4R rifling?

[FrankG]

Or any worse hopefully!

Nope no worse.

 

[FrankG]

I don't believe the top of the land is rounded. More so the edges with it being sloped towards the base. The slope on the Mueller is less gradual than the bartlein shown. Almost like a blend between conventional and R.
View attachment 1173884

The “R” stands for Russian. Not radius!

It was a Russian design originally and Boots modified it.

 

[Drop Port]

It's a mullerworks cut rifle barrel. It wasn't a special order or anything that's why I was surprised to see the 4R. Didn't think that would be their go to land/groove choice.

Why not? 4 and 6 are pretty standard.

 

[InkedIan]

Why not? 4 and 6 are pretty standard.

Not the number but the style. Other than 5R I hadn't seen a R land as standard production. I'm aware 4 and 6 are common.

 

[Alex Wheeler]

I prefer a 4 over a 5 for the reason the reamer has opposing cuts with a 4. I do not like using a pilot on my reamers and I have to use one on a 5 groove to prevent the chatter that happens from tool push off. Do not take this as me saying a 5 wont shoot, they do and I personally have had some great ones.

 

[FrankG]

We've chambered 2 groove, 3 groove, 4 groove, 4R, 5 groove, 5R, 6 groove, 7 groove, 8 groove, 10 groove and 12 groove barrels in calibers ranging from .20cal to 20mm and we don't see a difference.

The only times we have problems with chatter is when the reamer wasn't made/ground properly more often than not.

Also in larger calibers say starting around 338 and bigger....I feel there is more flex in the body of the reamers and chatter can show up more/be more of an issue. Just nature of the beast. Is it a big problem? No but I'll say you will see it at times. Seen it in 4 groove, 6 groove and 8 groove barrels plenty of times.

Also when this happens it usually will happen with a new reamer in conjunction with the bigger caliber. I showed Scotty out in the shop how to wrap wax paper around the reamer when cutting a chamber and chatter/vibration issues went away. I told him after about 5 barrels the reamer usually will settle down and you won't need the wax paper anymore.

 

[Alex Wheeler]

Frank, what Im talking about is not actual chatter. Its tool push off. In a 4 groove your cutting opposing lands at the same time. In a 5 theres no opposing force when cutting the land. So you need to support the reamer with a snug pilot. Even still, if you put a .0001" indicator on the freebore, Id bet you see the needle bounce 5 times in a rev, may only be .0001 but its there. I would say most guys dont even notice it, and if your not holding the reamer in your hand you would never feel it.

 

[Drop Port]

Frank, what Im talking about is not actual chatter. Its tool push off. In a 4 groove your cutting opposing lands at the same time. In a 5 theres no opposing force when cutting the land. So you need to support the reamer with a snug pilot. Even still, if you put a .0001" indicator on the freebore, Id bet you see the needle bounce 5 times in a rev, may only be .0001 but its there. I would say most guys dont even notice it, and if your not holding the reamer in your hand you would never feel it.

I delete my post explaining this for fear of being flamed. With that being said one of the best barrels I've had was a 5R Bart. Given (10) 4-groove, (10) 6-groove and (10) 5 groove to chamber all else being equal I would bet on the 4 and 6 groove having a higher percentage of better chambers. Just my.02

 

[Alex Wheeler]

I dont want people taking it out of context, thats hard to do online. I chamber a lot of 5r barrels and get good results and guys shoot them very well. One of my best was a 5c, I am currently shooting a 4 groove Bartlien that Im very happy with. I like to try different things. We have 3,4,and 5 groove barrels from Krieger, Bartlien, Lilja, Broughton, Rock creek, and Brux all shooting at the top level here. What Im talking about is something I see in the shop, not necessarily on the target.

 

[Concha]

Thanks guys. Great post!