What to do...I slugged a barrel

[cheese1566]

I slugged my 6" SST Colt KingCobra 357 magnum. I used some soft lead casts from a Lyman 358311 mold. The bullets slugged easily with an oak dowel after tapping in with my nylon faced mini hammer. The entire outer circumferance looks to have touched the inner surfaces so I beleive the bullets were big enough to use for slugging.

The slugs measure .353" give or take. I took several measurments around the bullet to carefully measure the maximum outside dimension and not the grooves left by the rifling.

Does this seem too small? I have a .355 and .358 sizing dies.

[2ndAmendmentNut]

Yes that does seem a little on the small side. You may have problems with excessive pressure. However if you work up your loads keeping an eye out for early warning signs you should by fine with either diameter.

Just as a side thought I recall reading about some revolvers (maybe Dan Wesson) that had a barrel bore that tightened gradually from beginning to end. This supposedly helped with long range accuracy. Not sure if Colt ever tried this in their guns though. Maybe someone else will post about this thought.

[cheese1566]

That's what i thought...shouldn't it probably be bigger then .357-358 (give or take), which is close to the true bore of the rifling? Copper jacket bullets are .357.


This coming weekend I plan on casting some Lee 358-158 RF using pure lead (stick on weights). I'll try reslugging the barrel.

I do plan on using my pure lead supply for light 38 loads in this gun, and then go to my W-W supply.

I have shot about 1000 Remington bulk 148gr HBWC through it with no problems. I have shot 357 magnum full power loads too with no problems-both PMC manufactured and my loads. I have a Chrony and use it in staring new load testing in working up all my loads.

[2ndAmendmentNut]

This might sound dumb, but what was the diameter of the slug you used before you pounded it into the barrel?

[cheese1566]

I didn't measure it. :groner:But I could see the grooves from the rifling and that it was in contact all around it's circumference. The slugs needed some tapping to get started and showed obliteration on the bases to conform to the bore.

I was just researching on the lasc.us website on maybe needing to slug the cylinder bores to find cylinder throat dimensions.

I think I may start over from scratch...

[odoh]

Does it have even number of grooves?

[243winxb]

I think I may start over from scratch...Saw a Colt Python with a .354" groove. It leaded badly with factory soft swaged Hollow base wad cutters on lite bullseye charges. Start over sizing your bore, good idea. Or just size your cast bullets as close to .3575" as you can get and shoot them. Pure lead is Not going to work IMO. 50/50 wheel weight & pure lead might go 900fps with a good lube job. Lyman 358311 mold is listed as dropping a .360" bullet using #2 alloy. So using the 50/50 alloy the diameter should be large enough for sizing.

[Whitespider]

Cheese,
Tight barrels aren't uncommon with Colt revolvers.
I also have a SST King Cobra, 4-inch, early to mid-80's vintage with a barrel that slugs .3534-inch. The cylinder mouths slug at .3593-inch and the chambers are cut on the tight side. It's never been very accurate, but will occasionally produce a promising group.

I shelved the gun several years ago after trying all the mold designs that my boolit-casting friend had. Now that I've got some experience castin' my own and matching them to the several revolvers I own, and because I recently bought a K38 and a few molds for it, I'm gonna pull that Colt out of mothballs and have-at-it again.

[GabbyM]

Measure the cylinder throats and fit the bullets to them.
If it were me I'd size some boolits .358” and .357” then see if they will push through the throats.
I measure them with calibers to check to see if all six are the same. The flats edge on the caliper blades will give a few tenths false reading.

[Guesser]

Back in the early days of handgun sillouette shooting a great many Colt barrels were installed in S&W revolvers because the Colt barrels were tighter and more accurate for the longer ranges but the S&W frames and lock work stood up better to the heavy charges.
I saw one of them at a gun show last year, they were referred to a "Smolts".

[pdawg_shooter]

My Python has a .3575 bore and .3585 / .3590 throats. Guess I just got lucky!

[anachronism]

You could also have a case of thread choke too. Beartooth Bullets has an excellent technical guide that goes into a lot of detail on slugging barrels. One point the make is that you really need to use the egg shaped fishing sinkers with the hole in the center. They want you to stick a nail through the hole, so that you can slug only the muzzle, then pull the slug back out the way it went in. Then slug the full length of the barrel with another slug & compare the two to see if there is a difference between them. This would tell you where to look for a possible bore constriction.

[cheese1566]

I tried the egg shaped and cone shaped ones from WalMart. They are grossly the wrong sizes to fit. I tried the cone shaped in my Beretta 92FS barrel and thought it would go. It got stuck half way through. I seriously thought I would be buying a new barrel after all the pounding on the brass rod (it wedged itself good!!) I then used a small propane torch to carefully heat the area near the lead to soften it enough to pound out-being careful not to get the steel too hot or glow.

I then came across the soft cast bullets.

My locaL WalMart doens't have the sinker variety for sizes- or they are all green freindly zinc.

[243winxb]

just size your cast bullets as close to .3575" as you can get and shoot them

[Char-Gar]

Colt barrels will generaly run .354 - .355 in the grooves. So, .353 is not an off the wall number for a Colt. The largest Colt barrel I have sluged is a 1964 New Frontier than ran .356. Colt cylinder throats generaly run a little larger than Smith and Wesson in the .358 - .359 range. I size my bullets .358 - .359 and get excellent accuracy from my Colts.

Colt uses a 1-15 twist barrel and Smith uses a 1-18+ twist. The Colt handles the heavy weight bullets a tad better than the Smith and Wesson.