Barrel Porting and Cast

[richhodg66]

Been working on a cheap .357 Plinking load that will use a large quantity of fast burning powder I got for free. Tried it so far in thre revolvers, the forst two shot it pretty well.

I have one that had some considerable work done on it at one time by a previous owner including barrel porting. All the work was professionally done, the timing and trigger pull are perfect, it ought to be a great shooter, but never has shot very well with anything, but to be honest, I haven't shot it much because I lose interest in it and want to shoot others.

Today it shot groups that were three to four times as big as the other two, exact same load under exactly the same conditions. In fact, about a third of the shots key holed.

I'm about to give up on it. I'll probably load up some jacketed loads to try at some point, but I'm not gonna have a revolver that has to use jacketed. It's a six-inch, so I guess there's always the option of having the barrel cut off and making it a 4 5/8".

Thoughts?

[LUCKYDAWG13]

I would clean the barrel real good also clean the ports run some jackets and see how it does I have mag-na-ports on my 454 Encore barrel
and it shoots good what kind of revolver are you shooting

[richhodg66]

This one is a Black Hawk. It's an old one, you have to half cock it to load it, but someone went to considerable expense and trouble to customize it and it should shoot superbly, but my raggedy old Security Six that is shot loose and seems almost worn out shoots circles around it.

[243winxb]

Have/had mag-na-ports on M29 & SBH shooting cast. No problems. Just the red sigh gets black on the M29 and have to clean some lead off around the ports. Accuracy OK, even with the hotter W296 loading . http://i338.photobucket.com/albums/n420/joe1944usa/th_Mag-na-port29.jpg (http://s338.photobucket.com/user/joe1944usa/media/Mag-na-port29.jpg.html) http://i338.photobucket.com/albums/n420/joe1944usa/th_IMG_3306B.jpg (http://s338.photobucket.com/user/joe1944usa/media/IMG_3306B.jpg.html)

[454PB]

I think before I blamed the porting, I'd eliminate other possible causes. Have you slugged the barrel and measured the cylinder throats?

[richhodg66]

No, I haven't. Have owned several Black Hawks over the years, all have been decent shooters. No experience really with porting though. Sure doesn't seem to me like it would be good for accuracy with cast.

Keyholing though, wow. It's the Lee 158 SWC tumble lube version, seems like you couldn't get a more basic .38 bullet than that. I suppose if the cylinder throats were much smaller than the bore size, it might cause that.

[runfiverun]

I'm with 454.
look at the other end first.

[richhodg66]

Just checked with a caliper, inside diameter of all six cylinder throats is .358.

[LUCKYDAWG13]

I'm with 454.
look at the other end first.
+3 this is my 454 with 4 port mg-na-ports at 100 yards with my cast boolits 166958