stabillity question.

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  • Last Post 05 August 2012
adrians posted this 03 August 2012

Morning ladies and gents ,

Soon i will be taking possession of a Krag sporter and was curious about bullet choice for a barrel which has been cut down from original issued length.

The rifle in question is an 1896 ( made in 96) and the rifle is sported , nicely i might add, but it's barrel length is only 22” long.

I have various bullet moulds for the 30 cal including 311284 ans 316299 , 308 291, 3114, etc , but would a severely cut down barrel stabilize the heavier ,longer 311284 and the 299's.

I don't wish to shoot this rifle above 1500--1600 fps (my right shoulder is shot) and was just curious if i can expect decent results using these heavyweights in a short barrel at low vel.

Like i said i haven't got the gun home yet so no bore slug yet , but I'm just curious.

ANY info would be great as this is my first 30-40,,,,,,,,, and i can't contain myself the wait is killing me.... sorry if this question is redundant as i haven't done a search here yet on the Krag.

have a groovy Friday, :coffee

 

 

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72coupe posted this 03 August 2012

I'm not an expert on this subject but I think the twist rate of the rifleing has more effect than length. 22 inches should be more than adequate length if it is still the original barrel. I am pretty sure the original twist rate was 1turn in 10 inches.

I have a Remington 40X with a twist of 1 in 12 and it will not stabilize the 314299 that I have. It shoots decent groups but all the holes are oblong.

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John Alexander posted this 03 August 2012

I am not an expert either but 72 coupe is right the effect of twist on stability is much more important than lower velocity as in from a shorter barrel.

I have always found the effect of velocity on stability of bullets that were too long to be small.

I don't believe there is any effect at all directly on barrel length -- only a bit as it allows higher velocity.

The Krag was designed to shoot 220 grain bullets and there were Krag carbines.

John

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Wayne S posted this 03 August 2012

The twist in the bbl. determines the stability, and the length of the  bullet determines if it will stabilize in that twist .  Take a cleaning rod that the rod is able to turn within the handle.Attach a new bore brush or wrap a cleaning patch around an old brush, the idea is a tight fit within the bore. Set it up to drag the brush  out the muzzle, when the brush  offers resistance, put two marks on the rod, one running left to right on the rod and a 2” mark on the  rod, from the muzzle toward you, continue to pull the rod out till the  long mark makes one full turn. Measure the distance. That number in inch's is the twist; 1-10, 1-14” ect.  Then, search” stability programs"

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Ed Harris posted this 03 August 2012

I shoot a 220-gr. plainbased CBE bullet, originally designed for the .303 British, in my Krag sporter with fine results using 12 grs. of #2400.  Bullet I use is this one, but without the GC heel.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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codarnall posted this 03 August 2012

Not only it is a function of bullet weight/length cut off barrels can be problematic due to shock traveling down the barrel when firing. Most folks call it barrel whip which suffices to explain the issue. The shooter may really have to tune the velocity to the barrel. It's studied and tabulated/graphed in “Rifle Accuracy Facts” Just a thought.

Charlie

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John Alexander posted this 03 August 2012

For any given barrel contour the barrel becomes stiffer the more you cut off the muzzle end the stiffer barrel resuces the amplitude of the barrel vibrations.

To the extent that this effect is important to accuracy in cast bullet shooting compared to all the other things we have to worry about, shortening the barrel from the muzzle end should generally reduce the problem.

I have never heard it claimed that barrel vibrations have any effect on stability and cannot see why it would -- even in theory.

Twist vs. bullet length is the major issue just as Wayne S. noted above. Velocity is a minor factor by comparison.

Adrian can quit worrying about barrel length affecting stability.

John

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adrians posted this 03 August 2012

:^:   Thank you all for your replies,

 I think my question has been answered by you folks , and when the rifle gets here i will try your load Ed ( 12 --- 2400) with the 311284 and the 316299 ,sized accordingly.

Ed, what velocity does that load produce ?.

thanks and have a great weekend.

Adrian..:thumbsup:

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ubetcha posted this 03 August 2012

Isn't there a formula for figuring out the weight of a bullet to twist ratio? I think it's called the Greenhill Formula.How accurate it is I don't know.I believe its in Joe Brennen's book

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Ed Harris posted this 04 August 2012

adrians wrote: :^:   Thank you all for your replies,

 I think my question has been answered by you folks , and when the rifle gets here i will try your load Ed ( 12 --- 2400) with the 311284 and the 316299 ,sized accordingly.

Ed, what velocity does that load produce ?.

thanks and have a great weekend.

Adrian..:thumbsup: About 1200 fps.  Haven't chronographed it, but it has a slight “crack” to it, though doesn't lead in soft 10 BHN alloy.  Use the same charge in .303 British.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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adrians posted this 04 August 2012

That sounds like about what I'm looking for Ed, thanks.

As a bonus you use the same load in the 303's ,,,,great ,i have a couple of those I'll try it in .

The 316299 was acquired specifically for the “larger than spec Brits” i have.

weekend is here so have fun,,, I'm casting up a few but heck it's hot here.... oh well.:shock: 

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CB posted this 04 August 2012

adrians Velocity has a part of bullet/twist factor. I have dropped velocity down to 1,400fps with 220gr CBs in a 1-10 twist barrel and had the CBs tipping at 200yds on target with accuracy loss, but the same load shot well out to 100yds........Dan

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adrians posted this 05 August 2012

Dan Willems wrote: adrians Velocity has a part of bullet/twist factor. I have dropped velocity down to 1,400fps with 220gr CBs in a 1-10 twist barrel and had the CBs tipping at 200yds on target with accuracy loss, but the same load shot well out to 100yds........Dan

Dan, on a side note,, in a couple of weeks we are closing on our “city” house and moving up country to a 10 acre place which is all hardwoods so i think a 100yd shooting lane is all i have,( i've already walked the land and have a idea of where it's going to be,).

1200=== 1400 fps    at    50===100 yds ,,,,I'll be in heaven.

take care guy's and thank you all for you insight and advice it's much appreciated..:D 

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