Shallow or deep rifling

[tom in nc]

After reading that some production guns, (T/Cs according to one person), do not have rifling cut deep enough, I wonder. How deep does rifling need to be? Would it differ with the caliber of the barrel? Or with the number of grooves? The purpose of rifling is to impart a spin on the projectile, right?
I just need to know how someone can look in the muzzle and say the grooves are not deep enough.

 

[diyj98]

I just need to know how someone can look in the muzzle and say the grooves are not deep enough.

I'd say they can't. I've heard various theories on rifling depth, but don't know if any of them are 100% correct. I've always figured deeper rifling made it hard to get a good seal. I always thought TC barrels were fairly well thought of.

 

[wiscoaster]

IMO if one uses a "PC" projectile the firearm that shoots it should also have "PC" rifling. This is one disadvantage of my repro 1861 Springfield that doesn't have PC rifling and therefore is not terribly accurate at shooting PC repro Minie balls.

 

[Cabincritter]

Rifling depth depends on what type of projectile the rifle is made to shoot. A general rule of thumb is that for a patched round ball, one wants deep grooves to catch and hold the patch. Rifles shooting an elongated bullet, as opposed to a ball, do best with shallower grooves. Deeper rifling will also hold more fowling, and allow one to shoot longer with out cleaning.TC used a comprise type of rifling in both twist and depth. They shoot reasonably well with either a ball or a bullet, but not particularly good with either. It is a compromise.

 

[nchawkeye]

Barrels made by Rayle, Rice, Green Mountain and others, for round ball shooting typically have cut rifling .012-015 deep.

Production guns typically are button rifled, .006-008 deep.

 

[Rock Home Isle]

After reading that some production guns, (T/Cs according to one person), do not have rifling cut deep enough, I wonder. How deep does rifling need to be? Would it differ with the caliber of the barrel? Or with the number of grooves? The purpose of rifling is to impart a spin on the projectile, right?
I just need to know how someone can look in the muzzle and say the grooves are not deep enough.

I stick my pinky into the muzzle and turn my wrist as my fingernail glides over the rifling. If my fingernail catches on the ridges of the rifling…I’m happy and it’s deep enough.

 

[Kansas Jake]

There are many criticisms of TC shallow rifling and for someone who is in the top 5-10% of shooters it may make a difference. Most of us like to think we are one of them but the reality is we are more average. My old TC has been much more accurate than for me for the 50 years I’ve had it.

 

[EC121]

IMO. Any rifling deeper than about .008” is marketing. It just takes enough to spin the ball. Fouling storage is not needed because I wipe about every three shots no matter the depth. A good wet ball patch does more than storing the fouling in deep rifling. Over the years I have had all the brands: Douglas, Montana, Orion, Rayle, Rice, Colerain, H&H, Hoyt, Getz, Paris, etc. They were all accurate even with their various rifling depths and twists. A ball and patch sized to properly fit the barrel are more important than rifling depth.

 

[nhmoose]

I'd say they can't. I've heard various theories on rifling depth, but don't know if any of them are 100% correct. I've always figured deeper rifling made it hard to get a good seal. I always thought TC barrels were fairly well thought of.

Sure that's why Green Mountain grew so fast and good.

 

[diyj98]

Sure that's why Green Mountain grew so fast and good.

I guess all those other barrels they make didn't have anything to do with it.

 

[EC121]

The rifling on GM barrels wasn’t any deeper, but the grooves were wider allowing slightly larger balls to be used. The wider grooves also allowed a better seal. That and the slower twist made them better than the T/C factory barrels which were intended primarily for their Maxi-balls.

 

[nhmoose]

They came after ML barrels, on the third or 4th owner now.

 

[nhmoose]

The rifling on GM barrels wasn’t any deeper, but the grooves were wider allowing slightly larger balls to be used. The wider grooves also allowed a better seal. That and the slower twist made them better than the T/C factory barrels which were intended primarily for their Maxi-balls.

They GM, had deeper rifling. Fact.

 

[EC121]

Let me correct myself. I meant they weren’t any deeper than the other barrels on the replacement/ custom barrel market, and they were much deeper than the T/C barrels.

 

[maillemaker]

IMO if one uses a "PC" projectile the firearm that shoots it should also have "PC" rifling. This is one disadvantage of my repro 1861 Springfield that doesn't have PC rifling and therefore is not terribly accurate at shooting PC repro Minie balls.

What does "PC" stand for?

 

[Grenadier1758]

@maillemaker, PC stands for Period Correct. It can be used as a pejoratives term when describing a T/C "Hawken" or an Investarms rifle with coiled springs in the lock as these were not features of rifles produced before 1850. It can be used when describing a Ruger Old Army or an 1858 Remington replica revolver with target sights or a Tingle pistol. The modern target Minie' balls or Maxi-Balls are not PC.

Percussion lock firearms are not PC in the period prior to 1832.

My 1809 Derringer Rifle is not PC in the context of the April Trade Faire at Fort de Chartres which is striving to loosely represent the period in the Illinois Country from 1765 to 1780.

Now a lot of the PC/not PC debate can be overlooked because the item is in the tradition related to the period. After all, none of the rifles I am aware of use skelp forged barrels and most of lock components are cast, not forged. PC or not PC are terms we should be aware of but not used as a means of exclusivity. We should be accepting of items that are used in the tradition intent. Juried events are an exception

 

[wiscoaster]

..... PC stands for Period Correct. It can be used as a pejoratives term ......

Now a lot of the PC/not PC debate can be overlooked because the item is in the tradition related to the period. .....

In my case, I was using it in the context of "as it was done back in the day".

 

[N5JIF]

My experience with both a TC and another rifle is shallow groves work better with something other than round ball. A Rebore with deeper groves made a big difference

 

[Mike in FL]

I had a 50 Chambers rifle with deep cut but round bottom rifling. Never have I had a black powder gun so difficult to clean. Over an hour each time I cleaned it; even then the last patch patch did not come out perfectly clean. I even bought one of those flushing thingies to try and make it clean. That didn't work. I hated to put it away with what I considered a less than clean barrel. Finally sold it

 

[Rifleman1776]

TC barrels shoot fine. Nevertheless my preference is deeper rifling with prb.