Choke in rifles

[TwoRivers]

Rifle barrels are not choked, though with the old cut rifling methods a slight choke would form as the cutterhead was emerging from the barrel, and was no longer fully supported by the bore.  This section was then normally cut off; though some makers may have claimed that leaving it on was an improvement. During black-powder breechloader days tapered rifling of various forms was much more common.  Modern rifling methods vary in the result, hammer-forging gives a slighter tighter bore as the barrel walls get thinner, the bore gets ever so slightly narrower towards the muzzle in a tapered barrel.  With button rifling the opposite occurs, the bore gets slightly wider with the taper. The Brits actually deepened the grooves towards the muzzle of their Lee-Enfields to reduce friction and increase velocity; until they dropped the practice in 1915 as a manufacturing expedient.  With Grumpy lurking in the shadows, I'll withold my judgement of the sanity of that practice.  Cheers.

[MoA]

I'll withold my judgement of the sanity of that practice.  Cheers.

Some rifle barrels are choked ever so slightly. These typically tend to be very high end .22LR bench rest guns, which also incedeltally follow a two grove pattern. The current theory is that it adds a degree of stability to the soft lead rounds.

With the larger calibers this doesnt really hold true since copper is a much stronger material. Simillar effects are garnered with the use of Moly coated bullets, which provide a more snug fit, higher velocities while having the paradoxical effect of lowered CUP pressures.
But most of this does not really have a bearing except in the rarified circles where a difference of .01 inches would make the difference between a win and a loss in a compitition.

[TwoRivers]

MoA: Moly coating reduces friction, period. Nobody shoots solid copper bullets in bench rest. Bench rest is shot with centerfire catridges, with rimfire you have no control over cartridge quality. Pressure readings are determined long before the bullet would get to the choke; and the CUP method, in any case,only gives an instantaneous indication of the pressure at the chamber. It's the spin that's imparted by the rifling that gives the bullet it's stability. It was theorized during WWII, that having only two grooves lessened the engraving effort, and thus reduded pressure. However, those were very inconclusive tests run to see whether ommitting two of the standard four grooves, thus increasing cross-sectional bore area, would increase pressure dangerously. With the barrels used, they actually got slightly less pressure. If a "choked" two-groove barrel had advantages, that's all you would see. Lastly, would you be kind enought to tell us who makes those magical choked two-groove barrels? The best I can find among our barrel makers is a three-groove. The less bullet distortion by the rifling, the more accurate it will be. That's the theory. Yet oval bore rifling has been around for a long time, and hasn't caught on, despite other advantages. Cheers

[MoA]

MoA: Moly coating reduces friction, period. Nobody shoots solid copper bullets in bench rest. Bench rest is shot with centerfire catridges, with rimfire you have no control over cartridge quality. .................. Yet oval bore rifling has been around for a long time, and hasn't caught on, despite other advantages. Cheers

1. Did I say solid copper bullets? Or did I just say copper? As in copper jacketed. Some shooters have experimented with solid bullets, without much luck.
2. No one shoots .22LR benchrest? Well I am certain the ARA et al. will cease its activities immediately, and shooters like Joe Friedrich will immediately switch to centerfire.
3. The leading producer of two groove barrels is a small outfit called Benchmark. I could put you in touch with Bill Myers, Bison Barrels is again in the top end for these. Lija (though they are much better known for centerfire barrels)will cut you one as well, as will I believe a number of bespoke shops in the EU using mainly blanks from Walther Lothar.
4. You do have more control over quality rimfire ammunition than you would believe. Most people who do shoot rimfire benchrest tend to test multiple lots of ammunition from Lapua and Eley for accuracy and consistency and then select a particular lot for a given barrel. There are variances even between consecutive lot numbers of Eley Tenex, especially between ammunition produced on different machines.

as for moly I could sit and debate it with you for hours. But hey internet shooting is easy. Realworld is a little different.

[TwoRivers]

MoA: Friend, you should live so long as to be able to shoot half as much as I have. No, the ARA is perfectly free to keep pretending, all fringe groups are welcome, they all contribute knowledge and innovation. They are as welcome as any other shooter or gun enthusiast, whether they have a different perspective than I, or not. Of course you can keep testing different lots of .22 RF ammo from different makers, but that's not what I would call control over your ammo. As to moly-coating, indeed we could debate that for ever. Some shooters swear by it, others at it. Some barrels do well it, others poorly. Some bullet makers have kept it, others have dropped it. "It's a matter of opinions, some like apples, some like inions". Bench rest shooting per se can be considered a form of ammunition testing; and .22 RF bench rest to the extreme. And didn't I say "as long as it is fully stabilized" ? Cheers.

[MoA]

Well thankyou for wishing me luck in shooting, I certainly hope I continue to have the opportunities to shoot as I do currently.
You could call bench rest a form of testing ammunition, but there is a lot more to the discipline than just ideal loads. I do shoot both bench and practial long range when I get the opportunity.
Mostly for fun. Wierdly its my wife who is the better shot, and sticks primarily to ARA style shooting.

Who knows we might have the opportunity to shoot together some day.. cheers.

[TwoRivers]

Well, I certainly hope that you will continue to have that opportunity; being able to enjoy your sport, and the fellowship and cameradarie that comes along with it. (Even at the fringes.) Don't know what to say about your wife outshooting you, though. But I'm sure your fellows have enough to say about. Every man should be that lucky! Never been too keen on any sport where I need a cart to carry my equipment, though. Cheers.