"Gain Twist" Rifling

[plumbum]

Or you could just buy a clean old Carcano?
I remember talking with a crusty old gunsmith (like 30 years ago) and he claimed he ordered a gain-twist barrel for a Mauser sporter in 8mm that he had built his hunting rifle with. I guess anything is possible, with money and time.

[slamfire1]

Slamfire1
Are those groups you posted at the various distances what you would consider to be good groups?

Lynn: My groups are good, they are good for my rifles and good for the day I was shooting them. The F class shooters I know are shooting well within my groups. And, these 270 Fusion bullets are pulled, and I think they shoot well for bullets. I showed the old Gun Club President my 30-06 groups at distance, and he said he was shooting inside of them with his 6mm or 6.5 mm cartridges, with ten shot groups within 1 MOA at distance. Well, that was better than what I am doing.

Lets start seeing your groups Lynn, and then we can ask you if you think they are good. And, lets see ten shot groups, not the three shot BS that the shooting community has been taught is the standard for accuracy and consistency.

[LynnJr]

Slamfire1
I wasn't trying to insult your hunting rifle groups. I saw a picture of a green gun I thought you said was a 308?

For your hunting rifle in 30-06 try a 190 SMK just touching the lands and 60 grains+ of RE22. It should cut those groups considerably.
For my groups I think you can get the results for most of the nationals online which are 30 shots lightgun and 60 shots heavygun.
If you can't find them I will take pictures and post them.
Nobody expects a hunting rifle with factory bullets to shoot small.

[smoothy8500]

Well, I did like this 600yd group although my eyes were starting to glaze over from the wall of text (and excess targets). It was your little line using a sling that actually caught my eye. Additionally, a fixed 10X scope instead of the 4X makes me seasick, I couldn't imagine a 24X scope.

I shot this string, prone with a sling. The way real men used to shoot

[Fjold]

I have a Bartlein gain twist barrel on my 6.5 x 284 that I've been shooting for 1248 rounds. It starts as a 9.25" twist and gradually speeds up to an 8" twist over the first 18" of the barrel and then stays at the 8" twist for the remainder of the remaining length of the 27" barrel.

With modern CNC machinery it easy to vary the speed of the cutter or button to change the twist rate of the grooves.

On a hammer forged barrel, you just have the cut the rifling plug in reverse. The hammers don't care what the shape of the rifling plug is, they just hammer the barrel around the form.

The theory of gain twist rifling is that the largest strain on a bullet and the peak pressure reached are when the bullet first engages the rifling and converts part of the kinetic energy from the forward motion into rotational energy of the spin. In a gain twist barrel, the transition of forward velocity to full rotational speed is done over a longer period of time so the maximum strain on the bullet and the peak pressure should be less. Theoretically this will cause a smaller loss of velocity during the conversion of kinetic energy to spin.

[bergmen]

On a hammer forged barrel, you just has the cut the rifling plug in reverse. The hammers don't care what the shape of the rifling plug is, they just hammer the barrel around the form.

I don't know how you could remove a gain twist mandrel from a hammer forged barrel.

Dan

[slamfire1]

Slamfire1
I wasn't trying to insult your hunting rifle groups. I saw a picture of a green gun I thought you said was a 308?

For your hunting rifle in 30-06 try a 190 SMK just touching the lands and 60 grains+ of RE22. It should cut those groups considerably.
For my groups I think you can get the results for most of the nationals online which are 30 shots lightgun and 60 shots heavygun.
If you can't find them I will take pictures and post them.
Nobody expects a hunting rifle with factory bullets to shoot small.

That's nice. Would love to see you post target groups related to a topic. Not degrading the hunting rifle groups, that's nice. My 308 Win M70 target rifle, sure, would it not be nice if they were all in one hole at 300 yards, instead of 4.5 inches. But, they were all in the ten ring of the standard NRA target.

One of these days I am going to CMP Talladega and try my 190 SMK's in my 30-06 target rifle. I am curious to see if bumping the velocity up from that of my 308 Win rifle will keep the bullet from tumbling at 600 yards. And if I post them, I expect you to come in and also denigrate them.

What about the groups from your 30-06 hunting rifle. I would love to see those.

[200Apples]

I think it was Jeff Cooper that once said about the latest claims by those riflemen who owned some very accurate rifles, "If that rifle were just half as accurate as it is, it would still be twice as accurate as it need be."




Thank you gentlemen for this discussion on gain twist. Learned something new today.

[slamfire1]

Well, I did like this 600yd group although my eyes were starting to glaze over from the wall of text (and excess targets). It was your little line using a sling that actually caught my eye. Additionally, a fixed 10X scope instead of the 4X makes me seasick, I couldn't imagine a 24X scope.

I have been a sling shooter for more than three decades now, and I am proud of that skill. However, I got old. I can't take the 90 degree heat and physical exertion required to pull targets, such as I was doing at Camp Perry. Guys would have heat stroke and collapse on the firing line. I used to drink gallons of water during the day at the Nationals. Not only did highpower shooters shoot in gales, they shot in the rain. It could be horrible. But when you are young and hard core, coming back to the hut covered in grass and mud was sort of a macho thing.

I shoot Smallbore prone now, we shoot in the shade, and we don't pull targets. I am sad that fewer and fewer sling shooters are around. But the good ones are amazing.

These are 50 yard targets of two different National Champions at a Regional. I walked down from my target and took a picture of these, all fired on the same relay. These guys are shooting prone with a sling, and iron sights.





there are five shots per bull, twenty shots per record in the bottom targets, and the sighting bull is allowed as many shots as wanted. You can understand why smallbore prone had to go away from the ten shot per bull target, that was around in the late 50's. These guys are making a hole with five shots, and it is hard enough for the scorers to determine that there are five shots in each.

Occasionally I shot as well as these guys, the good ones do it all the time.

[bergmen]

There is even a revolver with gain twist rifling:

https://www.americanrifleman.org/articles/2020/2/26/smith-wesson-460xvr-revolver-review/

Dan

[LynnJr]

Slamfire1
How is this?
Yes it's a 1000 yards so 400 yards further and yes its 30 shots not 3 so many more shots fired.
Did I do okay?

[LynnJr]

I don't know how you could remove a gain twist mandrel from a hammer forged barrel.

Dan

Good point

[mtenenhaus]

you guys are awesome, thanks for sharing the photos....i've got a lot to learn

[M1NM]

Hammer or regular rifling would work you just need to vary the speed of the rifling tool as it goes through the barrel. In WWII my dad got a bunch of war bonds for creating and building the tooling to rifle a bunch of carbine barrels in one pass.

[Garand Hunter]

The old 6.5 carcano rifles had gain twist rifling, but the Mannlicher type action was just about one cut above junk, in my not so humble point of view. Once upon a loooong ago time I read a old story about the Italian solders throwing these rifles off the road going over Brenner Pass as they fled back to Italy. Anyone remember the saying " dropped only once " ? Also that rifle was reportedly used by Oswald on John kennedy.

Psalm 1