Gain twist question

[Johnch]

A coworker ask me about loading and shooting cast out of his dads war bring home 6.5 x 55 .
I could not find a name on it that I could make out , but it is difently high grade .
But some time in the past they drilled holes for bases in the action , ignoring the barrel mount .

When I looked in the bore I saw it was gain twist , with sharp rifling that looks new .
He gave me a Lyman 266673 , 150 gr gc ( I think ) to cast him a few .
He even had 1/2 box of gc , brass and a set of dies .
I have a sizer

Now I have never messed with a gain twist or 6.5 x 55 .

I figured I would tell him 14 gr of 2400 for a start load .

How do gain twist and cast bullets get along ?

He is looking for minuite of clay target at 50 yds to start his boys shooting CF , I think he plans on them jioning him deer hunting this fall .

What accurey shoud he be able to get ??
Without lots of messing around .

Johnch

[Buckshot]

................Gaintwist has no bad effect on cast lead boolits. Gaintwist has been around for a couple hundred years and Harry Pope was an admirer of it, so who's to argue with him? The point is, it has no magic effect on cast boolits to make them shoot any better then a barrel with 'regular' type rifling of comparable quality.

I see in the Fouling Shot magazine that every now and then someone lists shooting a gaintwist barrel, but it is rare. My personal opinion is that it has no benefit, even though the theory behind it sure seems like it would.

I would just load the 6.5 you have to produce no more then 1650 fps and you should be good to go. You can try a higher velocity just to see how far you can go before you lose consistant accuracy. In my testing it appears that you do not need highly alloyed slugs (like linotype) and can do well with lead hardnesses of 14 to 18 bhn.

I have a question about the cartridge though, if it is in fact a vet bringback. It could be the Swede 6.5x55 cartridge in an aftermarket barrel, and have a gaintwist bore. But could it possibly be a 6.5x52 Carcano? They came issued with gaintwist barrels (in 2 models only. Not ALL Carc 6.5's were gaintwist).

Anyway, there are quite a few common cast boolit powders that do well in the fast twist 6.5's so long as you mind the velocity.

.................Buckshot

[mooman76]

Forgive my ignorance but, what is a gaintwist barrel?

[StarMetal]

It's a rifling that starts out at a slow rate of twist and as it progresses towards the muzzle it becomes a faster (gains) of twist. It does this in a smooth transition, no abrupt chance.

Joe

[Johnch]

Only thing I know is
1 it is a 6.5 x 55 , I checked by fireforming a 6.5 x 55 case with Bullseye and COW
Then I compaired the fireformed case to the specs in a reloading manual

2 his dad was somewere in Germany at the end of WW2 .


3 I first though it had to be a 96 , but I checked it out .
The front ring is the right size
It has the safty extra lug and a bolt from one of my FN locks up nice and tight .

Johnch

[mooman76]

I've heard of those (gain twist) and even thought about it before I heard about it. I would think logicly it would work better but things don't always work the way you think!

[Leftoverdj]

Treat it like a Swede and put 10.5 grains of Unique behind those bullets. Time enough to worry about the niceties after you've tried the obvious.

[buck1]

""My personal opinion is that it has no benefit, even though the theory behind it sure seems like it would. ""
Me too!! But it does "sound "good....Buck

[Bent Ramrod]

The gain twist was really in its element in the old cap-and-ball revolvers and the picket bullet rifles where the driving surface that engaged the rifling was a thin ring, either on the circumference of the spherical ball or at the rear of the conical picket bullet. A long bullet with lots of shank would tend to have the front turning faster than the rear, maybe opening up the grooves in the bullet made by the rifling and allowing some gas leakage.

Would the rifle in question here do better with a long, bore-riding nose and a relatively short driving surface, or a Loverin-type bullet that is mostly shank? Some experimentation on this line would be interesting.

[DLCTEX]

Seems I read that the s&w 500 or the more recent 460? has gain twist rifling to prevent stripping because of the quick start of the boolit under the high pressure.

[475/480]

Seems I read that the s&w 500 or the more recent 460? has gain twist rifling to prevent stripping because of the quick start of the boolit under the high pressure.

The SW 460 has gain twist.

Sean