Pietta Rifling

[nkbj]

When did Pietta change to narrow land rifling?

I was checking out a Pietta 1858 this morning, mainly looking to see what the dimensions were for fitting it with 230 or so grain bullets. The date code shows 2019 manufacture.

Setting the ID mic's side of the calipers to 0.446", the chambers will not admit it in the axial direction (from cylinder center towards the OD) but will let it in when the orientation is rotated 90 degrees. So the chambers are consistently slightly egged in the same orientation with the minor diameter being 0.445"-0.446" and the major diameter is about 0.446"-0.447".

The barrel is 5 1/2" long. The groove diameter is right at 0.450". The twist is much quicker than the earlier Pietta revolvers. The lands are much more narrow than the grooves and the rifling is shallow, more like a .45ACP pistol than a percussion revolver. I'm wondering how it is going to group with shallow skinny lands and substantially undersized bullets.

So this got me to wondering, when did they change the design of their rifling? Only on the 1858's with screw-in barrels or on the open top designs as well? Anybody got a handle on this?

 

[Smokey Plainsman]

Get a set of pins gauges for more accurate measurements.

 

[45D]

They do great with 45C conversion cyls. I believe their open tops have fast twists as well. Uberti's have been fast for a long time ( at least 2010). I just finished installing a new Kirst gated equalizer in my 2019 5 1/2" Pietta. Looking forward to shooting it soon!!

Mike

 

[nkbj]

Anybody know when Pietta changed the geometry of their rifling to narrow lands?

 

[M. De Land]

When did Pietta change to narrow land rifling?

I was checking out a Pietta 1858 this morning, mainly looking to see what the dimensions were for fitting it with 230 or so grain bullets. The date code shows 2019 manufacture.

Setting the ID mic's side of the calipers to 0.446", the chambers will not admit it in the axial direction (from cylinder center towards the OD) but will let it in when the orientation is rotated 90 degrees. So the chambers are consistently slightly egged in the same orientation with the minor diameter being 0.445"-0.446" and the major diameter is about 0.446"-0.447".

The barrel is 5 1/2" long. The groove diameter is right at 0.450". The twist is much quicker than the earlier Pietta revolvers. The lands are much more narrow than the grooves and the rifling is shallow, more like a .45ACP pistol than a percussion revolver. I'm wondering how it is going to group with shallow skinny lands and substantially undersized bullets.

So this got me to wondering, when did they change the design of their rifling? Only on the 1858's with screw-in barrels or on the open top designs as well? Anybody got a handle on this?

My pin gauges usually show bore tightness under the threads and looseness in the muzzle. The chambers are usually tighter than the barrel grooves and as you noted oblong. I have reamed most of my revolver chambers round and to groove diameter. I don't think either Pietta or Uberti use gain twist any more as I believe some original Colts were.

 

[45D]

I don't think Uberti or Pietta (or ASM or ASP et.al.) have ever had gain twist. Even Colt 2nd gens, 3rds, Sigs didn't have gain twist. Maybe some Pedersoli offerings have it or had it but gain twist is pretty rare.
If it made that big of a deal, I'd think FA or BFRs or even Ruger wold have models with that type rifling. How bout Korth? Do they use gain twist?

Mike

 

[M. De Land]

Yeah gain twist is single point cut not broach cut , buttoned or hammer forged so it wouldn't make sense for low cost modern mass production.
It makes sense for paper patched bullets as it will unfailingly cause uniform patch expulsion but I could never quite figure the reason Colt used it for revolvers and round balls. They must have though their was some advantage but I sure don't know what it would be.

 

[nkbj]

Pietta rifling; old style versus new style.

 

[nkbj]

Going to try various bullets before modifying those undersized chambers on the new style revolver.
Here's a 250 grain thin skirted hollow base wadcutter to try out for plinking.
It's a close fit to the undersized chambers but slips in this far. The out of round misalignment on the mold blocks for the front of the bullets may be "just right". For certain the lube grooves will help keep fouling soft and inhibit flash overs.
The reduced powder charges may work out really well for accuracy. We'll see.

 

[nkbj]

Here's another to try out, RCBS #45-220-CAV with the rear ends of the bullets sized down in diameter to slip into the chambers.

Kinda pessimistic about shooting that bullet undersized in any pistol or revolver with narrow lands.

 

[SDSmlf]

I don't think Uberti or Pietta (or ASM or ASP et.al.) have ever had gain twist.

Look up the specs for the Pietta 1858 Shooters model.

 

[45D]

Look up the specs for the Pietta 1858 Shooters model.

The Pedersoli examples have "aftermarket" barrels as probably the"Shooters " model from Pietta. The "run of the mill" examples don't and never had gain twist rifling that I know of. I'm not really sure it makes any difference other than being "historically" correct. Does Ruger, Freedom Arms or Magnum Research offer gain twist rifling?

Mike

 

[Bad Karma]

Look up the specs for the Pietta 1858 Shooters model.

The Pedersoli examples have "aftermarket" barrels as probably the"Shooters " model from Pietta. The "run of the mill" examples don't and never had gain twist rifling that I know of. I'm not really sure it makes any difference other than being "historically" correct. Does Ruger, Freedom Arms or Magnum Research offer gain twist rifling?

Mike

I’ve owned 3 of the Shooters. One had gain twist rifling, (the purty one) it wasn’t notably more accurate than the other Shooters or any of the Rugers. Fine accuracy but not worth any extra expense.

 

[Bad Karma]

Here's another to try out, RCBS #45-220-CAV with the rear ends of the bullets sized down in diameter to slip into the chambers.
View attachment 129800
Kinda pessimistic about shooting that bullet undersized in any pistol or revolver with narrow lands.

And yes, that style of rifling would most likely require better chamber/bore fitting with any bullet. But who knows, could be amazing right out of the gate.

 

[Relic shooter]

I’ve owned 3 of the Shooters. One had gain twist rifling, (the purty one) it wasn’t notably more accurate than the other Shooters or any of the Rugers. Fine accuracy but not worth any extra expense.

The gain-twist rifling used on original Colts & Remington C & B revolvers were more accurate because they had much deeper rifling that better engaged a ball or bullet.
The 'shooter grade' modern repro 58 Remingtons I've seen have had much shallower rifling, I found they performed well with lighter loads but projectiles tend to skid with heavy loads.
If not concerned with looking original & want top notch accuracy I think most will agree that the ROA remains the best modern repro performer.
relic shooter

 

[Stantheman86]

Colt 2nd Gens have the deeper "period style" rifling that other Ubertis don't , I don't know the exact name for it

 

[bang]

A minute mount of oblong in chambers should be corrected at the forcing cone.
For sure shoot it before any adjusting.

 

[Johnny Tremain]

When I measured the cylinder, I was sad to see .003 deviation between holes.
Then I did the barrel. .440-.443.

 

[Relic shooter]

Yeah gain twist is single point cut not broach cut , buttoned or hammer forged so it wouldn't make sense for low cost modern mass production.
It makes sense for paper patched bullets as it will unfailingly cause uniform patch expulsion but I could never quite figure the reason Colt used it for revolvers and round balls. They must have though their was some advantage but I sure don't know what it would be.

Gain or progressive twist rifling was very popular in early days in many upper quality rifles because it produced superior accuracy in both rifles & pistols because it allowed a patched round ball or slug to fully seated before engaging the faster twist area in the bore.
With original Remington & Colt revolvers the almost non-existent rifling twist at the breech of the barrel allowed the slightly oversized ball or bullet to jump the cylinder's gap & become fully engaged in the deeper rifling before reaching the faster twist rifled area in the forward 2/3rds end of the barrel.
** Of course there are always exceptions to the above or any type of rifling twist & depth, these circumstances largely depend on what type of firearm your shooting & if hard cast bullets are used that are better suited to shallower depth rifling.

 

[Bad Karma]

Gain or progressive twist rifling was very popular in early days in many upper quality rifles because it produced superior accuracy in both rifles & pistols because it allowed a patched round ball or slug to fully seated before engaging the faster twist area in the bore.
With original Remington & Colt revolvers the almost non-existent rifling twist at the breech of the barrel allowed the slightly oversized ball or bullet to jump the cylinder's gap & become fully engaged in the deeper rifling before reaching the faster twist rifled area in the forward 2/3rds end of the barrel.
** Of course there are always exceptions to the above or any type of rifling twist & depth, these circumstances largely depend on what type of firearm your shooting & if hard cast bullets are used that are better suited to shallower depth rifling.

Robert Hoyt still rifles barrels this way. He says they all realize gains in velocity as compared to standard constant rate rifling.