Slugging a 5-groove Enfield

[DanM]

I just got my first Enfield, a clean No4Mk2, all matching, with a like new bore. Well I slugged the bore, but am having a hard time measuring the slug, since the grooves are not opposite each other. What is the trick?

[twotoescharlie]

wrap a thin feeler guage around slug, mike, subtract the thickness of the feeler guage X 2

TTC

[DanM]

OK. I did the measuring, and the math, and it came out to .311. Tighter than I expected. Will re-slug and try again. The bore on this Enfield does look new, maybe I got lucky on this one!

[The Double D]

Take the slug and roll it between the slack jaws of your dial caliper. Do it several times. You will see a number that repeats.

[Buckshot]

.............Measure the barrel OD right at the muzzle. Then pinch the wall of the barrel in a groove, between the jaws of your calipers. Subtract 2X barrel wall measurement from the bbl OD.

.............Buckshot

[vernz]

One method that works with a good degree of precision is to:

Place bullet slug with odd number of grooves in a V block with "grooves" resting on the block.

Set a firmly mounted dial indicator on the top "groove" in the V block. Rotate the indicator dial to zero wherever the needle is.

Pull out the bullet being measured and place cylinders with known diameters in the V block until one is found that also zeros the indicator needle. Drill bit shanks work well for this or cylinders with the range of diameters needed can be turned on a lathe.

Measure the equivalent diameter cylinder with a micrometer and you have your groove diameter.

I would welcome any comments on this method which was shared with me by my machinist shooting partner.

Vern

[JeffinNZ]

Slug the throat of the chamber and establish that diameter and forget the groove.

Just a thought.

[Larry Gibson]

Slug the throat of the chamber and establish that diameter and forget the groove.

Just a thought.

That get's my vote.

Larry Gibson

[felix]

Yep, shoot the biggest boolit that will chamber with 0.001 clearance all around the case neck. Find and use the case with the fattest neck thickness from the cases to be used in that gun. Use a sample of 30 cases if you find a lot of case neck variation between those you measure. 30 is a magic statistical number. ... felix

[Pepe Ray]

Vernz' me'lad, If you've got that much machine shop resources then you're creating much more work and frustration than necessary.
The process has been discribed in detail in a thread (sticky?)If you can manufacture a V block of a specific angle then all you need to do is a direct msmnt and use the formular to give the correct diameter. 1,2,3, presto!!
I can understand why someone would dub around with wrapping a feeler gage around a slug or fumbling with rotating a slug in michs when the have no other resources, but for someone to have a machine shop and machinest available and not avail themselves of the proper tool is sillyness.
Sorry, I ran out of sympathy this PM.
Pepe Ray

[DanM]

The only possible mold I have right now is a Lee 311185/1R. It drops boolits only around
.3125". I have my fingers crossed on this one, hoping the new bore of this Enfield is tight enough to work with these boolits. Will do a chamber cast if they don't work. May try them unsized. Have already opened up a .311 sizer to .312 for the Mosin. Will tweak it to .3125" if needed.

[vernz]

pepe ray - although my friend is a machinist he works for a major corporation and really cannot do custom work for his friends. That is unless he wants to take a run at getting fired. I used the method I described with a 45 degree V block that I happen to have and it worked for me. Can you direct me to a source of information using V blocks for direct measurement?

Vern

[Pepe Ray]

The original printed article was in an American Rifleman many yrs ago. That was reprinted in the Harrison's (NRA) cast bullet Publication, circa 1979.
In response to this question (Many), I posted a synopses in Nov, '06. in the Special Projects Forum. It doesn't appear to be there any more. I can find it by searching my posts (Page 9). I'm not clever enough to know if you can do the same thing. Try it.
For a correct measurement a 108* angle is needed. And the formula. It's all there.
Pepe Ray

[floodgate]

O. H. McKagen, Falls Church, VA has such a setup and provides free (with SASE) odd-groove bullet measurements as a service to the shooting community. He is a regular in the single-shot, black powder and cast bullet magazines and had an article on his tools and methods a few months back; unfortunately, I can't locate his address just now, and my latest "Fouling Shot" (which had a note from him) went to a friend a few days back. But someone here (Dale 53???) must have that info handy.

floodgate

[Buckshot]

The original printed article was in an American Rifleman many yrs ago. That was reprinted in the Harrison's (NRA) cast bullet Publication, circa 1979.
In response to this question (Many), I posted a synopses in Nov, '06. in the Special Projects Forum. It doesn't appear to be there any more. I can find it by searching my posts (Page 9). I'm not clever enough to know if you can do the same thing. Try it.
For a correct measurement a 108* angle is needed. And the formula. It's all there.
Pepe Ray

............Pepe Ray, it's still there. On any particular forum entry page, go to the bottom and there is a menu for "Display Options". You can set that for the length of time you want to display threads. Set it for 'Forever' or 'Beginning' and you'll get every thread ever started since day one.

............vernz, that's an elegantly simple way to getterdone. Assuming you have the tools.

.............Buckshot