4 Groove Rifling

[arcticap]

I have an unfired Miroku .45 Kentucky rifle and I noticed that the rifled barrel has 4 lands which are just a little bit wider than the 4 grooves. The rate of twist is 1 in 66".
Would the number of grooves greatly affect the potential accuracy of the barrel or could it be just as accurate as one having more grooves?
Are there any known advantages or disadvantages to having rifling with only 4 grooves, such as being less prone to fouling or is it a more traditional style of rifling? Or could it have been rifled that way simply as a cost saving measure?

Also, I had a Miroku .45 Kentucky pistol that only had 3 groove rifling. Why would they use a whole different rifling process for the different models rather than to just build a Kentucky pistol using the same 4 groove rifling?

 

Hear is a thought, and frankly it has nothing to do with ML -but, it does with shooting in general. During WWII there was a manufacturing (production) change made to the rifle barrels for Garands. It resulted in the production of "Two grove" 30/06 rifle barels. All the tests I read said that they were just as accurate as the barels that were previously produces with a greater number of lands and groves. Perhaps they wore out faster? But when you are talking a life span of 250,000 ++ rounds -- who cares? If a rifle shoots accruately - I personally don't care it it has "micro grove" rifling; deep / shallow rifling; left / right hand twist rifling; or a ROT of 1x900.

 

[Blizzard of '93]

I saw one of those at the gun show while back and noticed that checking the bore. Looks like a question for Paul V. to me.

 

[bob308]

you are in the right barn but wrong stall. it was not the m1. it was the 03a3 that production was streamlined by going to 2 grove barrels.

i have one of both and they both shoot the same hold about the same groups. my 03a4 sniper has a 2 grove barrel.

 

[arquebus]

Alot of the US-made (Savage) No.4 Enfields in .303 British were also made with 2-groove rifling. They have a reputation for inferior accuracy though.

 

[paulvallandigham]

What is the Rate of Twist on that pistol? ROT is much more important that how many lands and grooves a barrel is given. That 1:66" ROT makes the .45 rifle a good Round Ball shooters, but not good for shooting conicals, unless, maybe you can get a ballette to stabilize in that slow twist.

Why did the gunmakers 200 years ago make ML rifles with 7 lands and grooves? Its certainly easier to divide a circle by 6 than by 7 ! If you look through Shumways books on Golden Age rifles an uncommon number of the guns have 7 lands and grooves. I have never found a good explanation for that fact. Anyone out there know?

 

[Hunter66]

Isn't 7 supposed to be a lucky number? Some of us need all the luck we can get! :rotf:

 

[bob308]

i was told it was because 7 days in the week. and there were some or the religous reasons. like putting a fish inlay in the stock was to keek the gun from being hexed.

another thory is it shoots better if there is a land oppisite a grove.

 

7 was considered the "perfect number". God completed the creation in seven days.

Most of the smiths were Reformed Lutheran and Morovian.

Everything they did was supposed to glorify God. That is why so few of the early guns were signed. Signature was a show of pride and unacceptable from a Christian.

Many of the subsects were also vegitarians!

Vegitarian gunbuilders. :hmm:

 

[kentucky bucky]

What is the Rate of Twist on that pistol? ROT is much more important that how many lands and grooves a barrel is given. That 1:66" ROT makes the .45 rifle a good Round Ball shooters, but not good for shooting conicals, unless, maybe you can get a ballette to stabilize in that slow twist.

Why did the gunmakers 200 years ago make ML rifles with 7 lands and grooves? Its certainly easier to divide a circle by 6 than by 7 ! If you look through Shumways books on Golden Age rifles an uncommon number of the guns have 7 lands and grooves. I have never found a good explanation for that fact. Anyone out there know?

Yes!
I believe it was easier to refresh a bore with an odd number of lands. That way a land was across from a groove instead of another groove. They knew that with any use that the rifle would need "freshing out" due to the softer metals in the barrels back then.

 

Right barn - wrong stall --- I lovde it!! :rotf: BTW - I sent an email off to Bruce Canfield to get some verification on the 2 grove application. I still think it was the Garand, but I have been wrong before. :winking:

 

[paulvallandigham]

Thanks for the information on the 7 groove rifling. I had been told there might be some religious basis for the odd number, but never learned the details. I do think, however, knowing the practical nature of early gun makers, that the second reason give, that of having a land opposite a groove to facilitate cutting or frewshening out a barrel makes the most sense. If you have ever rifled a barrel with a hand made cutter and rod, you understand the value of this arrangement.

If you have never seen an original rifling machine used, go to Dixon's Gunmaker's Fair, in Pennsylvania, in the summer, or get out to Toal's Hall in Iowa, where you can rifle your own barrel!
[url] http://www.midiowa.com/toadhallrifleshop/[/url]

I am sure there are other sites around the country where you can find or watch original rifling machines made and used. What is so special about the work done at Dixon's, is that the collected gun makers have made a new gun each year, splitting up the work, with a barrel rifled at the rifling machine as a demonstration, so that the gun is complete and is auctioned off the next year to defray the expenses of putting on the fair. You can be lucky enough to see your barrel rifled- even take a turn at the process yourself, and if you are the lucky bidder, or winner, you can own the gun you saw made! A blacksmith with a forging block demonstrates how barrels were made by welding flat steel stock around a mandrill, the old fashioned way. If you don't know how it used to be done, you can['t understand what most of this particular topic is talking about. Still, figuring out how to put a groove every 51.43 degrees is a lot of work! Only because I know how rifling machines are made does that cease to be much of a problem in actual practice.

 

[Zonie]

"...Why did the gunmakers 200 years ago make ML rifles with 7 lands and grooves? Its certainly easier to divide a circle by 6 than by 7 ! If you look through Shumways books on Golden Age rifles an uncommon number of the guns have 7 lands and grooves. I have never found a good explanation for that fact. Anyone out there know?..."
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The reason for 7 grooves may be, as suggested because of religious beliefs, but the reason for an odd numbers like 7, 5 and 3 being used was due to the way the rifleing was cut.

Rifleing was cut one groove at a time. The single cutter exerts tremendous pressure directly away from (or opposite from) the area being cut by the cutting blade or teeth.
By having an odd number of grooves, the area of the cutting tool directly opposite the cutter will be resting against and supported by the uncut bore of the gun even after all of the grooves have been formed.

If there were an even number of grooves like 8, 6, or 4 the area opposite the cutter will be unsupported after 4, 3 or 2 grooves have been formed. The area that needs to provide the support for the cutter blade will be one of the previously cut grooves thus no support will be available.

As for the 2 groove military rifles, by the time these guns were made, broaches which cut all of the rifleing grooves at one pass had become available.
Because these broaches cut in all of the grooves at the same time, in one pass of the broach, the need for support of the cutting areas common to the older method is not needed.

zonie

 

[bob308]

glad you liked it . i have rebuilt a lot of m1's and never have seen one with a 2 grove barrel. i have shot and own a lot of 03a3's and they are the only ones i have seen with the 2 grove barrel. and only on remington rifles. it was remingtons idea to use 2 grove so it would speed up production. there were alot of the 03 and 03a3 rifles used in ww2 not everyone got a m1.

as for the savage no.4's i have shot a few of them and never had any problems with them other then the one that the barrel looked like a washed out pice of pipe. in fact i have seen a few no4 savage made rifles with no. 32 scopes on them set up for sniping by h&h.