Twist rate for .32SWL for 50m

[BobGee]

I have a colleague who is getting a replacement, locally made (in Australia) barrel for an older Pardini .32SWL. Although he currently shoots just ISSF, I suggested to him that it might be possible to get a barrel with a higher twist rate than the usual 1:18” or so for better performance at 50m should be ever want to shoot that. Two questions emerge:
1. What is the best twist rate for .32SWL for 50m accuracy (1:10”, 12”, 14”), and
2. What, if any, are the downsides of a higher twist rate than normal?
Bob

[Isabel1130]

Hopefully Dave Wilson will chime in here. He actually makes Pardini barrels. But, as I understand it, a different twist rate is only one part of the equation. The other larger part will be the diameter of the barrel, and the bullets you have available to use in it. If the bullet doesn’t fit the barrel correctly, it won’t engage the lans and grooves correctly to establish the necessary spin. Bullet hardness and a perfect swaged shape will also contribute to whether the gun will shoot at 50 meters.

[fc60]

Greetings,

From all of my testing, the BULLET is the key factor for accuracy.

One can get sub 50mm groups at 50 yards (45.72M) with a factory 1:450mm (1:18) twist barrel in good condition. Never actually tried 50M.

Here, in the USA, quality 32 HBWC bullets are quite rare. The best offering is the Speer 98 grain HBWC. Sadly, they do not shoot well in factory Pardini barrels.

This presents an opportunity to source a barrel blank of 0.311" and a twist of 1:10 to 1:14. Barrels made with these blanks will shoot the Speer bullet as received. (One still needs to cull out the ones with obvious nicks and dings on the base.)

Try to source a surplus 303 British barrel in excellent condition.

Something else to be aware of. Pardini barrels of current manufacture are hardened to 38-42HRC. Most barrel blanks are 32HRC, or less.

There are other ways to improve the accuracy. Swaging is one such method.

Cheers,

Dave

[BobGee]

Thanks Isabel and Dave, i shall pass on your very valuable advice.

Bob

[Leon]

" The best offering is the Speer 98 grain HBWC. Sadly, they do not shoot well in factory Pardini barrels."

Oh, I shoot Speer 98g HBWC in .314 in my Pardini exclusively, and have no accuracy issues...They group very, very well indeed..

[BobGee]

" The best offering is the Speer 98 grain HBWC. Sadly, they do not shoot well in factory Pardini barrels."

Oh, I shoot Speer 98g HBWC in .314 in my Pardini exclusively, and have no accuracy issues...They group very, very well indeed..

At 50m?

Bob

[Isabel1130]

That is the question, isn’t it? As was explained to me, by some people who know far more about ballistics than I do, the European guns designed for 25 meter shooting, tend to destabilize somewhere around the 35 meter mark. After that, your groups tend to look like the flare end of a Trombone. Fine out to 25 meters, and after that, chaos. Tumbling bullets are easy to spot on the paper. I have shot next to a few people shooting 38 wadcutters, and 32 Wadcutters. It can often be very ugly at the fifty yard line, especially in the wind.

In the Bullseye discipline in the US, the test for ammo and guns is always the fifty yard line. Most guns shoot well enough at the 25.

[JamesHH]

Try to source a surplus 303 British barrel in excellent condition.

Do they exist?

Why would anyone ever want to shoot 50m with a Pardini .32 in Australia?

I made a barrel for my 7.62x29 Toz49 from a Sprinter 1:10 .303 blank which shoots great at 25m, someone I know used a piece of it to make a 5" .32 GSP barrel which apparently works well at 50m.

My old S+W model 16 with a 1:18 twist worked fine at 50m with Lee 90gr Tumble lube semi-wadcutters - it was terrible with HBWC.

Short answer - I don't know, good luck.

[BobGee]

Why would anyone ever want to shoot 50m with a Pardini .32 in Australia?

My colleague is getting a new barrel made anyway so I thought there might be an opportunity for him to get one with a higher twist rate should he ever wish to shoot out to 50m - at no cost to him. No one seems to have suggested any disadvantage to having the higher twist rate.

Bob

[JamesHH]

The likelihood of anyone wanting to shoot 50m with a pardini in australia is about nil, apart from odd club fun match.
GSPs yes as people use them for our obscure service match.

Its about as likely as anyone wanting to shoot 100m with a bullseye pistol in the US I guess. Should bullseye shooters go to trouble to select their barrels for that eventuality? Probably not, as long as it works at 50 yards no-one cares after that.

Whether there are advantages, or disadvantages, to getting a faster twist for 25m I don't know.
My Toz will shoot pretty well any bullet and any load very accurately right down to 600fps with a 1:10 barrel so maybe.
Not sure how twist affects recoil, I'd guess the faster the twist the sharper the recoil.
Is there a greater risk of skirt separation?

[Mike M.]

On the other hand, a gun that will shoot well at 100 yards/meters will shoot well at shorter distances.

[BobGee]

On the other hand, a gun that will shoot well at 100 yards/meters will shoot well at shorter distances.

My point exactly, though only thinking of 50m.

Bob

[BobGee]

Not sure how twist affects recoil, I'd guess the faster the twist the sharper the recoil.
Is there a greater risk of skirt separation?

Now, I think a potential increase in recoil might be a good point but if one is able to shoot a TOZ49 with a 1:10 rate accurately, perhaps not an issue

Same argument for skirt separation, which I also believe is now a thing of the past as bullet makers have thickened them up.

Bob

[David M]

The .32 sw Long at 50yds brings up some problems.
Firstly, are you shooting a revolver or auto.
Revolvers can be loaded up in velocity and allow lots of bullet types.
All .32 auto's are blowback type, similar to .22 and are limited in loading and velocity.
You normally don't see locked barrel types until .38/9mm.
The skirt seperation problem is easy fixed using cast solid wadcutters.
For Australian Unrestricted Service I have used a Walther GSP, Hammerli 280 and best of all a Unique DES 32.
Best results at 50yd/m are the .38 Special Manurhin match or Sig/Hammerli P210-5LS in 9mm.

[JamesHH]

On the other hand, a gun that will shoot well at 100 yards/meters will shoot well at shorter distances.

My point exactly, though only thinking of 50m.

Bob

So do Bullseye shooters test their guns at 100m to be sure they shoot well at 50?

[mister G]

Seems we're bordering on silliness now. To the best of my memory, there are no pistol marksmanship competitions at distances of more than 50 meters.

Both the 98 grain HBWC and the BBWCs can be made to give X-ring hits with the right combination of powder, gun, barrel, twist rate, et cetera at 50 ft, 25 ft/meters, up to 50 yard/meters. Lot of testing required to get this to happen and the experts are here in this forum.

A Ransom Rest is a helpful addition.

[northpaw]

At paper targets bullet holes from wadcutters often appers slightly out of roundness, indicating yawing, and some instability, i think.

The bad ballistic coefficient of wadcutters will reduce velocity markedly to 50 m. But rotation, angular velocity, will not be reduced much. Hence, may the wadcutters become over-stabilized? What may the effect of overstabilization be?
Hope someone with knowledge may put light to that topic.

[JamesHH]

Well, I've barely had even a hint of yawing from my 1:10 twist Toz even when the bullet is so slow the paper is tearing, so I don't think its over-stabilisation.

This picture is two Toz tested at the same time, bottom loads are BNWC



Part of the problem may be that not all HBWC are designed or made equal.

Some time I'm going to load it with round ball and see what groups it gives.

[BobGee]

Well, I've barely had even a hint of yawing from my 1:10 twist Toz even when the bullet is so slow the paper is tearing, so I don't think its over-stabilisation.

This picture is two Toz tested at the same time, bottom loads are BNWC

Part of the problem may be that not all HBWC are designed or made equal.

Some time I'm going to load it with round ball and see what groups it gives.

At what range were these shot, James?

Bob

[JamesHH]

25m, pretty sure it was off a sandbag, most people get some yawing at 25m with .32 or .38 HBWC

Maybe I'll try it at 50 just to be sure it works at 25.

To the ransom rest!