Model 41 Carcano Reloading Help!!

[Patrick Chadwick]

Well I slugged the bore yesterday and it come out right at .267".

Are you quite sure of that? CIP groove/bore dimensions are 6.50 / 6.80 mm = 0.2559" / 0.2677" and it is unusual for a bore to be tighter than the specified dimensions (which is why the 0.267" Hornadys ought to be fine, but 0.264" is on the sloppy side).

How did you slug the bore? By simply driving a well-greased soft lead slug though? - That will produce an undersize measurement.
It is necessary to drive the slug (which must be soft lead) down to the tighest point, i.e. the point where you feel most resistance, and then upset it properly to fill the bore.
This is simply done by using two lengths of 1/4" brass rod.
One is held fast against the slug in the barrel, and the other is driven from the other end against the slug.
The mass of a couple of feet of brass rod is such that you shouldn't need a hammer, just flick the rod smartly down the barrel so that it smacks against the slug to obturate it.
Now push the slug through, and measure it again. The bore diameter may well read a thou or so larger with this method. Measure at the end of the slug that was impacted by the moving rod - that end will have the best obturation.

Of course, maybe your bore needs a hearty decoking beforehand? My 91/41 bore was black when I got it. But sharp and bright underneath the crud!
Rigorous cleaning /copper removal is a prerequisite if you want to use the Hornady 0.267" bullets. Otherwise you will be pressing the crud very hard into the bore and it will be much harder to clean later!


Patrick

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[concretus]

Are you quite sure of that? CIP groove/bore dimensions are 6.50 / 6.80 mm = 0.2559" / 0.2677" and it is unusual for a bore to be tighter than the specified dimensions (which is why the 0.267" Hornadys ought to be fine, but 0.264" is on the sloppy side).

How did you slug the bore? By simply driving a well-greased soft lead slug though? - That will produce an undersize measurement.
It is necessary to drive the slug (which must be soft lead) down to the tighest point, i.e. the point where you feel most resistance, and then upset it properly to fill the bore.
This is simply done by using two lengths of 1/4" brass rod.
One is held fast against the slug in the barrel, and the other is driven from the other end against the slug.
The mass of a couple of feet of brass rod is such that you shouldn't need a hammer, just flick the rod smartly down the barrel so that it smacks against the slug to obturate it.
Now push the slug through, and measure it again. The bore diameter may well read a thou or so larger with this method. Measure at the end of the slug that was impacted by the moving rod - that end will have the best obturation.

Of course, maybe your bore needs a hearty decoking beforehand? My 91/41 bore was black when I got it. But sharp and bright underneath the crud!
Rigorous cleaning /copper removal is a prerequisite if you want to use the Hornady 0.267" bullets. Otherwise you will be pressing the crud very hard into the bore and it will be much harder to clean later!


Patrick

Yes I took a 1/8 oz. lead weight and moved it through the bore. can I use the same slug or should I run another through it?