Different types of rifling and there uses.

[J E Custom]

I would like to discuss the many different types of rifling and there uses. (To learn something)

Like everyone, I have my favorite rifling designs for different uses but would like to hear other members view and use preferences.

This is not about twist rates,(Another discussion) It is just about the many different kinds and there advantages and disadvantages. We currently have everything from smoothbore (No rifling) to Micro
(10 or more groves) on hunting/target rifles, so I though it would be interesting and informative.

We also have non conventional rifling like Polygonal, Gain twist and ratchet designs, so feel free to discuss any of these that you have had personal experience with (No hear say please). The grove count of your favorite rifle is also Important. (2,3,4,5,6,8 and 10) and the pros and cons of them.

PS : Please keep it civil.

Thanks
J E CUSTOM

 

[adam32]

5c rifling is so far my favorite; extremely accurate, very easy to clean and seems to be a bit quicker then other barrels.

 

[Mikecr]

Apparently nobody has proved that any form is better than others.
So important to me, for hunting barrels, is just that it's cut rifled and lapped.

 

[HARPERC]

I couldn't tell you the type of rifling any of mine have. Half a dozen or so different brands used, and good ones from all of them. I know twist isn't the question you're asking, but the only issue I've had to date is when the twist isn't A) What I ordered, (most of us I think assume this too much), B) Too extreme one way or the other for the bullet chosen. I would also like to hear discussion from those that have studied it enough to have an opinion.

 

[shortgrass]

A good barrel is a good barrel. Stick the chamber concentric with the rifled bore and it's pretty hard to go wrong.

 

[Canhunter35]

I appreciate cleaning my 5r rifling and how it shoots. An odd number of grooves makes sense to me on less deformation of the bullet. I will most likely buy a 5r barrel for my next one.

Curious if anyone has experience/information on gain twists?

 

[tim_w]

I think as much as different rifling designs effects various aspects of ammo performance etc are the ratio and dimensions of groove to land themselves not just general number or design. Not only in width but depth/hieght. As an example you can get different effects from 4 grooves that uses 50/50 land to groove ratio versus say where the land are 1/2 width. The larger and taller lands the harder it can be on thin jackets when speed get up. Kirby Allen had to make adjustments from the standard 3 groove dimensions. The land had to be reduced and groove increased to keep bullets to hold together.

The other issue that is sort of at odds with lower friction from engraving is throat live. Obviously the more lands the smaller they are and the faster they will erode. The larger and taller they are the slower they will.

I like the R or canted lands on the side as you really do not lose surface area as much for ease of engraving force. I also like a slightly taller land and a bit narrower as opposed to the flip. I have found it seems to work better for throat life. I also like non-opposing land and grooves (odd number) as I feel its deformation force is less but I have only tested this with strain gauge. It minor either way but I figure why not try to get every bit you can as it adds up.

When you get up into the big long real ELR bullets etc I think things can change somewhat as other considerations come into play as even the smallest of things have a effect at 2 miles.

 

[HARPERC]

......Kirby Allen had to make adjustments from the standard 3 groove dimensions. The land had to be reduced and groove increased to keep bullets to hold together......The other issue that is sort of at odds with lower friction from engraving is throat live. Obviously the more lands the smaller they are and the faster they will erode. The larger and taller they are the slower they will.......

Interesting point, the extreme cartridges may have different needs than the more moderate cartridges.

 

[HARPERC]

.....Curious if anyone has experience/information on gain twists?.........

I can't link it to here, but Bartlein has a small discussion on their site. I just ordered a barrel from them, and chose not to go with a gain twist after reading.

 

[dok7mm]

I am not able to quantify why, but I am having very good luck with the 5R Bartlein configuration and they have all been very accurate and clean up very well. My absolute best rifle wears a 4 groove Kreiger. Like most, I sometimes wonder just what determines the ideal groove pattern for a given bullet and velocity. Til then, I just keep "dancing with who brung me"

 

[tim_w]

Are you speaking of the part on Bartliens site in the Faq section?

If so that is not against or negative to gain twist from what I read. As I read it the negative part was specific in the comparison to button rifling and that the buttoning if not done very carefully can speed up and slow down in one barrel blank. Obviously a decrease would be disastrous. A increase and then decrease even worse. We already know just from looking that most buttons are not accurate to 0.1 of twist rate and it seems there are some that are up to 0.5 off expected.

Here is the quote near the end of the topic

"I feel even a slight gain twist will help accuracy wise and not hurt a jacketed bullet shooter as well." He directly quotes Pope a few times who was a proponent of gain twist.

I think it depends on the extreme of the gain in the twist for increasing the angle of the rifling. By changing the angle you are changing the engraving position on the bullet. With small amounts this IMO has little to no real world effect ( i.e. bench rest comps have been won with gain twist so they produce very small groups) But I think when you get past 1-1.5 increase the the angle change might become an issue. I honestly have never tested it. I have only used .5 to 1 inch increase in twist rate. Where I think it comes in handy is when you have thin jackets and fast twists. We have had issues in the past keeping a number of caliber bullets like the Berger hunting or j4 jackets together when vel get up there with the faster twists for these longer bullets.

I think in general and not going to extreme starting bullet a bit slower spin and increasing it has some benefits.

Rock has had a slight twist increase in most all his barrels for how long now? I think its only .5 gain but still its there.

I can not speak to the bore rider setup that had bullets with the driving bands and extreme gain twist of increasing 5 to 6 inch or more thru the barrel. I have no experince what so ever with that but I do understand the theory and what they were after just no first hand knowledge so I can not speak on it.

I think over all small to moderate gain twist has benefit as we get into these faster and faster twist to stabilize these heavier higher bc bullets as they just keep getting longer and longer not to mention mono bullets. In the case of jackets I think even more so. As with jackets and high vel you get into the same situation why gain twist worked well in lead. Also the slightly slower start into the lands IMO s never a bad thing.

Its also why I like a radius on the rifling on the nondriving edge. IMO it allows for a easier start into the lands and thus less peak pressure from the sudden friction. I know the barrels I have setup this way always are very fast and can take hotter loads.

I think 3 groove for maximum life and over all I like 5 groove as my standard goto with a radius on the trailing side of the land bore intersect. I do not think this combo has any positive effect on accuracy but slight benefit in vel and pressure and I guess copper fouling and does not stress the jacket as much.

 

[HARPERC]

I mentioned the article as I thought it was balanced, and mentioned some variables, bullet construction being one.

Could have been clearer about why I didn't go that route.

I've got on order a 1-6" twist, to stabilize an all copper .264 bullet. In discussions with others here-the theory of reducing initial pressure was mentioned, from reading Bartlein's view I didn't see a clear advantage pressure, velocity wise, in that section "shooters report" and "my only guess" jumped out at me.

Also we were talking what I would guess as more "extreme twist" 10"-6". The comment was made "With a gain twist the bullet can not go to sleep. The rifling is always putting a fresh bite on the bullet".

The intention is to drive it hard, and the "fresh bite" made it a variable to me. As the bullet isn't made yet, it's a bit of an experiment, and reducing variables is on my mind.

Also, decided against coating the barrel as it's also adding another variable.

"Rock" having the slight gain I don't have an issue with. Presumably you mean Rock Creek, and they turned us down-can't remember now if it was barrel length (31" finish) twist, or combination of the 2.

Bartlein is charging extra for the tooling change required.

 

[lacajun]

interesting thread

 

[J E Custom]

Very interesting so far !! Keep them coming.

I to have my likes and dislikes based on building many rifles and seeing the results first hand.

I like three basic rifling grove counts and rifling designs. The first is 3 grove for ultra fast small caliber cartridges. With the right bullets (Light), they are amazing. But they are hard on heavier bullets or bullets with thin jackets.

For the mid calibers, 7mm to .338 I use 4,5 or 6 grove for consistent engraving of the bullet and good all round accuracy.

For the Big bores, .375 to .577 I like the 8 grove barrel because of the very heavy bullets and the positive engraving without jacket separation from the bullet core. Twist rates do have a bearing on the performance of all types of rifling, but we can discuss that on the next thread. (It will probably get more different opinions).

As to the design of the rifling, I haven't seen any difference in accuracy
of a ratchet, 5r or conventional design as long as you buy a premium barrel. The same thing goes for the cut rifling versus the buttoned rifling as long as they were both made properly and hand lapped, both types perform equally well. Some designs clean easier and foul less, but if they are properly lapped I have not seen any trend favoring one over the other.

When ordering a new barrel, I prefer to chose the rifling design and count first based on the type of bullet and caliber, then based on the bullet weight and shape (Design) and jacket type I will decide on the optimum twist rate that will complement the rifling design and the overall accuracy potential.

So in my opinion and experience, if you chose the optimum grove design and twist rate for your use, and a premium barrel combined with excellent smithing success is very possible.

J E CUSTOM