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Understanding reason for flat vs round rifiling

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Kilted Cowboy

Pilgrim
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Not understanding why flat rifling. I know the physical differences, but why 2 types of rifling?
Was one easier to do back in the day and has become tradition?
 
Not understanding why flat rifling. I know the physical differences, but why 2 types of rifling?
Was one easier to do back in the day and has become tradition?
Think about how barrels were rifled in the period - forge a tube, ream a round bore then use flat-bottomed cutters to make rifling. This would yield flat-bottom rifling.
 
No mystery. Over the history of firearm development there have been countless trials and experiments with different bores, riflings, etc. It seems the flat lands/grooves are more dominant simply because they may be easier to cut. There are round proponents who believe there are advantages. I have a rifle coming that will have round cut and am curious to see how it performs.
 
No mystery. Over the history of firearm development there have been countless trials and experiments with different bores, riflings, etc. It seems the flat lands/grooves are more dominant simply because they may be easier to cut. There are round proponents who believe there are advantages. I have a rifle coming that will have round cut and am curious to see how it performs.
Thanks for the info. I always try to understand why something was done a certain way, not just how it was done.
 
I always thought round bottom would be much easier to clean and to swab between shots. Don't recall the member but someone stated they actually foul worse per the straight cut having more room to disperse the fouling(?). Black hand probably correct on why. Easiest way to do it in the day with the tool available?
 
I always thought round bottom would be much easier to clean and to swab between shots. Don't recall the member but someone stated they actually foul worse per the straight cut having more room to disperse the fouling(?). Black hand probably correct on why. Easiest way to do it in the day with the tool available?
Look up the Colonial Williamsburg rifle-making video on YouTube. It shows the rifling process and the tools used.
 
I've Always been under the impression that round bottom was more common at least up to the latter part of the first half of the 19th century.

As to why I was done either way, wonder about that too.
 
I have both round bottom and 'traditional' square bottom rifled barrels. I think that it's a little bit easier to keep after the fouling in a round bottom rifled barrel, but I have no scientific proof of this … to do a study that would withstand the rigors of a peer review, you would need to some very extensive and very expensive testing.

My eldest daughter (who is now the chief public health officer for the city of Concord NH) and who's on the peer review committee for the American Public Health Assn, recommends the following:

you will need several sets of barrels, three to five at least, of the same caliber and length, half of the set will have radius groove rifling and half will have flat bottomed rifling.

you will need to use the same ball and patch combination, as well as the same load weight and the same powder (i.e FFFg or FFg).

you will need a very precise scale (duh)

shoot at least thirty five shots through each barrel, cleaning between each shot. since you have a very precise scale, you weigh the patch and the cleaning solution before you swab, and then after, and you know the weight of the crud removed from the bore. Keep track of each cleaning patch. Keep track of how many strokes you run the patch down and back up the bore, and keep track of how many patches you use to achieve "clean bore" status. (this is where the study gets a little subjective).

do this through all of your barrels... now you have a huge mound of funky cleaning patches, and you've burned a boatload of powder, and you've deafened the surrounding wildlife, and the rangemaster is rather tired of your incessant note- taking and you have what all researchers desire: a huge wad of data.

You know how much crud each rifling type required, and how many patches. you can do graphs and charts (in the manner of Alice's Restaurant - eight by ten color glossies)

You can publish your study in any one of a number of magazines, and on this site as well. People will be impressed.

You will have to explain to your wife, girlfriend or 'significant other' why it is that you have burdened the family budget with ten rifles, all of the same caliber, barrel length and rate of twist. You're on your own with this one.
 
"Not understanding why flat rifling. I know the physical differences, but why 2 types of rifling?
Was one easier to do back in the day and has become tradition?"

Why? People want them, marketing.

Lots of different type of rifling were tried in the past. Today you can get round bottomed rifling or regular. I bought one round bottom barrel. The width of the grooves appeared that the same width cutter was used as regular flat bottom rifling. The lands were too narrow IMO. They were also too deep, IMO. That made it impossible to get a patch an ball combo that sealed the bottom of the grooves. It never shot well. After a couple hundred shot fired, I removed it and replaced it with a conventional barrel. It is now in the junk steel pile. The new barrel was no perfect but with some work it is now capable of shooting well enough to make perfect scores at 50 yards.

The flaws I objected to were not round vs square grooves. IT had to do with excessive depth, lands too wide, and poor finish. I have no doubt a RB barrel can shoot very well if made properly.

Fouling qualities are definitely influenced by the finish inside the barrel. A very smooth finish definitely fouls less and loads easier. I think this factor is much more important than the shape of the grooves.

Accuracy is relative. A person who has low expectations maybe fine with a RB barrel and a loose patch ball combo. A person who demands 1" @ 50 yards would be dissatisfied with the RB barrel I bought.
 
It is not too difficult to find pictures of rifles with rounded grooves, at least in the muzzle. A quick thumb through the standard reference books should turn up a few. I'm having a hard time telling if this is round groove or square with the muzzle relieved with a round file...

Oerter-muzzle-email.jpg
 
It was/is thought by many that flat bottom rifling were harder to clean because the fouling would collect in the sharp corners and be harder to clean out. I've had several round bottom barrels and can tell you I can't tell a difference.
As for accuracy? I ordered a barrel from one of my mentors Mr. L.C. Rice many years ago and I asked him about the accuracy question. He said they sold more flat bottom rifled barrels to the target shooters but that was because flat bottom barrels were what they always bought. He didn't know how the accuracy actually compared.
So after many years shooting round bottom barrels I have my own opinions. If you can't shoot tight groups with a round bottom barrel then don't blame the barrel, your problem lies elsewhere. Do more testing of your lube and patches, just because you are determined to use "Grandpa's Original Joy Juice" as your lube doesn't mean your rifle wants to use it. The rifle always tells you what it wants, learn to listen to it.
If a shooter just can't shoot a RB barrel then send it to me. I'll pay shipping. And send you a free document on how to cure the flintlock flinch.
Currently I have a 20 year old Colerain .54 barrel and a 17 year old Rice .40 barrel. Both will shoot one hole groups, the .40 will place a round ball in a turkeys head at 50 yards.
I'm very satisfied with any of the profiled round bottom barrels I've used over the years.

Elnathan, that certainly looks like round bottom rifling to me. In fact it looks like it was cut with a fully radiused cutter. Most RB barrels are cut with a cutter that leaves a flat on the bottom with the corners radiused. A flat bottom has the corners sharp.
 
I prefer rifling that is radius bottomed in the grooves subscribing the same arc of it's circumference depth or nearly so just as the land tops do. True flat bottom groove rifling are often cut wide enough so that the mid point of the groove is nearly a high as the lands or bore diameter.
Round grooved rifling seems like a good idea but usually has to be cut deeper than square or radius grooves to get them wide enough to effectively grip the patch material.
I have an idea that both square and radius grooved rifling could be made better if the groove corners were rounded a bit rather than being cut sharp.
 
I've had both, Either are excellent shooters. ….But.... theirs always a But.....The most accurate rifle I have is a Colerain radius groove.

HH
 
After thinking about my response I checked my rifles with better light this morning. Both the Rice and Colerain have a groove with a full radius. I was speaking from the assumption that what I'd heard many years ago was fact. It wasn't in this case.
 
I've had both, Either are excellent shooters. ….But.... theirs always a But.....The most accurate rifle I have is a Colerain radius groove.

HH

I'll be receiving my new rifle soon and it will have a Rice roundy. I'll see then any difference. Actually, I do not expect it to perform better/worse than the flat/square cut barrels I use and have used. The only rifle I have ever had with round lands and grooves was an original CW experimental rifled musket in .72 cal. Even though there were pits in the bore it was very accurate. Not a heavy rifle, I didn't enjoy the recoil from the 120 gr. bp charges it required.
 
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