[P95Carry]

Re our discussions in this thread re bore slugging ...

http://www.thehighroad.org/showthread.php?s=&postid=215156

Thought I'd post this . something I did some time ago elsewhere, in case it helps. It's very much geared to coping with odd number grooves .. instance 5 in my Enfield ....

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Some while back i wanted to check the bore dia on my .303 .... and as this is a 5 groove ...... had almost assumed it was not going to be possible without a special micrometer.

S&W rifling is also 5 groove if I remember too - certainly my old Model 27 was.

Anyway ... I drew up the barrel cross section and established that if done carefully, it was in fact possible. The drawing is shown below and you'll see that if the mic' is used across the points shown, it will in fact yield an accurate measurement.

As an aside to this .... I have found that, instead of using a large solid lead slug for this job (difficult to extract!!) --- you can actually manage by cutting some discs out of lead sheet (3/8" cutter will do usually for .357 and 5/16" for 30 cal) ... and place each one on top of the other and tap carefully in with a piece of brass, into the muzzle - a coupla inches down.

Then..... using same brass rod or a cleaning rod .. tap them back out. You can also use a slug from a cartridge with a very light powder charge and fire into water, as many know.


http://www.patriotnetwork.net/img_test/303_bbl_slug.gif

[P95Carry]

No interest? ...... :( Maybe this got buried.

[blades67]

Probably just not many folks slugging their Enfields.

[P95Carry]

True about Enfields ........ but five groove also applies to my Smith M27 for example ..... plus, the idea of using a number of precut disks from lead sheet also applies to use in anything .. often easier to get a result compared with a solid slug.

Measurement can be taken from each one of the several disks and establish an accurate figure ... easier in fact to mic up I find than a large slug, sometimes.

[Ross]

Your method simplifies what has been made into a big problem by many. My trapdoor, Snider, Martini, etc. are also odd numbered grooves. Recently on another forum it was suggested that those discs could be rotated after slugging, and measured directly with the size of the anvils on the micrometer bridging the offset. With the groove diameter found, the single depth could be derived and the bore also. It might be necessary to pare a portion of the ridge on the slug to get a true reading.
Finding the actual dimentions of the bore is an interesting exercise and it keeps you from using too small a bullet.
Lately, I just try for the biggest diameter that I can stuff into the gun.
Cheers from Grayest California,
Ross

[P95Carry]

I just try for the biggest diameter that I can stuff into the gun. hehe! As long as that's just cast you're talkin about! http://www.patriotnetwork.net/images/smilies/yikes.gif

[Ross]

P95 Carry,
Yup, mostly lead, but I have on occasion used slightly oversized jacketed bullets, as with an old .223" Hornet Low Wall. It does shoot a little better with the .224's, but then I have no interest in magnumizing it. I have a .225 Highwall for that.
Regards from Grayest California,
Ross