , here in Alberta).
There are only two or three gain twist bvarrel smiths in North America from what I understand.

The gain seems to help when useing ULD bullets at high veloctiy, but it will not "add" velocity, that is a charicteristic of a particular barrel.
It does sem to help in keeping fouling down, but that too may be because of the super finish that Ron puts into his barrles.

I like them, but also have a stright 8" twist RKS , and it is no less accurate!

Cat

IIRC, the gain twist idea in sporting arms was introduced to reduce felt recoil on heavy rifles. This was typically used in the large double rifles of 10, 8 and 4 bore, that routinely kicked the stuffing out of people. Rifling has a very significant role in the recoil department. The idea is to gradually introduce spin rather than all at once, and the concept does work. This concept was taken to it�s final evolutionary step when Fosbery patented the concept of the Paradox gun. The Paradox was a smooth bore shotgun all the way until you got to the last 2 �� of barrel, then he introduced a shallow rifling. With this, you can shoot a 750 grain bullet at over 1300fps and still have your wits about you after firing. To my way of thinking, the Paradox gun concept is just pure genius.

The heavier the bullet, the better it works. In something like a .30-06 or smaller, I doubt the shooter would ever notice a difference. S&W has opted to use the gain twist concept in their .460 XVR revolver, and with how well that gun shoots, who could argue with their success?

In the accuracy department, there have been any number of variations on the basic rifling concept. Metford, Whitworth, Ballard, polygonal etc. Generally speaking (not including the ridiculous). If the barrel seals the gas and imparts adequate spin, then they all work about the same (for sporting use, benchrest is another story). The deciding factor is usually the overall quality of the barrel, and that�s what makes a difference. If you have a gain twist of outstanding quality, it will always outshoot a mediocre conventional barrel. In the velocity department, I doubt there would be much of a difference.

For small bore (less than .45 caliber) rifles, most of the advantages of a gain twist are more theoretical in nature than actual.

Hard to improve on that.

I"ve seen them run the course in match rifles for highpower. Worked just fine. Didn't do anything overly astounding. If it floats your boat thats fine, if not, you've not lost anything. Much like my continued use of moly in match ammo. Works for me but nothing extreme, I'm just too lazy to clean after every match....

Jeff

Mine haul azz period.There's another poster who has the same barrels that do the samething.You armchair quaterbacks make me laugh.You don't own one most likely but are experts.Next year you'll own one and it will be the cats azz.

Less bearing surface =less pressure=more powder=higher obtained velocity.Buddy with the powder blow by saying less vel is just another person who knows zip about these barrels talking just to hear himself..............so laffin.

S&W has opted to use the gain twist concept in their .460 XVR revolver, and with how well that gun shoots, who could argue with their success?

IIRC this was a measure (one of many in the .500 and .460 S&W's) to control the effects of rifling/bullet induced torque in these revolvers and wasn't intended as an accuracy or velocity enhancement. Among other things the first experimental .500's generated so much torque in the wrong direction that the barrel shrouds were coming unscrewed.

Just a bit of info for what it is worth.. IIRC the old Italian Carcano rifles were gain twisted too.

7
Have some 3 groove barrels here, not gain twisted, that net up close to 170 fps over and above standard barrels.... Not sure the Gain does it, but one can find advantages if they look long enough. So far the 3 groove issue has been repeatable to me, but I"ve only rebarreled them like 5-6 tubes so far.

JEff

Let's assume for a second that gain twist barrels are the best thing since sliced bread. Does it require a certain barrel length to work it's magic ? The 460 for example, would a short barrel snubby make the gain twist advantage negligible when compared to the conventional twist ?

I have a Pac-Nor "accident" that turned out to be a gain-twist. Curious, Big Chris sent the .257" barrel to Barrel-Scan Inc. and the chart says that the twist rate is completely linear from end to end; the twist rate is 1-11" at the breech and 1-9" at the muzzle.

Big Chris wanted to see how it shot, so I ended up with it.

Please be clear, this is a "sample of one." Having said that, this is the fastest, most untempramental, most accurate .25-'06 barrel I've ever shot.

The gain-twist Pac-Nor especially favors 100 Ballistics and runs them at warp-speed. I don't dare publish the top loads because they would without doubt be insafe in most other barrels. I'm not particularly pushing it; extraction is easy and cases last for-friggin'-ever.

I've prolly killed a dozen or so antelope with the barrel, plus a few little-bitty Alberta whitetail and mules <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />, and it's a one-shot/one-kill situation. I've even killed a bigger animal (again, with a single shot) that I dare not write about. Man, it slams furry creatures to the ground bang-flop.

No doubt, another identical barrel would be a slug, but mine is a true winner.

Steve

Thanks Steve
.Your results mirror mine.I'm the same as loads are concerned they are so much over it's dangerous to a common barrel.

Back in college I knew a fella who worked at Apex Barrel in Flagstaff, AZ.

This is how he explained the gain twist concept to me:

The initial engraving of a bullet with a slow twist rifling allowed more velocity at the same average pressure as compared with a load developed with conventional (faster initial twist) rifling. In addition, as the bullet travelled down the barrel and was progressively spun to a faster speed, the gain twist resulted in more area under the pressure curve as compared with conventional rifling with how it becomes "harder" for the bullet to leave the barrel, relatively speaking, thus resulting in a stabilized bullet with higher velocity at the same peak pressure.

All the gain twist does, essentially, is increase the area under the pressure curve, resulting in increased velocity compared to an equivalent load in a conventially rifled bore at the same peak pressure.

I never could afford a new barrel on my college budget at the time so I couldn't actually try one out.

BTW Apex barrels were cut rifled. I don't think it is possible to make a gain twist barrel with the button method.

Jason

Here's what Lilja barrels has to say.
www.riflebarrels.com/articles/barrel_making/details_of_accuracy.htm
Mike

Muzzle velocity is the integral of net force/mass * time. Net force is (the area of a cross-section of the bullet*pressure) - friction. Bullet mass is constant during acceleration. That's very well settled basic physics.

I have a hard time imagining where in that equation gain twist would make a difference in velocity. Where does the extra energy come from?