Keyholing

The_Vigilante · June 4, 2009, 11:42 PM

I am having problems with a lot of my reloads keyholing and need to eliminate this. I use 147g LFP, mixed cases, 3.6g of VV N320, and COL of 1.135. How can I troubleshoot this problem to isolate and eliminate the problem? Thanks

Dannyl · June 4, 2009, 11:55 PM

Hi,

Key holing is caused by bullets that are not stabilized and therefore "tumble" as they fly.

I have seen this happen in various occassions.

in one instance I saw this happen with a GALIL assault rifle when I was in the IDF, the gunsmith inspected the weapon and determined that the barrel was worn and it had to be replaced.

Many years later, I replaced the barrell of a browning HP, and after experiencing key-holing, I took it to a gunsmith who slugged the barrel and determined that it had a diameter of 0.356, while the bullets ( cast lead) that I was using were 0.355.

I suggest that you ( or a gunsmith)check the diameter of your barrel and bullets, this should give your he answer.

Regards,

Danny

Sam06 · June 5, 2009, 12:06 AM

What Caliber?? What gun are shooting them out of?? Come on if you want an answer we need some info like:
1. Gun type and twist rate
2. Caliber
3. Range your shooting

FrankenMauser · June 5, 2009, 12:11 AM

Dannyl makes a good point. Although there are many things that can cause keyholing; barrels can be a big contributor.

I have a Taurus .380 Auto (regret the purchase...), that suffers the problem he described.
After seeing some very alarming wear patterns in the barrel, I slugged it. It turned out to be a .357" x .358" x .359" bore. (Groove measurements) The .355"-.356" bullets were barelly being engraved by the rifling, let alone obturating to fully fill the grooves.

As you may have guessed, since I am posting this; accuracy was a joke, even without keyholing.

B.L.E. · June 5, 2009, 06:14 AM

A bullet too long (heavy) for the rifling twist will not stabilize but I don't think that is your problem with a 147 grain bullet in what I assume is either some 9 mm or .357/.38 caliber.
You may have a bore so leaded that the rifling isn't spinning the bullet anymore. I have a .357 revolver that simply will not digest swaged lead bullets without leading up the barrel so bad that the bullets start keyholing.

If the bullets are too small to fill the grooves in the rifling, the resulting blowby will lead a barrel.

Dannyl · June 5, 2009, 06:24 AM

Hi,
Leading is always a problem, and one must use lead remover, a bronze brush and lots of elbow grease, and clean it properly after each time we shoot ( I do).
However, I think that it will take many ( thousands) bullets fired before the lands are filled to such extent, and it will prossibly manifest itself in pressure problems as well.

147 Gr is not too heavy for 9mm of .357, I use 147 all the time with my browning for pin-shooting, and for the 357 I use 180Gr ( all cast bullets)

I get very good accuracy in both instances.

It all goes back to a lose fit of a bullet in the barrel.

Regards,
Danny

Russ5924 · June 5, 2009, 01:59 PM

It would be nice to know the make model and caliber with out guessing

Nnobby45 · June 5, 2009, 02:08 PM

Quote:

What Caliber?? What gun are shooting them out of?? Come on if you want an answer we need some info like:
1. Gun type and twist rate
2. Caliber
3. Range your shooting

Quote:

It would be nice to know the make model and caliber with out guessing

All of the above, and I'll add that a combination of LOW VELOCITY AND SHORT BARREL can also result in insufficient spin to stabilize some heavier bullets.

CorBon's standard velocity .38 Special DPX is an example of that. In snubbies, the +P version has enough velocity to stabilize the bullet. I've heard reports that in SOME snubbies, the standard velocity bullet can keyhole to a small extent.

petemo · June 5, 2009, 03:14 PM

Well I had the problem when I was using cast bullets that were the wrong diameter for the barrel. I had a 45 70 and was using a bullet can't recall how many grains. The bullet was just too small for the barrel and down range it was anybody's guess how the bullet hit the target, sideways , straight or even backwards for all I know. Changed to another bullet a few thousands larger and all was fine

petemo · June 5, 2009, 03:45 PM

At that time I was casting and sizing my own bullets. I picked up a mold at a gun show. The bullet was long and heavy, heavier than standard 405. Anyway when I put it through the sizer luber it slid through pretty easy and the lube instead of being in the groves was also smeared on the lands. Well I guess that should have told me right then something was wrong but I was not very savy about the whole thing then. When I changed to a mold a few thousands larger everything worked the way it should. Lube was in the grooves not on the lands and the key hole problem disappeared,
A bullet not being pushed hard enough will key hole. I have tried sub sonic loads to keep noise down and sometimes they will keyhole.
Anyway be safe

The_Vigilante · June 5, 2009, 07:16 PM

Thanks for all of your comments. Sorry for the omission of needed info. OK, I am shooting an CZ SP01 Phantom 9mm. Rate of twist is 1:9.7". Bullets are lead flat point 147g with Brinell of 18 and diameter of .356. Range shooting is IDPA anywhere from 10-30'. Is too much crimp a cause of keyholing? Powder as previously indicated is 3.6g of VV N320. I have used other powder ( Bullseye, WSF, WST) and have experienced keyholing to some extent.

a7mmnut · June 5, 2009, 07:34 PM

While 6 grooves may or may not stabilize better than 4, I'd switch to 115's and fire away. 124's may be better?

-7-

June 4, 2009, 11:42 PM	#1
The_Vigilante Senior Member Join Date: May 17, 2008 Location: Far West Texas Posts: 200	Keyholing I am having problems with a lot of my reloads keyholing and need to eliminate this. I use 147g LFP, mixed cases, 3.6g of VV N320, and COL of 1.135. How can I troubleshoot this problem to isolate and eliminate the problem? Thanks __________________ The_Vigilante Keeping the streets safe! A man can never own enough guns!

June 4, 2009, 11:55 PM	#2
Dannyl Senior Member Join Date: April 20, 2009 Location: Cape Town - South Africa Posts: 627	poor fit of bullet to the barrel Hi, Key holing is caused by bullets that are not stabilized and therefore "tumble" as they fly. I have seen this happen in various occassions. in one instance I saw this happen with a GALIL assault rifle when I was in the IDF, the gunsmith inspected the weapon and determined that the barrel was worn and it had to be replaced. Many years later, I replaced the barrell of a browning HP, and after experiencing key-holing, I took it to a gunsmith who slugged the barrel and determined that it had a diameter of 0.356, while the bullets ( cast lead) that I was using were 0.355. I suggest that you ( or a gunsmith)check the diameter of your barrel and bullets, this should give your he answer. Regards, Danny

June 5, 2009, 12:06 AM	#3
Sam06 Senior Member Join Date: May 19, 2008 Location: Fayettenam Posts: 1,086	What Caliber?? What gun are shooting them out of?? Come on if you want an answer we need some info like: 1. Gun type and twist rate 2. Caliber 3. Range your shooting __________________ The two most abundant elements in the universe are hydrogen and stupidity.

June 5, 2009, 06:24 AM	#6
Dannyl Senior Member Join Date: April 20, 2009 Location: Cape Town - South Africa Posts: 627	bullets tumbling Hi, Leading is always a problem, and one must use lead remover, a bronze brush and lots of elbow grease, and clean it properly after each time we shoot ( I do). However, I think that it will take many ( thousands) bullets fired before the lands are filled to such extent, and it will prossibly manifest itself in pressure problems as well. 147 Gr is not too heavy for 9mm of .357, I use 147 all the time with my browning for pin-shooting, and for the 357 I use 180Gr ( all cast bullets) I get very good accuracy in both instances. It all goes back to a lose fit of a bullet in the barrel. Regards, Danny

June 5, 2009, 01:59 PM	#7
Russ5924 Senior Member Join Date: February 18, 2005 Posts: 1,874	It would be nice to know the make model and caliber with out guessing __________________ Russ5924

June 5, 2009, 12:11 AM	#4
FrankenMauser Senior Member Join Date: August 25, 2008 Location: In the valley above the plain Posts: 13,424	Dannyl makes a good point. Although there are many things that can cause keyholing; barrels can be a big contributor. I have a Taurus .380 Auto (regret the purchase...), that suffers the problem he described. After seeing some very alarming wear patterns in the barrel, I slugged it. It turned out to be a .357" x .358" x .359" bore. (Groove measurements) The .355"-.356" bullets were barelly being engraved by the rifling, let alone obturating to fully fill the grooves. As you may have guessed, since I am posting this; accuracy was a joke, even without keyholing.

June 5, 2009, 06:14 AM	#5
B.L.E. Senior Member Join Date: December 20, 2008 Location: Somewhere on the Southern shore of Lake Travis, TX Posts: 2,603	A bullet too long (heavy) for the rifling twist will not stabilize but I don't think that is your problem with a 147 grain bullet in what I assume is either some 9 mm or .357/.38 caliber. You may have a bore so leaded that the rifling isn't spinning the bullet anymore. I have a .357 revolver that simply will not digest swaged lead bullets without leading up the barrel so bad that the bullets start keyholing. If the bullets are too small to fill the grooves in the rifling, the resulting blowby will lead a barrel.

June 5, 2009, 03:14 PM	#9
petemo Member Join Date: February 20, 2006 Location: Georgia Posts: 49	key holing Well I had the problem when I was using cast bullets that were the wrong diameter for the barrel. I had a 45 70 and was using a bullet can't recall how many grains. The bullet was just too small for the barrel and down range it was anybody's guess how the bullet hit the target, sideways , straight or even backwards for all I know. Changed to another bullet a few thousands larger and all was fine

June 5, 2009, 03:45 PM	#10
petemo Member Join Date: February 20, 2006 Location: Georgia Posts: 49	Forgot to mention At that time I was casting and sizing my own bullets. I picked up a mold at a gun show. The bullet was long and heavy, heavier than standard 405. Anyway when I put it through the sizer luber it slid through pretty easy and the lube instead of being in the groves was also smeared on the lands. Well I guess that should have told me right then something was wrong but I was not very savy about the whole thing then. When I changed to a mold a few thousands larger everything worked the way it should. Lube was in the grooves not on the lands and the key hole problem disappeared, A bullet not being pushed hard enough will key hole. I have tried sub sonic loads to keep noise down and sometimes they will keyhole. Anyway be safe

June 5, 2009, 07:16 PM	#11
The_Vigilante Senior Member Join Date: May 17, 2008 Location: Far West Texas Posts: 200	Keyholing Thanks for all of your comments. Sorry for the omission of needed info. OK, I am shooting an CZ SP01 Phantom 9mm. Rate of twist is 1:9.7". Bullets are lead flat point 147g with Brinell of 18 and diameter of .356. Range shooting is IDPA anywhere from 10-30'. Is too much crimp a cause of keyholing? Powder as previously indicated is 3.6g of VV N320. I have used other powder ( Bullseye, WSF, WST) and have experienced keyholing to some extent. __________________ The_Vigilante Keeping the streets safe! A man can never own enough guns! Last edited by The_Vigilante; June 5, 2009 at 07:18 PM. Reason: keyholing

June 5, 2009, 07:34 PM	#12
a7mmnut Junior member Join Date: February 27, 2009 Location: NC Foothills Posts: 1,150	While 6 grooves may or may not stabilize better than 4, I'd switch to 115's and fire away. 124's may be better? -7-