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

[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?

[Patrick Chadwick]

Take a fresh slug. Check your measuring device (micrometer, slide gauge). Just wiping over the faces of the jaws can make a difference to the zero. Rember, just beacue you can read it to a thou, that does not mean it is accurate to a thou.

Patrick

[concretus]

I loaded a few rounds @ 34.0 gr of H-414 w WLRM primers and the .268 dia. 160gr Hornady bullets. Followed the Hornady sheet. It still blew out the primer. Then I tried the 160gr Hornady RN at .264 dia.. Started at 34.0gr (as recommended), 35,0 and 36.0. The 34gr load blew gas back do failure of the case to expand and seal in the chamber. The 35.0 gr load fired off but the primers were raised after inspecting the case. The 36.0 gr load actually fired good with a 3"-4" group and the cases looked fine. No flattened or blown primers. Text book of what happens w/ low charges slow burning/ magnum type primers. It's a start and seems promising.
I have a question; Since the rifle is somewhat shooting decent w/ .264 dia bullets, would the 160gr RN bullets be preferred due to the added surface area, or could I try the 140gr bullets? Also, with the smaller dia bullet; can I use a regular large rifle primer w/ the other type powders; (IMR4064, Varget, H4895, IMR 4350, etc)?

[Parashooter]

I have a question; Since the rifle is somewhat shooting decent w/ .264 dia bullets, would the 160gr RN bullets be preferred due to the added surface area, or could I try the 140gr bullets? Also, with the smaller dia bullet; can I use a regular large rifle primer w/ the other type powders; (IMR4064, Varget, H4895, IMR 4350, etc)?

The answer to all three questions is yes.

Be sure to read and understand Dave Emary's comments at SHOOTING THE 6 before experimenting further with the .268" Hornady bullets. Although his experience with H414 differs from yours, the underlying phenomena described may give some insight into your problems.