Ruger American 308 Impact Chamber Slug

[thegreatdane]

Guys, I recently slugged (both traditionally and chamber/throat impact slugged) my Ruger American 308. See the picture below:



It measures:
Throat 0.311
Groove 0.309
Land 0.305

This seems .001 large for a .308. Is this common (.309)? That said, from research, I should size for .311 correct? I have several molds on the way and have yet to buy my sizers. I've measured both numerous times with multiple calipers from all different angles, because I didn't like the results...

Good folks of castboolits, please advise.

[tomme boy]

Size it 0.311" and see if it chambers. Neck may be a little tight.

[tomme boy]

Measure the out side of some fired cases and see what that is. Measure a case that has the 0.311" boolits seated in it. Should tell you if it will chamber or not.

[Lefty SRH]

I think Tomme Boy hit it on the nose.

I slugged the barrel of my Ruger Gun Site Scout and the groove measure .308 exactly! I have tried doing an impact slug but I couldn't get any results. Can you post a "How to" on making an impact slug please.

[thegreatdane]

I think Tomme Boy hit it on the nose.

I slugged the barrel of my Ruger Gun Site Scout and the groove measure .308 exactly! I have tried doing an impact slug but I couldn't get any results. Can you post a "How to" on making an impact slug please.

Thank you, guys. I'll take all of your advice into my planning.

How to create a chamber cast via impact slug:

1) fill a fired case with lead, up to the neck, but short of topped-off. Close the bolt.
2) insert a quantity of soft, preferably pure lead into the muzzle. Use enough to fill the case void, throat, and beginning of rifling.
3) using a strong rod of similar bore diameter, pound the soft lead into shape. You'll know it's filled when the rod bounces back and feels "firm." It's a good idea to wrap a steel rod with electric tape to prevent damage. It's also a good idea to pull the rod back periodically when pounding. Otherwise it will sink into the soft lead and could become stuck.
4) Unlock the bolt and gently tap your creation out, paying special attention to prevent damage.
5) Take measurements. Note: since we've used soft lead, you must measure very carefully. Calipers will scratch and deform.

[Lefty SRH]

Thanks, thats what kept happening to mine. I used brass rods and they kept sinking into the soft lead I was using.

[Lefty SRH]

I wonder if a wheel weight boolit of same diameter would work (keep from sinking) between the soft lead and the rod.

[Wayne Smith]

Loose the calipers. Get a micrometer. You will have accuracy to three or four places, now you have accuracy to two.

[swheeler]

Loose the calipers. Get a micrometer. You will have accuracy to three or four places, now you have accuracy to two.

+1. groove.309/bore.305? rifling sounds pretty shallow to me, .002 deep

[thegreatdane]

I will. Soon as I find one local, i guess.

Sent from my SCH-I535 using Tapatalk 2

[thegreatdane]

UPDATE: I bought a micrometer. Boy, am I glad I did.

I must correct my previous measurements:
Throat 0.3114
Groove 0.3088
Land 0.3020

I will be sizing .310.

[thegreatdane]

Also measuring the lands is quite difficult. So take that particular measurement with a grain of salt.

[swheeler]

Also measuring the lands is quite difficult. So take that particular measurement with a grain of salt.

A set of pin gages works wonderfully for this and cylinder throats. I do think your .310 sizing is appropiate though.

[HARRYMPOPE]

Chamber as big as diameter bullet that it takes without forcing the bolt handle down.I have never slugged a bore or throat and had success with this method.Then if it doesn't shoot start sizing them down .001 smaller at a time.

George