About barrels

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About barrels

Postby dedseven » Mon Oct 01, 2007 1:37 am

Greetings to all. I am a life-long firearms enthusiast who is just now developing an interest in BPCR shooting. I am also a machinist working in a gun shop handling the reboring and barrel making chores. I have lurked in these forums for a while in an attempt to lean something and now I want to ask a question or two. I want to put together a rifle to use in our local long range matches (steel targets out to about 1200 yards). I will be making my own barrel and I have a question about what rifling form is the best for BPCR use. We cut rifling using single point tooling which gives me the ability to alter the geometry of my bore fairly easily. I have read that some people believe a barrel with narrow lands and wide grooves is superior. I’ve also read that square cornered grooves are best avoided. So please let a beginner know what you think. Shallow grooves or deep? More or fewer grooves? Wide lands or narrow? We can’t cut gain twist rifling yet so that will have to wait but I would be eager to hear what you think about that too, and why. I’m sure there is a lot I can learn from your collective experience so please share it!

Allen
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Postby martinibelgian » Mon Oct 01, 2007 6:33 am

My opinion - and worth what you paid for it:
- Shallow rifling
- Wide grooves
- Rifling form? Nor real favourite, but I am rather partial to Metford segmental rifling (mine a Snover), even though my Eichelberger with traditional rifling works extremely well too.... And I would LOVE to experiment with Lancaster oval-bore rifling!
- smooth barrel, preferably lapped
- 34" for LR work

Just my opinion, and opinions.... you know what they say.
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Postby ssdave » Mon Oct 01, 2007 8:40 pm

I'm always ready to offer an opinion, for what it's worth.

If you have the means to do whatever you want, I think that the best configuration would be narrow lands, wide grooves, fairly shallow rifling. About 6 or 8 lands/grooves. Grooves would be cut so that there were rounded corners, and I would use Pope style rifling where just the corners of the grooves would be cut, and the middle of the groove would be at bore diameter. Lap the reamed bore absolutely smooth before starting to cut, and lap in a slight taper towards the muzzle, so that the bore tightens as the bullet works its way down the barrel. Lightly lap the completed barrel, just enough to get out any surface rougness caused by the rifling cutting, but not enough to round over the top of the lands.

The rationale behind all this is that the less you deform a bullet, the more likely it is to fly straight. Narrow lands will deform the bullet less, and cutting the grooves so that the center is at bore height seals the bullet tighter without having to deform it into the groove.The choke bore continuously tightens up the fit, so that the bullet seats tight all the way to the muzzle, so that gas blowby doesn't cut and start leading. The rounded corners leave less place for fouling or leading to accumulate, and clean easier.

Hope this helps!

dave
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Postby deerhuntsheatmeup » Fri Oct 05, 2007 5:58 am

FWIW

I would make it just exactly like Krieger makes there barrels.

Best, Barvid
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Re: ....

Postby Harry Eales » Wed Oct 24, 2007 3:27 am

deerhuntsheatmeup wrote:FWIW

I would make it just exactly like Krieger makes there barrels.

Best, Barvid


Hello Barvid,

This link may help you, :-

http://www.kriegerbarrels.com/RapidCat/ ... anyId=1246

Harry
Never kick a sleeping Lion in the balls, unless you have a foolproof way of dealing with his teeth.
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Postby deerhuntsheatmeup » Tue Oct 30, 2007 3:32 pm

Harry,

I have looked the Kreiger site over alot. It is the barrel of choice for me on any rifle I have built except Shiloh. I have a HW that is a 17" twist in 45-70 and it is the easiest rifle I have ever seen to develope an accurate load for. The rifle likes any powder and bullet combo I feed it.

I have a 1.3" 17" twist round chrome moly barrel on order that I was quoted 16-20 weeks lead time. I ordered it just to have a spare, so to speak.

So many rifles, so little time!

Best, David B
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Postby fatman4570 » Mon Nov 05, 2007 7:14 pm

Ditto what David and Harry said. Straight uniform bore, no taper. At this point you should know what type (shape,length,weight) of bullet you are going to use. It will determine the rifling twist you can choose. You have a chance to put the horse before the cart. :lol:
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Postby JSU » Tue Nov 13, 2007 8:29 am

Do a little research and have a look at what is called "Pope Rifling" as done by Harry Pope. Even Krieger offers a variant of this profile.

It is probably harder to do than some of the more prevalent profiles, but it did help anchor the reputation of Harry M. Pope as perhaps the best barrel maker of his time.

---Steve
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Postby martinibelgian » Tue Nov 13, 2007 12:21 pm

Hmmmm.... As much as I do respect Pope, most of his work was for 200yd schuetzen shooting - not for LR BPCR. For that purpose, I would rather look towards W.E. Metford as an example, and the Metford segmental rifling barrels, as made by Ron Snover. What is best for 200 isn't necessarily best for 1,000...
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