What does the number of rifling grooves change?

[boolia]

G'day,

Why do different rifles have a different number of rifling groves?

One has 4, another brand has 5?

Does it matter when choosing a rifle?

[Apollo]

I have a 3 Groove Pac-Nor .22BR.

Not much difference, easier to clean but has the same groove contact area as a 5 groove just less grooves for crap to accumulate.

Some say less grooves gives a little improvement in velocity, some also say they are more accurate. Six of one, half dozen of the other as the main influence is the nut behind the butt.

There are some barrels around, like the .22LR Brno with 12 grooves.

[jackles]

There are some barrels around, like the .22LR Brno with 12 grooves.

Sounds like fun to clean.

[Korkt]

Some say less grooves gives a little improvement in velocity, some also say they are more accurate. Six of one, half dozen of the other

I hear you about the 6 one, half dozen but on that note...

I can see (for arguments sake anyway, not saying it's a fact) that the increased bearing surface with less rifling could help accuracy.

What's the argument for less grooves increasing accuracy though? Increased velocity from less powder escaping through the rifling could be one thing, but that aint accuracy.

Are you able to expand on that at all?

[Apollo]

Sounds like fun to clean.

I have never had a "Micro Groove" barreled .22LR Brno but then again I don't clean Rimfire .22LR unless I am experimenting with ammunition from a different manufacturer which has a different wax coating, for some reason I suspect moisture in the barrel or it is going to be stored for a long period of time especially in a moist environment where I want to leave the bore with a coating of protective oil.

At best I might run a lightly oiled patch down the bore to knock out any loose powder then a dry patch or three before firing again.

I have a mate with a "Micro Groove" Marlin 30-30 and it is a pain to clean as it keeps copper fouling badly. What the reason is I don't know but suspect it might just be a rough bore and over time it will come good.

[Apollo]

I hear you about the 6 one, half dozen but on that note...

I can see (for arguments sake anyway, not saying it's a fact) that the increased bearing surface with less rifling could help accuracy.

What's the argument for less grooves increasing accuracy though? Increased velocity from less powder escaping through the rifling could be one thing, but that aint accuracy.

Are you able to expand on that at all?

I haven't even tried to compare or test any of the theories even with barrels from the same manufacturer with different numbers of grooves but you can have identical barrels that will shoot differently. Too many variables involved from manufacture to chambering and then even fitment into a stock plus any slight difference in ammunition used.

My 3 Groove Barrel is very easy to clean and doesn't seem to foul as easy as others but again it's a high grade select match barrel and any custom barrel I have used is far easier to clean than a run of the mill mass produced factory barrel plus they are way more accurate and should be due to the high cost and standards involved.

Some of the custom barrel manufacturers have a fair amount of information on the reasons they produce out of the ordinary designed grooved barrels if you can believe their screed.

[DaleH]

Just a historical take on the subject. the information taken from a post on another site but originating from an ENFIELD Book on the SMLE - At the end of the day, they couldn't see an accuracy difference between 5 and 2 groove rifling.


13 Barrel variations used in the Enfields (No. 4 and No.5) but the first 8 seem most applicable..

First Variation: 5 Groove Rifling Designated the "MK1"

Second Variation: 6 Groove Rifling (LEFT hand twist) Limited Use in mostly 1941 Dated SAVAGE Rifles and soon replaced by the Fourth Variation barrel
(NO mark #)

Third Variation: 4 Groove Rifling This barrel saw limited use on some No. 4 MKI rifles as well as some SAVAGE rifles. Also soon replaced by the Fourth Variation barrel.. (NO mark #)

Fourth Variation: 2 Groove Rifling Accuracy tests conducted in 1941 showed similar results to the 5 Groove barrels.. This barrel was designated the "MKII"
Uses chiefly on No 4 MKI* rifles (Savage & Long Branch) but also some later No 4 MKI rifles also Savage, Long Branch, & some BRIT rifles, including some MK 1/2, & MK 1/3 conversions..

Fifth Variation: 3 Groove Barrels tested in 1942.. Found acceptable and approved but not used for very long.. 1942 & 1943 Brit made No 4 MKI rifles..


Sixth Variation: 5 Groove Barrel designated "MKIII" Used in Brit rifles from 1943 & 1944.. These barrels were "DOLLIED", and NOT Broach Cut making for a Duller bore...

Seventh Variation: This is the #5 Barrel using a 5 Groove 1:10 Left hand twist.

Eighth Variation: 6 Groove Right hand twist found on No 4 MKI* Canadian Rifles (1950's Long Branch) Designated the "C MK 4"

[agentzero]

Some say less grooves gives a little improvement in velocity

Hmm, I'd have though move grooves would make less resistance and more velocity.

Not less grooves...

[boolia]

Just a historical take on the subject.

Good reading, Dale. Thanks.

[Grrzrr]

At the end of the day, they couldn't see an accuracy difference between 5 and 2 groove rifling.

Shouldn't come as a surprised really.

It would be very easy for any rifle maker to make a set of 3, 4, 5, 6 etc. groove barrels and see the results.

If one was a clear winner they'd be making all the rifles in that arrangement.

Thanks for the read on the Enfield stuff though