What is causing my keyholing?

[Jayhawkhuntclub]

I've got a new DW Valkyrie (1911) commander. Beautiful gun. But I had a bulllet, maybe two, keyhole on me (out of a couple dozen rounds). No the barrel isn't excessively leaded. I'm shooting Lee 356-124-2R sized at 0.356" with 4.5 gr of Unique at 20 yards. I haven't slugged the bore yet. Think it could be from an undersized boolit? Or not enough velocity?
Something else?

Thanks!

[fast ronnie]

Is this a 9mm or is it a .38? Your post says sized to .356 and that would indicate a 9mm. My .38 is sized about a thou over, .358 - .359. I shoot 158 grain loaded with 4.5 gr unique in a 4 inch barrel.

[Jayhawkhuntclub]

It's a 9mm.

[mdi]

Bullets tumble mostly because they are unstable. Bullet too small for the grove diameter? Undersized bullets too hard? You need to slug the barrel and measure the slug and bullets with a micrometer. Normally lead bullets are .002"+ over groove diameter (I have 3, 9mm with .356", .3575" and 358" groove diameters). This will give you a place to start...

[country gent]

A .356 dia cast bullet may be stripping a little in a 9mm pistol. If your guns chamber allows it try a .358 did sized bullet. My berrata 92 with 356 dia barley holds the paper at 25ft with .358 dia its 10 ring capable. with .356 in it I also get an occasional key hole with lighter loads. With .358 dia and lighter loads the holes are clean and round. I recommend loadin a couple dummy rounds with .358 dia bullets in your cases and doing a "plunk" test to make sure your chamber will accept the extra dia. Also you may want a new slightly larger expander stem to accommodate the larger bullet.

[tazman]

If I remember correctly, the Lee 356-124-2R is a tumble lube boolit. This boolit doesn't have as much drive band area as a convention lube groove boolit. It has a tendency to skid and tumble in many 9mm pistols. Lots of people on this site have mentioned trouble with this particular boolit.
I would suggest trying a different boolit and making sure it is sized appropriately for your barrel.
On another note, some barrels have fairly shallow rifling. These work fine with jacketed bullets but don't grip cast well. If this is the case, about the only thing you can do is use an oversize boolit(as has been mentioned) or use a harder boolit making sure it fits properly.

[CraigOK]

pull a bullet and compare it to one that hasnt been seated. Maybe one of your dies is making your boolit smaller in the process of loading.

[JonB_in_Glencoe]

most keyholing with cast boolits is due to boolit skid.
too small boolit or too soft alloy allow a boolit to skid.

[Jayhawkhuntclub]

Thanks to all! Kind of what I was thinking. I'll slug the barrel this weekend.

[Tom W.]

I've found that both of my 9mm pistols like .358 cast boolits. I makes sizing easier as my S&W .357 likes the same size...

[fredj338]

I shoot 0.357" in all my 9mm because I am not slugging 4-5 guns. I shoot mostly range scrap, air cooled, coated then water dropped.

[gwpercle]

Some 9mm's just don't shoot the Tumble Lube designs well...my theory is not enough bearing surface.
Try going .357 or .358.
I've had much better results with the Lee 356-120-TC and the Lee 356-125-2R , both sized .357 . These are not tumble lube designs but have a conventional lube groove...no tumbling encountered .
Gary

[Paper Puncher]

pull a bullet and compare it to one that hasnt been seated. Maybe one of your dies is making your boolit smaller in the process of loading.

Check your expander stem diam. These are usually sized for Jacketed bullets. Mine left the case small enough that the case was sizing the bullet down no matter what size boollit I started with. When I did what CraigOK said I found the problem. A larger diam stem and the keyholing stopped.

[Yodogsandman]

Size to .358" and you wont have any more keyholing.

[plainsman456]

I have taken to sizing 9mm boolits to 358-359.

They don't seem to get smaller after pulling them from case squeeze.

[GhostHawk]

I had one that did not quit keyholing 3 out of 4 bullets until I went up to .359.

Another was fine with .358.

All my 9's now shoot .38 bullets in the .358 or bigger range.

The trouble comes when you get a gun that wants a big bullet but has too small a chamber to accept it.

I typically run 50% COWW with 50% range scrap, lead pipe or similar soft, then add 1% pewter.

In theory going harder might work, but going bigger seems to always work. So that is the direction I tend to lean in.

Good advice about checking a loaded round, see how bad you are downsizing what you do feed it.

Most of mine are shot unsized until they get so big they don't want to start in the case.

Case in point I recently cast and loaded 300 .45 colt rounds. First 200 rounds I had maybe 6 that just seemed fat. So I just set them aside. Last 100 I ended up sizing 75 back down to .452 to get them to fit in the case right.

Just one of those little mystery's, why only 3 fat bullets per hundred in the first 2 batches but most of the third batch cast big. Mold warmer? Slightly more or less tin? Beats me.

Fit is king, when in doubt go bigger is my story and I'm sticking too it.

[poppy42]

After reading all the posts I have a question. First off I uses both Lee 124 grn RN .356 and a Lee 124grn tc .356 molds I size to .356. Most times the bullet offers very little resistance (if any ) as it is being sized. Basically the same molds as the opp. How would it be possible to size a .356 bullet to .358 or even .357? I get no keyholeing so I’m just curious if I’m missing something. I understand that the op might need a different mold. I would think his load is kinda light. I use unique for both my 9x19 (Luger) and my 9x18 Makarov. My Mak load is 4grns with a 95grn bullet while my 9mm load is 4.9 with the 124 grn bullet. Could not his keyholeing be do to to light a load with a 124 grn bullet? Like I said I am not having any problems. But there is no such thing as to much knowledge.
Thanks for any input.

[GhostHawk]

Only one way I have found to size them bigger.

First you have to squish em or smack em. Rubber mallet might work.

Then you can size them.

I rigged up a system using a drill press to flat point some .308 bullets for a .30-30, and found they got quite a bit bigger. Had to run them through a .314 then a .311 size die. 3 thou big for a .30-30 was no sweat. They shot well. Fill the lube grooves first.

[Moonie]

I size .357 for all my 9mm's, they work well and do not keyhole.

[autopilotmp]

I have the Lee tc mold and had to spin a few bullets in the cavities with lapping compound to bring them up over .3555 and now they cast .3575 just a little out of round but I sIze them to .357. The accuracy out of my wife's RIA 1911 was pretty good but after 50 rounds there were strings of lead down the bore. After sizing to 357 accuracy improved and leading disappeared. Everyone shooting 9mm should forego the 356 molds and go with the 358 molds and size appropriately from there.