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Dimitri Super Member
Joined: Nov 25, 2005 Posts: 5944
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Posted: Fri Oct 27, 2006 10:16 am Post subject: Re: Keyhole target hits |
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Here is a picture of keyhole targets I got from another forum,
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My friend, who lives in Germany, recently bought a milsurp Steyr (M1903) in 6.5X54 MS. The only ammo he could find, for now, was a 20+ year batch made by RWS.
Below, is a pic of his first 100m "grouping".Would you say that it's time for a new barrel, or should he try shooting again, with another brand of ammunition? |
Dimitri
_________________ A thousand hills, but no birds in flight, ten thousand paths, with no people's tracks. A lonely boat, a straw-hatted old man, fishing alone in the cold river snow. |
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temmi Rookie Member
Joined: Jun 16, 2006 Posts: 12
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Posted: Fri Oct 27, 2006 2:10 pm Post subject: Re: Keyhole target hits |
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Had a 22LR rem keyhole every shot... I sent it back to the factory... Rem sent me a new one.
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SwampFox Super Member
Joined: Jul 15, 2005 Posts: 1040 Location: Destin, Florida
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Posted: Fri Oct 27, 2006 3:43 pm Post subject: Re: Keyhole target hits |
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I vote for new barrel.
Ed
A Barrel
_________________ The inherent vice of capitalism is the unequal sharing of the blessings. The inherent blessing of socialism is the equal sharing of misery.
-Winston Churchill |
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PaulS Super Member
Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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Posted: Sun Oct 29, 2006 4:28 am Post subject: Re: Keyhole target hits |
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You may not need a new barrel. Or you might need to recrown the barrel that you have. A damaged crown can make bullets tumble in flight too. Most any gunsmith should be able to tell you if a barrel needs a new crown. If those bullets were 220 grain RN bullets they could be too long to stablize in your barrel. Get a box of 150 or 165 grain bullets and shoot them. if you get similar results then yes, its time for a new barrel. The rifling twist in most 308 is optimized for 150 grain bullets. They are also the bullets with the highest impact at most shooting ranges. Most of the 308 rifles will stablize bullets from 125 to 180 grain range and bullets heavier than 180 grains lose a great deal of velocity at the muzzle du to a lack of space for the powder to drive them at reasonable speeds.
Try the lighter bullets first - then decide whether you need a new barrel, a recrowning job, or just ammo that better matches your rifles twist rate.
_________________ Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads |
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BLOC Rookie Member
Joined: Nov 10, 2006 Posts: 1
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Posted: Fri Nov 10, 2006 11:53 pm Post subject: Re: Keyhole target hits |
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Oh yes . . .
I have a 6 mm Remington, with a Schneider bbl having a 1:12 twist on a Mod. 98 Mauser, built especially to stabilize light, short bullets. It does that with elan -- my best group was 0.08 inches at 100 yards (3 rounds) using a 55 gr CT Bal Silvertip (I framed the target). And I can often shoot 0.5 MOA or better with lighter bullets when I'm "on."
But when I tried the 95 gr. Nosler BT, or anything heavier (and longer), I was lucky to hit the paper at 100 yards, and if I did, the bullet keyholed. It will shoot the 87 Hornady okay, but that seems to be the limit.
bloc
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ellmont Rookie Member
Joined: Nov 08, 2006 Posts: 1
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Posted: Wed Nov 29, 2006 4:46 pm Post subject: Re: Keyhole target hits |
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Keyhole - hell yes, if you're a reloader you can accomplishs this very easily - I shoot 45-70 - bought a new winchester - uberti high wall and shot the rounds I was using for my trapdoor - 405 RNFP, with Trail Boss powder - don't have the powder data with me - keyholed in the highwall at 100 yds. - could actually hear the bullet hit the target and backing - kind of told me the charge was too light - got a lighter bullet - 350 gr., worked better - got round holes but accuracy was not good - went back to 405 gr. and some IMR 4831 - velocity over a 1000 fps. - good accuracy and no keyholes - the moral - you keyhole if your powder is too light - try a bigger charge - also Trail Boss is really not designed for high velocity.
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Arron Super Member
Joined: Nov 20, 2006 Posts: 352 Location: Cen.Iowa, by way of SWIowa
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Posted: Tue Dec 05, 2006 1:25 am Post subject: Re: Keyhole target hits |
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The only time I have had any type of keyholing was with some out of tune arrows I was using along time back. I have heard of this happening but not seen it with my own eyes. Typically this is how rifling works - the heavier the bullet the faster the twist you need to get the bullet rotating on it's axis. The lighter the bullet then the less rifling you need to get the same thing. If you are using the wrong bullet for the twist and vice versa it will throw off the rotation and cause ALL sorts of trouble. Most "factory" rifling is cut to match the middle type weights for caliber so that is where you should probably be especially with factory loadings. Sometimes you can also vary the muzzle velocity or just change the shape of the bullet and it will settle down a little, but if your rifle does not like something there are enough components out there you can most likely find one that will work. A messed up crown can also cause this as the bullet get caught on a rought patch when the rest of the bullet is trying to exit so it throws the bullet off. Another is the vibration is out of sync with the load, there is not much you can do about this other than change components and try again or get a BOSS. I would love to have one of these!
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Pumpkinslinger Super Member
Joined: Sep 22, 2007 Posts: 5001 Location: NC foothills
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Posted: Tue Oct 02, 2007 1:27 am Post subject: Re: Keyhole target hits |
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I've seen a .22-250 keyhole when firing a 70 grain bullet with a starting load. Combination of long bullet, relatively low velocity and slow twist.
My reporduction P1853 Enfield keyholed with Minie balls that were cast too hard. The base wouldn't expand to grip the rifling.
My brother had a 9mm pistol that would keyhole at abuot 15 yds but I never got to figure out why, he took it back to the dealer. I think he said it wasn't rifled.
_________________ Mike
"I ain't no better than anybody else, and there ain't nobody better than me!" Ma Kettle |
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chambered221 Super Member
Joined: Aug 17, 2007 Posts: 3455 Location: Lost for good !!!
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Posted: Tue Oct 02, 2007 6:35 pm Post subject: Re: Keyhole target hits |
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I have slug gun that uses a 5 inch rifled choke tube, Lets just say it is pretty paticular as to what ammo I can feed it. The first 3 brands I tried all keyholed. Those that followed were not that much better. Someone then told me to try the Remington copper solids. Could not belive what my eyes were seeing. 3 shots, 100 yards, all touching in clover leaf fashion. I just knew it was a fluke. It wasn't. I left the range and went right back to the store I bought the first 2 boxes and left with evry 12ga. copper solid they had. Turns out only that one lot number was as good as that first group. The other 2 lot numbers shot good but nothing like the first. Remington has since changed something in that ammo and I had to quit using it. Federal has a slug designed for rifled tubes that has done well for me of late. It will hit a 3 inch sticker at 100 yards pretty much evry time.
When ever anyone talks about twist rate they usually refer to a bullets weight range that goes with it. This isn't wrong, but the bearing surface length of a bullet is the important factor that is usually overlooked.
A hunter class benchrest shooter by the name of Robby Robinett did some in depth studies on this issue. He found that the length of the bullet was one of the most important factors regaurding twist rates. His findings led him to come up with combinations that his barrel maker even questioned him on what he was doing. All said and done Robby started winning and has become the guy to beat in his sport. His findings are now the standards (for Hunter Class Benchrest) for building a gun to win with.
Robby Robinett is also the owner of BIB Bullets.
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vint2 Super Member
Joined: Nov 18, 2005 Posts: 1216 Location: Iowa
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d_hoffman Super Member
Joined: Feb 13, 2007 Posts: 696 Location: Chillicothe, Ohio
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Posted: Tue Oct 02, 2007 9:47 pm Post subject: Re: Keyhole target hits |
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I've heard that some of the old milspec ammo was designed to tumble. That way, when it hits the enemy it comes out in a different direction ie hits your right shoulder and comes out your @$$.
_________________ The best form of gun control...aim straight!!! |
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vint2 Super Member
Joined: Nov 18, 2005 Posts: 1216 Location: Iowa
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Posted: Wed Oct 03, 2007 4:50 am Post subject: Re: Keyhole target hits |
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Milspec is some really nasty sounding stuff!!
_________________ All it takes for evil to prevail is for good men to do nothing! |
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FALPhil Super Member
Joined: Aug 18, 2007 Posts: 377 Location: Dixie
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Posted: Wed Oct 03, 2007 10:43 am Post subject: Re: Keyhole target hits |
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guncollector wrote: |
I have a fast twist AR15 (1:8) that I shoot mostly 77 gr SMK through. When trying to shoot some 55 grainers, I did get some keyholing. I always thought it was supposed to happen the other way around - with barrels that have too slow of a twist for the bullet. I guess it works both ways. |
What you were probably experiencing was bullets disintegrating, especially if you were using thin jacket varmint bullets in a fast twist. I have seen this a couple of times. The way to test for it is to put another target about 20 yards behind the first one and check for multiple holes per shot.
I once had a No 4 Mk 1 that keyholed. There was a bulge in the bore that caused it.
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vint2 Super Member
Joined: Nov 18, 2005 Posts: 1216 Location: Iowa
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Posted: Wed Oct 03, 2007 12:00 pm Post subject: Re: Keyhole target hits |
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It is absolutely amazing what a person can learn in these forums!!!!
I have found this discussion very enlightening!!
_________________ All it takes for evil to prevail is for good men to do nothing! |
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Dimitri Super Member
Joined: Nov 25, 2005 Posts: 5944
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Posted: Wed Oct 03, 2007 3:12 pm Post subject: Re: Keyhole target hits |
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d_hoffman wrote: |
I've heard that some of the old milspec ammo was designed to tumble. That way, when it hits the enemy it comes out in a different direction ie hits your right shoulder and comes out your @$$. |
Ammo of a thick enough jacket will yaw (tumble) as shown:
However rounds like the 223Rem with thinner jackets will fragment and yaw:
And a .223Rem but in Soft Point form:
And the German 7.62mm NATO Rounds that fragment like 223 rounds because of the thin jackets compared to a fired American 7.62mm NATO round:
As you can see the bullet breaks in half after yawning for abit and then the back fragments while the front keeps pushing forward.
Now some bullet designs are designed to yaw more then normal, by having a pocket of air or lighter material in the tip of the bullet like the Russians did:
South African 303British Ammo with a lighter aluminum tip:
And finally British 303British Ammo with a wooden tip:
Dimitri
_________________ A thousand hills, but no birds in flight, ten thousand paths, with no people's tracks. A lonely boat, a straw-hatted old man, fishing alone in the cold river snow. |
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