PPC revolver with tight barrel and wide throats. What should I do?

I want to start pretending to be a cop from the 1920s and I just lucked into a Smith and Wesson 581 that was configured for PPC competition. It has a very nice trigger job, a custom slab sided barrel, detachable under-lug, and a classic Aristocrat three position sight.
Slugging the barrel shows that the groove diameter is a tight 0.3564" - 0.3566" and the cylinders all slug to 0.3600". The Ingot to Target Guide says to size bullets to the size of the cylinder throats, but this is a difference of four thousandths of an inch. Because this is such a customized revolver I have to believe this difference was not a mistake.

Any old school PPC-ers know what is going on here?

Will shoot wadcutters GREAT! Factory Remington and Winchester HBWC bullets are .360 so you want the throats that size to fit bullets without deformation. Best guns used tight 9mm barrels with fast 1:10" twist. Key is reducing forcing cone angle to six degrees included angle. You have a winner! Cast will shoot in it too and fast twist gun is accurate out to 100 yards with correct loads. Bill Duncan wrote several articles in The Fouling Shot testing his Bob Day PPC gun at 100 yards. Impressive.

FYI Colt Pythons had .359-.360 throats and .354-.355 barrels. It was a thing to install Python barrels on S&Ws.

I have a couple molds that I got in trades that are wad cutters intended for 38s. One is a Lee intended for use with Alox, so it has those mini lube grooves. The other one is an RCBS with traditional lube grooves and a button top. Both are 148 grain.

Do you have any load recommendations?

Nearly every PPC revolver guy uses wad cutters. I would start at .357 and see how they load. .001" over is a typical start.


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My wadcutter revolver was built on a S&W model 66 for NRA Bullseye Match (now called Precision Match I think ) we shot on an indoor range at 75 feet (25 yards) and its most favorite and accurate load with 148 gr. cast solid base or swaged hollow base boolits was :
1.) 2.7 grains Bullseye powder . It's next favorite load is
2.) 2.6 grains Red Dot .

Hope this helps you get started .
Nothing more soul-satisfying than a group where all the holes overlap each other !
Gary

The Fouling Shot No. 276 of March-April 2022 starting on p. 10 Bill Duncan compares four different cast wadcutters fired from his scoped Bob Day PPC gun at 100 yards. While my favorite Saeco #348 groups consistently under 2 inches at 50 yards, it did not cut the mustard at 100 yards. NOE 360-148 WC modified to an HBWC by Erik Ohlen at 0.632" length and .360 diameter loaded to 810 fps using Redding Profile Crimp gave consistent 100- yard groups of 3-4".

Lyman 358063 cast 1 to 30 tin-lead at 149 grains, being 0.579" long as cast at .358 diameter loaded to 850 fps was...

"...not very good, groups around 12 inches. I have never had success using bullets as small as .358 in a PPC revolver."

Ohaus 38-140W is another which didn't do very well. Inconsistent groups smallest 2.85" largest over 8 inches...

FS #271 shows effect of velocity variation on vertical dispersion at 100 yards.
FS #258 has experiments fired at 200 yards.

I have an old S&W 586 that I used to shoot PPC with that has very similar dimensions. It is fantastically accurate and does NOT lead with my standard 2.7 grs. BE/ 148 WC.

You are much better off that if the dimensions were reversed, with the chambers being .355" and the barrel at .360".

Hmmm.. My (avatar) Uberti Old West model in 45 Colt has .4565" throats and .451" barrel. I use 454190 cast soft enough to scratch, sized .456" with SPG lube and it is a fly's worst nightmare at 10yds and never have to clean it. It leaves the bore seasoned with powder and lube residue which provides lube to the front part of the boolit, Maybe I should try some HBWC just for grins?

Thanks for all the info, everyone. It cleared things up.

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Originally Posted by DougGuy

Hmmm.. My (avatar) Uberti Old West model in 45 Colt has .4565" throats and .451" barrel. I use 454190 cast soft enough to scratch, sized .456" with SPG lube and it is a fly's worst nightmare at 10yds and never have to clean it. It leaves the bore seasoned with powder and lube residue which provides lube to the front part of the boolit, Maybe I should try some HBWC just for grins?

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With a gun spec'd like that, I'd look hard at MP's clone of the .455 Webley MKIV bullet:

Attachment 313516

Attachment 313517

I don't have a lot to contribute on the PPC game, but I can say that for the low intensity loads under discussion, that soft alloys and hollow bases have their own brand of magic. I use the above bullet plus the MP clone of the WWI regulation .455 MKII bullet in my Webley MKVI. These guns are known for the dimensional oddity of throats that are smaller than groove diameter. You would expect them to lead up like crazy, but with the HB's it is a complete non-issue - even with those bullets just tumble lubed instead of the size-lube they're intended for.

I'm just hypothesizing here, but my guess would be in a gun like the OP's and DougGuy's Uberti, a hollow base bullet will help achieve the "Fit Is King" scenario we all preach - not just in making a good bore seal, but probably also in making sure the bullet gets a concentric entry into the forcing cone.

I can only echo the posts affirming the excellence of your gun as a PPC or Bullseye gun with midrange wadcutters. That gun sounds like it was put together by someone who knew what he was doing.

Back in the late 70's and early 80's when I was putting money in the pot for the winners, everybody used 2.7 grains of Bullseye, 2.8 grains of Red-Dot or 3.0-3.1 grains of WW231. Usually with cast Button nose 148 grain boolits for practice and Remington factory midrange wadcutters for the match. (The really good guys used factory Remington Ammo for the matches, but 7.95 a box was too rich for my wallet.) I had a Bill Davis gun, with a 1 inch, round, BBL, Bomar rib, and one of the Davis actions that were smooth as butter. I wish I hadn't had to part with it when I did, but I had a second child to pay for, and the insurance deductible was pretty stiff.

I've pulled (inertia) bullets from Old Remington and Federal 38 SPL WCs, from back in the hay day of PPC competition, which were reputed to be the most accurate ammo. Back in the day most of the winners used them at least at the 50 yards line. The soft swaged WCs ran .356 +/-. I recently loaded some Remington swaged WCs in Winchester brass which had been expanded with a longer .356 expander. Yup, after pulling the bullets had been sized down to .356 from .360. A recent machine rest test of my old service revolver [5" barreled M15] with .358 throats (pin gauged) demonstrated with the old Remington Target master 38 SPL WCs a 2" 12 shot groups at 50 yards with that ammo have .356 bullets. Those gave half the groups isze as my "standard" load using a 158 cast sized at .358 loaded over 3.5 gr Bullseye.

Speer did a test on a Colt Single Action .357 Magnum that had if memory serves something like .360 cylinder throats and a .355 grooves in the barrel. The big throats and tight barrel had negligable effect on chamber pressure.

Quote:

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Originally Posted by Don Purcell

Speer did a test on a Colt Single Action .357 Magnum that had if memory serves something like .360 cylinder throats and a .355 grooves in the barrel. The big throats and tight barrel had negligable effect on chamber pressure.

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It has me wondering if these larger throats, plus the cylinder gap, can have a positive regulatory effect on muzzle velocity:

Given that the bullets are a consistent alloy, they're going to take the same amount of effort to shove down the bore.

The powder charges and internal volume of each piece of brass will be close, but not 100% identical.

The Bullseye game is a comparatively low-pressure system where there's enough gas to safely poot a bullet out the barrel, but not a great deal more.

Under those conditions, would not the bore resistance on the bullet and the gas bleeding out the cylinder gap tend to reach some natural equilibrium creating a VERY consistent exit speed at the muzzle?