Range Report - 1891 Carcano (1896)

Attachment 34126Got up at six am and headed to the range after coffee and loading the truck. Set up a target and settled in at the 25 yd sighting line. Aimed at the lower edge of the target and buried the front sight in the V of the rear sight. Bang! Hog Eye, as me shooting partner likes to say when the X-ring is hit. OK, yesterday after much research and discussion, I loaded three different combinations for the Carcano:
140 gr Nosler Partition with 27.3 gr IMR 4064
160 gr Hornady .268 Round Nose with 27.3 gr IMR 4064
160 gr Hornady .264 Round Nose with 27.3 gr IMR 4064

Fired a shielded test shot into the backstop while hiding behind some 2x6s just to be safe. Nothing exciting happened. Fired the first shot as described above, then two more of the 140s. (see photo) Not a bad three shot grouping for an old girl with questionable handloads - two Xs and a 10.

Next, I tried on of the Hornady 160 gr .268. Again fired behind 2x6s. It went bang, but when I went to extract the case, the bolt was locked closed. After some banging on the bolt handle, the bolt turned, but left the case in the chamber. I used a cleaning rod o remove the case. On inspection, the bolt face had made an impression on the case and the primer was cratered. I didn't fire anymore of the .268s.

Next I tried the Hornady 160 ge .264s. Fired one sighter - the hole on the edge of the 10 ring in the photo. I decided to hold off until I can get a taller front sight installed.

I think this is going to be a keeper.Attachment 34126

Somewhere out there is a definitive article by David Emery on Carcano reloading. If you use the .268" bullet from Hornady, the load and type of powder are to be very critical. Basically, it is a balancing act to get just enough thrust to prevent the bullet plugging the bore without generating excessive pressure.

Some observations of my own:
I measured 10 of the Hornady .268" bullets. Using a Moore & Wright bench micrometer that has 0.0001" divisions on a 2" drum and a fiducial indicator. Not funny electronics, just high-quality mechanical engineering. The diameters, measured 1 cal. from the base, were ALL in the range 0.2671" to 0.2672", the average being 0.26715".
10 Norma Carcano bullets ranged from 0.2639" to 0.2643", the average being 0.26412"
And finally, 10 original Carcano bullets (postwar production) ranged from 0.2662" to 0.2669", the average being 0.26647".

So the average diameter of the Hornadys was only about 0.0007" larger than the average original Carcano bullet.
And in my M91/41 they perform without any problems.
HOWEVER, if you are shooting the M91 long rifle, the internal ballistics are complicated by the gain twist. If you imagine a bullet with the rifling engraved on it, then as the twist becomes sharper the engraving itself is forcibly twisted, which means considerable shear forces on the jacket. In this situation, even a slight variation in diameter is going to produce substantial variations in the shear force. It is easy to imagine that this shear tends to make the jacket lose its bond with the core, which would result in either the buller disintegrating or a catastrophic loss of accuracy if it managed to stay in one piece.

I measured the bullet diameters one caliber from the base. There is a good reason for this. I observed that the older Carcano bullets had an open base (no jacket covering) , and the diameter right on the base was a tiny bit larger. This may be more accident than design, but it has the effect that the base can obturate a tiny bit when the bullet is fired, thus achieving a better fit to the rifling with the original bullets than one would expect from the diameter of an unfired bullet. In effect, a tiny driving band is generated at the base.

Conclusions:
The original Carcano bullet is about 0.002" larger in diameter than a modern 0.264" bullet.
The flat base probably assisted the internal ballistics by bumping up a fraction of a thou when fired.
A modern 0.264", especially a boat-tail, is thus not the ideal projectile.
The (nominal) 0.268" Hornady bullet is the wrong answer to the problem, especially in rifles with a gain twist, as the driving force (and hence the pressure) required to force the bullet into the lands and further distort it as the twist progresses is considerably increased by the oversize cylindrical section.
So flat based bullets will perform better than boat tails.
Open flat-base bullets (no jacket) will perform better still.

All, of course, my own opinions. Comments welcomed.

:wave:
Patrick

Patrick,
Thank you for a very detailed explanation of the various forces and factors that must be considered when reloading for the early 1891 Carcanos. You descriptions and conclusions make sense to me. I need to try a fat based bullet, although the boat-tailed one did reasonably well. Thanks again. --RBS

One of Hornady's early data sheets on the .268" bullet. Note the caution against reduced loads.

https://www.milsurps.com/images/impo...2/r9ef5c-1.jpg

Thanks Parashooter!
That is precisely the handwritten data sheet I referred to earlier, without being able to find it myself. If I remember correctly, this data sheet was composed by David Emary (or is it Emery?) for Hornady, and what bothers me is that, as far as I am aware, this data never made it into a printed recommendation from Hornady itself.

Note the narrow ranges of the powder weights - the balancing act between providing enough thrust to ensure that the oversize bullet is forced through the rifling and does not just plug the barrel, and providing so much thrust that direct overpressure from the powder burn causes a hazard.

I find the old Carcano bullets with the slight rim on the open base that (presumably) upsets to form a small driving band to be ballistically more convincing - and less hazardous!

:wave:
Patrick

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Originally Posted by Patrick Chadwick

I find the old Carcano bullets with the slight rim on the open base that (presumably) upsets to form a small driving band to be ballistically more convincing - and less hazardous!

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Winchester must have thought so, too, as the bullet made for the .264 Winchester Magnum was designed as a dual diameter projectile. Bore riding dia. up front with a groove diameter section at the rear. Good luck finding any "loose", though.

The data table above is what is more or less ended up in the Hornady manual. But, like you, I have noted that the bullets currently sold are NOT 0.2676" Diameter. Significant? Dunno. Hornady seems to have used both 0.268" and 0.267" when referring to the Carcano projectile.

But the maximum military bullet dia. of 0.2669" is so close to the current Hornady size (0.2672"), it seems that some other factor in the bullet's construction would be to blame for a run up in pressures.

As described by Emary in an article apparently no longer available on the web (formerly at http://personal.stevens.edu/~gliberat/carcano/emary.html ), the mechanism behind the pressure anomalies is that the bullet has to be driven into the lands with sufficient force to engrave without hesitation. Reduced charges that fail this requirement allow the bullet to hesitate upon reaching the end of the long Carcano throat, producing a hazardous pressure spike.

Durn. I printed that page by Emary some time ago, then forgot about it. I was using the Hornady load data from my set of books which lists the 27.3 gr of IMR 4064 as the starting load.

Guys, please note: that table was set up for a Fucile 91/41 - the shorter rifles (NOT carbine) with new barrels that had a normal twist, NOT a gain twist.

The situation in a barrel with a gain twist is going to be somewhat trickier - because of the huge force required to screw the engraving round as the twist sharpens. I would not wish to try an oversize bullet in a gain-twist barrel!

Patrick

Just where exactly does it say this data is not to be used in gain twist barrels? Why produce data that is only safe to use in just one of a dozen or so firearm variants chambered for the same cartridge then neglect to include this information in the hand written warnings at the bottom of the sheet? To date I've put 200 or so rounds loaded using this data through an M1938 short rifle w/gain twist and without a single issue of any kind.

I've shot them as well in gain twist barrels. No dramas. I don't think gain twist is the issue.

If I remember Emary's article accurately, he tested loads in gain-twist barrels as well as the constant-twist M41 referenced on the data sheet. From an engineering perspective, the force required to enlarge the engraved area as a bullet progresses down a gain-twist barrel is a minor factor considering how little additional metal must be displaced and how much momentum the bullet has acquired before the twist sharpens significantly.

The pressure anomalies with reduced loads apparently occur as the bullet reaches the end of the fairly long freebore in the Carcano throat. When there is sufficient pressure and momentum at this point to fully engrave the bullet, regardless of twist pattern, the pressure curve is normal.

Since my Model 1891 made in 1896 has the gain twist rifling, I guess I'll stick with the .264 bullets - anyone need some .268s?

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Originally Posted by vintage hunter

Just where exactly does it say this data is not to be used in gain twist barrels?

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Wrong perspective! It says explicitly that it was for the M41. It does not have to say what it is not for. You are making an assumption if you presume that it can be used for other models. The author of the data sheet bears no responsibility for this assumption. Please read the disclaimer printed at the top right of the sheet. It is there as a warning. If it works for you, fine, if not, the author is not responsible. "Gain twist barrels" would include the 6.5 conversion of the 1870 Vetterli, known to the Italians as "Il Terribile". Would you want to feed one of those with modern loads?
:wave:
Patrick

P.S. On Saturday I test-fired an old revolver for which I had no satisfactory load data. Reading around and comparing what meagre information was available, I started with a load that was so soft that the bullet stuck in the bore. But not in the forcing cone, as one might expect. It stuck in the muzzle, peeping out a millimeter or so! I wish I had had a camera, but there were several amused witnesses. At least I now know that this revolver does not have a wide muzzle. And heavier loads (I had, of course, prepared a series) performed well.

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Originally Posted by Parashooter

If I remember Emary's article accurately, he tested loads in gain-twist barrels as well as the constant-twist M41 referenced on the data sheet.

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I do not wish to tread on anyone's toes, and you may well be right with regard to the forces, but the article by David Emary only gives load info for an M91/41 in 6.5mm (constant twist) and an M38 cavalry model in 7.35mm (also constant twist). I can find no mention of loads for any gain-twist models, and a definite warning against trying the .268" bullets in the Vetterli conversion. The article is lengthy and includes info from other sources, but as far as I can tell (and it's late here, so I may have missed something), the only types tested by David Emary were the M91/41 and the M38.

:wave:
Patrick

No Patrick it does not explictly say it is for the M41 only, it simply states the M41 just happened to be the rifle chosen for final testing. IF this data was intended soley for use in just one model it should and most certainly would say so in bold print. Imagine, in this lawsuit happy world, the liabilities a company would face by not making such knowledge known to the end users. As for the disclaimer, it's found in all loading munuals I've ever seen, pretty much word for word. To hopefully solve any doubts about the subject I phoned Hornady(800-338-3220) and asked whether or not this data and .268'' bullets would be safe to use in gain twist barrels. The technician I spoke with(Brad) said there would be no problems with using this bullet/data combination in ANY CARCANO(Vetterli's are not Carcano's) w/gain twist barrels providing the rifle is in good condition and the exact components shown were used with exception to the brass where PRVI cases could safely be substituted for the Norma's. What about all other load data? Theres only one rifle shown as the test platform, does that mean 8x57 data developed in a K98k is unsafe for use in any other variant of M98 Mauser or in modern sporting rifles of the same caliber?

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Originally Posted by vintage hunter

with exception to the brass where PRVI cases could safely be substituted for the Norma's.

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IIRC, the Prvi cases are what's listed in the published data.

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Originally Posted by vintage hunter

No Patrick it does not explictly say it is for the M41 only,

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Please read what I wrote.

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Originally Posted by Patrick Chadwick

It says explicitly that it was for the M41.

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I did not write "...for the M41 only".
You are making an assumption again. That is one reason for a manufacturer or author to include a disclaimer in such a text. M41 is what it says on the handwritten data sheet. Not "M41 only". Not "Carcano rifles". Not "gain twist barrels". Just M41. And in the article by David Emary it says "M91/41", which is the designation as used by the Italians for the same rifle.

Aren't Carcanos fun? Very Italian. Always a spirited discussion.

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Originally Posted by vintage hunter

As for the disclaimer, it's found in all loading munuals I've ever seen, pretty much word for word.

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Because people tend to read into such sheets what they expect, not what is actually presented. As soon as the reader starts to interpret or make assumptions, he is venturing into territory that is excluded by the disclaimer.

I am not claiming that the (nominal) .268" bullets and the loads published in the handwritten data sheet (which does not appear to bear the name of David Emary) or the lengthy article which does bear his name will be dangerous, hazardous, fun, or the most accurate load ever derived. I am not making any claim about the applicability of the load at all.

As for

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Originally Posted by vintage hunter

The technician I spoke with(Brad)

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in

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Originally Posted by vintage hunter

this lawsuit happy world,

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if you had trouble with that load in any other Carcano, I suspect you would hear something on the lines of
"Reloading is always on the responsibility and risk of the user..."
"You must have misunderstood him..."
"Brad had no authority to make such a statement..."
"Brad who?"

Perhaps y'all ought to get the reloading manual and read the entire introductory paragraphs. Hornady is pretty good about making disclaimers. Read the 8mm Mauser caliber entry for one example.

O come off it Patrick, you're making more assumptions than you're claiming I am. It's plain to see neither of us is gonna roll over and play dead so I suggest we let this P!%%ing contest between us drop before it gets personal. You believe what you want to based on the information you have and I'll do the same. Now are we friends again or what??

Jm, I have done just that many times and without even looking( don't really know exactly where my Hornady manual is ATM) I know just what your referring to, ''do not use this data for the modle 1888'', or words to that effect. Right?

Well, amongst other warnings for the 8mm, yes, or something to that effect. Manual's at the house, where there's no computer.

Other examples- Hornady has probably three different tables for 45-70 with different applications in mind. They have warnings about the non-interchangibilty of the .222 Rem Mag and the .223 Rem. All sorts of things that would indicate that if there was more to consider when loading for the Carcano, they would have included it. It's not like there aren't all sorts of dire warnings in that section already.

BTW, it's not like Hornady hasn't been loading ammo and selling it commercially themselves. Which ammo could end up in any old Carcano. I've shot it. It's not downloaded.

In fact, I would recommend most folk shoot the factory stuff first. Another layer of protection, if you will. And it's not all that expensive when it's available.

I do have a Carcano carbine getting sorted. But what with blackberry season on and overtime and setting up the new shop, I don't know when I'll shoot at the range!

Also have a 7,35 short rifle to shoot that's been patiently awaiting a go.

Oh how I wish there was such a thing as 0.266" jacketed bullets! One can get them as hard-lead cast bullets, but up to now I have had no success with them.

When I get around to it - my present excuse is that I have 2 competitions with the M1917 in the next two weeks, so let's say July sometime - I'm going to take a few 264s and turn off the base of the jacket in the lathe, to see if this produces any improvement by (so my theory) allowing a touch of obturation of the base.

:wave:
Patrick

Watch that you don't blow the core out of the bullet! That could be a REAL drama.

I'd considered doing something similar with Nosler Partitions, forming a concave in the base sorta like a Minie Bullet.


BTW, does anyane know how the gain twist in a Carcano barrel starts out and ends up? Don't know how reliable the info I have is but it lists it as starting out at a rate of 1:19.25 at the breech end and finishing up at 1:8.25 an the muzzle and the rifling makes the same transition regardless of barrel lenght.

Whew! I'm worn out from reading this thread, and I have forgotten who's on first.

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Originally Posted by RBruce

Whew! I'm worn out from reading this thread, and I have forgotten who's on first.

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That would be you! It's your thread on which we're running amuck.

BTW, I found a tatty old '91 TS with a less than stellar bore today. Even though it looks quite spiffy at 30 feet, I think it might be a good test vehicle for the Hornady bullets.- Gain twist rifling and tiny pits from start to finish. Muzzle's washed out, though so accuracy probably won't be ggod.

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Originally Posted by vintage hunter

BTW, does anyane know how the gain twist in a Carcano barrel starts out and ends up? Don't know how reliable the info I have is but it lists it as starting out at a rate of 1:19.25 at the breech end and finishing up at 1:8.25 an the muzzle and the rifling makes the same transition regardless of barrel lenght.

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For the M91: Starts at 578 mm (22.75") with a pitchangle of 2.02 degrees. Tightens linearly (i.e. there is no sudden tightening) to 201 mm (7.9", 5.8 degrees) at the muzzle, over a barrel length of 781 mm.
For the Moschetto M91: Starts with 389 mm (15.3", 3.00 degrees) and tightens to 190 mm (7.5", 6.12 degrees), over a rifling length of only 375 mm.

As you can see, the twist progression is NOT the same for all models, and on the Moschetto it is a fairly ferocious tightening, which is why it is not unreasonable to be worried about the jackets on oversized bullets being twisted right off the core.

:wave:
Patrick

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Originally Posted by Patrick Chadwick

As you can see, the twist progression is NOT the same for all models

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How about the '91 carbine and the '91 TS? Those are the "shorties" I have. The carbine has been no dramas, if not very accurate. The "new" crapola TS was obtained partly just for these experiments.

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Originally Posted by jmoore

How about the '91 carbine ...?

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The Moschetto M91 is the carbine version of the M91 long rifle. Originally intended for the cavalry, it was designated Moschetto M91 d.c. ("da cavalleria")
after the introduction of the Moschetto M91 TS ("Truppe Speciali")

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Originally Posted by jmoore

...and the '91 TS?

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This uses the same barrel as the Moschetto M91 d.c.

And before anyone asks...

The Moschetto M91/24. The "pocket rifle". This is probably the nearest thing to those jokey "tanker" rifles fudged up from old Lee Enfields that was ever produced by a regular arsenal. The first version simply had the M91 rifle barrel cut down to a rifling length of 377 mm. Which meant that the faster twist end had been cut off, and it was a ballistic flop.

For the second version, someone applied a bit of thought before starting up the saw, and these had an M91 rifle barrel shortened at the breach end, and then an insert/sleeve made to attach this to a new breach. So the twist has to be worked out backwards from the muzzle, giving a twist at the muzzle of 201 mm (as already given for the Fucile M91) and 360 mm (3.25 degrees) at the start of the rifling, a little sharper than the Moschetto M91.

After all this, the Italian arsenal engineers must have been heartily sick of the whole gain twist business, and it is not surprising that the 7.35mm carbines and the Fucile M91/41 were designed with normal constant twist barrels.

:wave:
Patrick

P.S. If there are any mistakes in the above values, it is probably because I am getting confused as well!

Yah, stupid of me!

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Originally Posted by Patrick Chadwick

Moschetto

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Somehow in my haste I had in my pea brain yet another even shorter variant, but all of the carbines are Moschetto models. (What's the plural of Moschetto?) My only "book" dedicated to Carcanos is a first (only?) edition Hobbs, and it's little more than high school term paper with drawings and one low resolution photocopy photo stuck in loosely. Still useful and was never intended to be an "end all, be all" reference!

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Originally Posted by jmoore

What's the plural of Moschetto?

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Moschetti

I remember seeing stories about sporterizing Carcanos. Guys would shorten the barrel and discovered they were very inaccurate rifles. The concept of gain twist was largely unknown.