slugging a barrel

44marty · Posted: Tue Jun 29, 2010 5:06 pm Post subject: slugging a barrel

I just came across a note at the end of the section for the K-31 in the Sierra reloading manual:

" In developing the following data, we used five different Schmidt-Rubin rifles. Considerable difference in bore diameter caused wide variations in pressure. Therefore, we strongly urge the 7.5x55mm handloaders to slug the rifle's bore and use extreme caution in working up loads."

As a machinist, I have bore mic's to measure both the bore diameter and depth of rifling. There must be some "quick and dirty" tricks for the average shooter to check rifle bores.

Any suggestions?

slimjim · Posted: Tue Jun 29, 2010 6:35 pm Post subject: Re: slugging a barrel

Press or Hammer a bullet into the bore just enough to form it to match the shape then tap it back out. A lead bullet or "slug" would be best. I don't know the details but I have done this with my .45-70. Long range black powder shooters that pour/make their own bullets often do this so they can order molds that closely match their guns.

I could also envision placing a foam ear plug in about an inch, coating the barrel with wax or silicon then using bedding epoxy or substitute. Let it harden and then tap it out with a wooden dowel. Then mic it.

I'm a beginning so other that have done them more might have other suggestions.

Vince · Posted: Tue Jun 29, 2010 11:34 pm Post subject: Re: slugging a barrel

Here you go Marty....supposed to be the "duck's guts" for chamber casting.

CHAMBER CASTING ALLOY

Cheers, Vince

44marty · Posted: Thu Jul 01, 2010 1:01 pm Post subject: Re: slugging a barrel

NICE, Vince

The same company makes Cerrobend - used inside tubing to prevent kinks when bending. We used it in the shop to fill thin-walled plastic parts so that they could be held for machining.

One of the guys cast a teaspoon with the stuff. We then went to a donut shop. When he used his "spoon" to stir the coffee (in front of the waittress), it melted. She was about to scramble around the restaurant and take back everyone's coffee, but we told her what was going on.

Donut Slayer · Posted: Thu Jul 01, 2010 3:56 pm Post subject: Re: slugging a barrel

Vince wrote:

Here you go Marty....supposed to be the "duck's guts" for chamber casting.

CHAMBER CASTING ALLOY

Cheers, Vince

x2 on what Vince posted.

slimjim · Posted: Sun Jul 04, 2010 1:44 pm Post subject: Re: slugging a barrel

This sounds like an amazing metal - really fit for purpose!

gelandangan · Posted: Sun Jul 04, 2010 3:58 pm Post subject: Re: slugging a barrel

I once tried to develop MY own "Chamber casting alloy" using an alloy of bismuth and lead.
I managed to make the alloy to melt at 85C or 185F (thats below the boiling point of water)
Poured it into a nice clean chamber and it WELDED itself there!!!
I forgot to oil the chamber AND forgot about the expansion/shrinkage of the alloy.
Lucky I could just boil the alloy out of the chamber.. made a real mess on the action though

Well, needless to say now I always ensure to oil the chamber well before I cast anything into it.
And that goes with slugging barrels too..

Oil them well using ATF or other high pressure oil before you mess around with the barrel or chamber.