Keyholing.

PinnedAndRecessed · August 1, 2005, 10:50 AM

I recently bought a pre 27 S&W with a 3.5 inch barrel. I worked up some loads using a 125 grain plated bullet ahead of 6 grains Unique. But at 7-10 yards some of the rounds keyholed. Why?

Russ5924 · August 1, 2005, 11:33 AM

I would say better check your barrel for fowling lead or copper.That load should have been OK at that range. You are getting even powder in all cases ??????

HSMITH · August 1, 2005, 02:15 PM

The bullets could be undersized, did you measure them? The bullets could also be stripping in the barrel, if it was clean when you started shooting what did it look like after? It also could be that your 27 just doesn't like those bullets. I have had really poor results in my revolvers with plated bullets, I have not found a combination that works as well as plain lead bullets and accuracy in general with plated bullets has been quite poor.

Try some plain lead and some jacketed bullets before getting too concerned about it.

rambo1937 · August 1, 2005, 03:34 PM

If I were you I would mic the bullets and the barrel

**Mal H** · August 1, 2005, 10:01 PM

95% of the time keyholing is simply too slow a bullet speed for the firearm's twist rate.

Add more Unique, 6.0 grains is too light a load for a plated 125 gr. bullet.

Quantrill · August 2, 2005, 12:20 PM

Sometimes the forcing cone is leaded up. Check that along with the barrel.

Leftoverdj · August 3, 2005, 01:02 AM

Most likely, the bullets are too soft under that plating. Velocity is not an issue. I have shot god's plenty of 130 cast from a 686, a Security Six, and a Trooper MkII at both higher and lower velocities. Admittedly, I have shot very few plated bullets because the ones I have shot plain did not work for me.

What does work are bullets cast of air cooled wheelweight (c. 11-12 bnh) and sized .359 with any decent lube.

rnovi · August 3, 2005, 01:09 AM

Clean the ever-living snot out of the gun. That won't cost you anything except maybe a few Lead Out patches or some Chore-Boy copper strands. Make sure to clean out the cylinders as well.

Go back out and retest for keyholing.

If it still does keyhole, test a box of factory loads. Do they keyhole? If no, then there is something "odd" about your handloads. If they DO keyhole, slug the barrel and mike it out.

I am betting though you have a severe case of leading somewhere.

**Mal H** · August 3, 2005, 12:45 PM

Quote:

Originally Posted by Leftoverdy

Velocity is not an issue.

Purely out of curiosity, how did you determine that for his revolver? Are the twist rates the same? What is the bullet speed he is getting with that load?

Leftoverdj · August 3, 2005, 01:38 PM

Mal, he told us. It's a pre-27 S&W. Those have perfectly adequate twist rates for any normal .38-.357 bullet. 125 grain bullets are short for caliber and stabilize easier than the heavy bullets. S&Ws will stabilize 200 grain bullets at under 700 fps; They'll sure stabilize a 125 grain bullet at over 1000 fps.

Only things I know of that could be causing keyholing at 7-10 yards are grossly undersized bullets, a completely shot out bore, or severe bullet damage in firing. There are several possible causes of severe bullet damage, of course

**Mal H** · August 3, 2005, 05:20 PM

Thanks - sounds reasonable.

**Unclenick** · August 3, 2005, 08:57 PM

Four more things to check:

Slug the barrel. Take an egg shaped sinker that is slightly over groove diameter or a bullet cast of pure lead and not sized. Wet the barrel and lead slug with oil, and tap the slug into the muzzle using a plastic mallet and a ram made either of a 1/4" brass rod or a 5/16" hardwood dowel rod that is longer than the barrel. Once the bullet enters the muzzle, grasp the ram rod with your hand and slowly push it the rest of the way down the barrel and out the forcing cone with your hand. What you are looking for is feeling any difference in resistance as you go down the tube. If it gets more resistant a half inch or so down the tube, you have a muzzle worn open by excessive cleaning with a rough or jointed steel rod. In that case the barrel needs to be replaced or shortened.

If it gets more resistant as you get to the forcing cone, you either have a huge fouling build-up there (a dangerous condition) or your barrel threads are so tight in the frame that the frame is constricting it. Either way, the bullets get sized down too small on their way through the constriction and accuracy goes all to hell afterward. You cure the problem by lapping the barrel, fire lapping the barrel, or sending it to a reputable S&W 'smith who can pull the barrel and put the threads into spec. This is a common revolver problem, even with Smiths.

The second thing to look for is an off-axis muzzle crown. I've seen this a couple of times on cheap MAC10 knock-offs and the like, but never on a Smith. Nonetheless, check for it.

The third, least common thing to look for is badly cut rifling. I've encountered this twice. Once on a Dan Wesson kit gun a friend of mine owned which shot great with its 2" and 6" barrels, but keyholed badly with its 4" barrel. On examining the muzzle, I noticed the rifling looked deeper on one side of the tube than the other. Slugging then measuring the slug with calipers showed this was the case, with 0.002" deep rifling on one side of the muzzle and 0.006" deep rifling on the other. The bullet was being engraved asymmetrically and exited with its CG off-center and wobbled into the land of lost stability. The second gun I saw like this I didn't get to measure. It was 41 Smith, and .22 rifling is shallow enough that any tiny difference would be bad. I told both owners to get free replacement barrels from their respective factory repair facilities.

Frankly, I don't know how to make rifling that far out of whack? The only thing I can imagine is they were both button rifled and the button tipped. Where else would the deep rifling come from?

Finally, it is also possible for a rough spot to cause fouling to build up asymmetrically and act like off-centered rifling, launching a bullet with its C.G. off center and wobbling into instability. Sometimes fouling can be disguised by carbon. If you have a friend with an Outer's Foul Out, let him run it on your gun first with the lead, then with the copper removing electrolyte. If it is present, this should whack it for sure.

In the old days we just plugged the muzzle with a cork and filled the tube with mercury. In a few hours it amalgamated with the lead and the amalgam could be brushed out easily. Way too dangerous by today's standards.

Nick

impact · August 3, 2005, 10:01 PM

The last time I keyholed paper is when I tried to shoot 69gr bullets in a 222 at 100 yards

. It just did not work.

When you say keyhole are you sure the bullet is going sideways through the paper at 7 to 10 yards? I would think it would be hard to keyhole a target that close! But I could be wrong.

caz223 · August 4, 2005, 07:16 PM

Those soft plated bullets sometimes have a problem with keyholing.
The lead inside is dead soft, and the plating is thin.
The soft lead does not force engagement in the grooves, esp. if the bore is worn, the bullets are too small, or the bullets are going too slow to distort (Obturate.).
If crimped generously, they may mic out fine, but be undersized once loaded.
Do the cases look like they have a good gas seal?

August 1, 2005, 10:50 AM	#1
PinnedAndRecessed Junior member Join Date: November 12, 2004 Posts: 449	Keyholing. I recently bought a pre 27 S&W with a 3.5 inch barrel. I worked up some loads using a 125 grain plated bullet ahead of 6 grains Unique. But at 7-10 yards some of the rounds keyholed. Why?

August 1, 2005, 11:33 AM	#2
Russ5924 Senior Member Join Date: February 18, 2005 Posts: 1,874	I would say better check your barrel for fowling lead or copper.That load should have been OK at that range. You are getting even powder in all cases ?????? __________________ Russ5924

August 1, 2005, 03:34 PM	#4
rambo1937 Member Join Date: June 14, 2005 Posts: 23	key Hole If I were you I would mic the bullets and the barrel

August 3, 2005, 01:09 AM	#8
rnovi Senior Member Join Date: July 10, 2005 Location: So. Cal. Posts: 401	Clean the ever-living snot out of the gun. That won't cost you anything except maybe a few Lead Out patches or some Chore-Boy copper strands. Make sure to clean out the cylinders as well. Go back out and retest for keyholing. If it still does keyhole, test a box of factory loads. Do they keyhole? If no, then there is something "odd" about your handloads. If they DO keyhole, slug the barrel and mike it out. I am betting though you have a severe case of leading somewhere. __________________ Robert N. "Remember, Eagles may soar but Weasels don't get sucked into jet engines!"

August 4, 2005, 07:16 PM	#14
caz223 Senior Member Join Date: May 15, 2002 Location: Michigan Posts: 1,429	Those soft plated bullets sometimes have a problem with keyholing. The lead inside is dead soft, and the plating is thin. The soft lead does not force engagement in the grooves, esp. if the bore is worn, the bullets are too small, or the bullets are going too slow to distort (Obturate.). If crimped generously, they may mic out fine, but be undersized once loaded. Do the cases look like they have a good gas seal? __________________ I'm not just a gun. I'm YOUR gun. (Hold me.)

August 1, 2005, 02:15 PM	#3
HSMITH Senior Member Join Date: June 21, 2002 Posts: 2,019	The bullets could be undersized, did you measure them? The bullets could also be stripping in the barrel, if it was clean when you started shooting what did it look like after? It also could be that your 27 just doesn't like those bullets. I have had really poor results in my revolvers with plated bullets, I have not found a combination that works as well as plain lead bullets and accuracy in general with plated bullets has been quite poor. Try some plain lead and some jacketed bullets before getting too concerned about it.

August 1, 2005, 10:01 PM	#5
Mal H Staff Join Date: March 20, 1999 Location: Somewhere in the woods of Northern Virginia Posts: 16,955	95% of the time keyholing is simply too slow a bullet speed for the firearm's twist rate. Add more Unique, 6.0 grains is too light a load for a plated 125 gr. bullet.

August 2, 2005, 12:20 PM	#6
Quantrill Senior Member Join Date: February 28, 1999 Location: Arizona, USA Posts: 725	Sometimes the forcing cone is leaded up. Check that along with the barrel.

August 3, 2005, 01:02 AM	#7
Leftoverdj Senior Member Join Date: October 15, 2004 Posts: 934	Most likely, the bullets are too soft under that plating. Velocity is not an issue. I have shot god's plenty of 130 cast from a 686, a Security Six, and a Trooper MkII at both higher and lower velocities. Admittedly, I have shot very few plated bullets because the ones I have shot plain did not work for me. What does work are bullets cast of air cooled wheelweight (c. 11-12 bnh) and sized .359 with any decent lube.

August 3, 2005, 01:38 PM	#10
Leftoverdj Senior Member Join Date: October 15, 2004 Posts: 934	Mal, he told us. It's a pre-27 S&W. Those have perfectly adequate twist rates for any normal .38-.357 bullet. 125 grain bullets are short for caliber and stabilize easier than the heavy bullets. S&Ws will stabilize 200 grain bullets at under 700 fps; They'll sure stabilize a 125 grain bullet at over 1000 fps. Only things I know of that could be causing keyholing at 7-10 yards are grossly undersized bullets, a completely shot out bore, or severe bullet damage in firing. There are several possible causes of severe bullet damage, of course

August 3, 2005, 05:20 PM	#11
Mal H Staff Join Date: March 20, 1999 Location: Somewhere in the woods of Northern Virginia Posts: 16,955	Thanks - sounds reasonable.

August 3, 2005, 08:57 PM	#12
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Four more things to check: Slug the barrel. Take an egg shaped sinker that is slightly over groove diameter or a bullet cast of pure lead and not sized. Wet the barrel and lead slug with oil, and tap the slug into the muzzle using a plastic mallet and a ram made either of a 1/4" brass rod or a 5/16" hardwood dowel rod that is longer than the barrel. Once the bullet enters the muzzle, grasp the ram rod with your hand and slowly push it the rest of the way down the barrel and out the forcing cone with your hand. What you are looking for is feeling any difference in resistance as you go down the tube. If it gets more resistant a half inch or so down the tube, you have a muzzle worn open by excessive cleaning with a rough or jointed steel rod. In that case the barrel needs to be replaced or shortened. If it gets more resistant as you get to the forcing cone, you either have a huge fouling build-up there (a dangerous condition) or your barrel threads are so tight in the frame that the frame is constricting it. Either way, the bullets get sized down too small on their way through the constriction and accuracy goes all to hell afterward. You cure the problem by lapping the barrel, fire lapping the barrel, or sending it to a reputable S&W 'smith who can pull the barrel and put the threads into spec. This is a common revolver problem, even with Smiths. The second thing to look for is an off-axis muzzle crown. I've seen this a couple of times on cheap MAC10 knock-offs and the like, but never on a Smith. Nonetheless, check for it. The third, least common thing to look for is badly cut rifling. I've encountered this twice. Once on a Dan Wesson kit gun a friend of mine owned which shot great with its 2" and 6" barrels, but keyholed badly with its 4" barrel. On examining the muzzle, I noticed the rifling looked deeper on one side of the tube than the other. Slugging then measuring the slug with calipers showed this was the case, with 0.002" deep rifling on one side of the muzzle and 0.006" deep rifling on the other. The bullet was being engraved asymmetrically and exited with its CG off-center and wobbled into the land of lost stability. The second gun I saw like this I didn't get to measure. It was 41 Smith, and .22 rifling is shallow enough that any tiny difference would be bad. I told both owners to get free replacement barrels from their respective factory repair facilities. Frankly, I don't know how to make rifling that far out of whack? The only thing I can imagine is they were both button rifled and the button tipped. Where else would the deep rifling come from? Finally, it is also possible for a rough spot to cause fouling to build up asymmetrically and act like off-centered rifling, launching a bullet with its C.G. off center and wobbling into instability. Sometimes fouling can be disguised by carbon. If you have a friend with an Outer's Foul Out, let him run it on your gun first with the lead, then with the copper removing electrolyte. If it is present, this should whack it for sure. In the old days we just plugged the muzzle with a cork and filled the tube with mercury. In a few hours it amalgamated with the lead and the amalgam could be brushed out easily. Way too dangerous by today's standards. Nick

August 3, 2005, 10:01 PM	#13
impact Senior Member Join Date: January 8, 2005 Location: the great state of Texas Posts: 854	The last time I keyholed paper is when I tried to shoot 69gr bullets in a 222 at 100 yards . It just did not work. When you say keyhole are you sure the bullet is going sideways through the paper at 7 to 10 yards? I would think it would be hard to keyhole a target that close! But I could be wrong.