Different types of rifling grooves

S

simonrichter

New member
Does the form of the rifling grooves have any impact on the performance of a gun? I'm NOT reffering to classic rifling vs. polygonal, I'm talking sbout the intersection of the grooves which is commonly rectangular but could e.g. also be V- or U-shaped.
And btw, are there any contemporary handguns that feature other than "square" rifling grooves? (Again, apart from polygonal rifling)
 
A quality barrel done with any of the popular rifling methods will be a good shooting barrel, while a barrel with any of those same techniques done poorly will be inaccurate. Modern reputable handgun manufacturers have found tried and proven methods that produce affordable barrels that are also quite accurate. Most handguns are more accurate than the shooter that owns them. Most folks believe that the rifling with the sharpest cut edges produce the best accuracy....thus the square rifling. Those same barrels tends to shoot out the fastest because of those same sharp cut edges. Proponents of polygonal rifling claim it is most resistant to being shot out. S&W uses gain twist rifling in some of it's .460 handguns to help the rifling from getting shot out close to the forcing cone.
 
Nope. It's strictly a manufacturing thing. You can start an enormous argument if you say a Lee-Enfield's barrel is worn out because of the shallow rifling. Worse if you say 2 grooves isn't as accurate as 5 or 6.
 
I don't know of a pistol barrel other than "land and groove" or the melted looking "polygonal."

You can get rifle barrels with 5R - 5 groove Russian profile - rifling, which looks a lot like the old "trough shaped" rifling, with the grooves tapering from top to bottom. There were and may still be muzzleloaders with round bottomed grooves for easy cleaning. Krieger makes Alex Henry barrels and Shilen has ratchet rifling with only the leading edge square, the trailing edge of the land tapering off to reduce friction.
 
In some calibers-9MMP, e.g. rifling and rate of twist is important in getting god accuracy with lead bullets. Marlin switched from Micro-Groove to Ballard rifling at the request of CAS/SASS shooters.
Sounds like an interesting testing/experimentation session subject.
 
9mm P twist is nearly as bad as .223. It is generally overstudied and overemphasized except at the extremes.

Anecdote Alert:
Although at one time, if you wanted to shoot lead bullets - probably swaged in Euro factory target ammo - SIG would sell you a 20 twist P210 barrel for the purpose. Their regular barrel is the Euro standard 10 twist, going back to Ol' George and DWM. Or is it really 9.84", four turns to the metre?

Randy Lee is getting Barsto to make barrels for Apex with a 10 twist and tighter fit than stock in the S&W Plastic M&P. Interestingly enough, the choice of twist has little to do with the bullet. He says the torque reaction to the fast twist improves the lockup. So did Elbert Searle at Savage 110 years ago.

Ed Harris once had Barsto make him four BHP barrels, all their standard diameter and 16 twist, but with different chamber throats. All were more accurate than the FN 10 twist, hardly a surprise. But then he got one made out of a .38 Special blank, .357" 18.75 twist. It was more accurate than the .355" 16s.

Marlin's return to 6 groove rifling in revolver calibers was a boon to lead bullet shooters, as in CAS. I have not seen a real Ballard barrel or a close description of what its rifling plan was. But Marlin once owned Ballard and it is such a fine old name. I recall when the 1895 reissue came out in the 1970s and brought back the .45-70 repeater. Catalog said "Conventional rifling for lead and jacketed bullets."
 
Last edited:
Those same barrels tends to shoot out the fastest because of those same sharp cut edges. Proponents of polygonal rifling claim it is most resistant to being shot out.
Click to expand...
It is my understanding the barrels do not get shot out from the friction of a bullet passing down them but from the throats (rifle), and the forcing cones (revolvers), becoming eroded by the superheated gases. Therefore, the type of rifling, cut, button, or polygon should not make any difference. Is that not correct?
 
Shilen has ratchet rifling with only the leading edge square, the trailing edge of the land tapering off to reduce friction.
Click to expand...

Shilen always experimented. Back in the mid 70's I had one of his first bench rest "funny Barrels" which was octagon. It shot fine but not any better than anything else. I never shot it long enough to see how long it lasted.
 
Simon, I don't know of any pistols that don't have one of the two types you mentioned. Of those two, I haven't been able to detect any difference in accuracy, but the polygonal type does seem to have a slight velocity advantage over similar length barrels with conventional rifling. The Schuemann Barrels website has good information on this subject.

BTW Mr. Watson, I kept a copy of that C.E. Harris article, "The 9mm can be accurate", Rifle Magazine July-August 1986. It was the most detailed discussion of handgun chamber types, rifling leades, twist rates, etc. effects on accuracy that I can recall having seen at that time. Back in the day, I tried all manner of lead bullets in standard Hi Powers with the 1 in 10 twist and NATO chambers. Results were unspectacular to say the least. I had Bar-Sto barrels installed in 2 or 3 Hi Powers. Problem solved. The Bar-Stos did produce very good accuracy with lead bullets, but never as good as JHP bullets.
 
Some have claimed that Micro-Groove rifling was not accurate .NOT true. However Micro-Groove rifling is more sensitive to bullet hardness and diameter !!! When you make the bullets of the proper hardness and diameter they are very accurate.
Bought bullets usually don't have much accuracy !
In the old black powder days they found that sharp cornered grooves held burned powder that was hard to remove and rusted .
 
You must log in or register to reply here.
Back
Top