Reloading the Carcano

[Andy]

Many who reload the Carcano use the Hornady "0.268"" bullet (in fact it measures 0.267"), and are aware of the strange loading requirements prescribed by Hornady for their use, e.g. magnum primers and specific powders and charges. This is the first time anyone has explained why, and it's good enough for me. Take varying groove sizes, deep rifling and gain twist and you can get a very special situation. It appears that using 0.264" bullets, while not necessarily accurate, is safe, and requires no special loading restrictions. The same would go for cast bullets, except that they could be sized appropriately, and would be accurate (at least they are for me).

Thanks to "mag" from Gunboards. With so much rumour, hearsay and just plain nonsense, it's nice to see some real research and informed conclusions.

06-20-2008, 08:51 PM
mag
Senior Member


A friend and I have shot 1000's of the "big" Hornady .267 dia 160 rn bullets, A lot of testing in over 50 different carcano rifles and carbines of all models. We did this as soon as the bullets came out. Both of us have found that there is a problem with this bullet . Here is what we have found, and why it is a problem . We did find that sometimes you could get 30 or 40 rounds fired with no problem before something bad happened. Since we were firing over 100 rounds per day at times, it was much more likely for us to see it compared to a guy that only fires 20 rounds every month or so. The designer of the bullet did not seem to understand some things about the way most European military bores [ and Carcanos ]were made to shoot. They did not use groove size bullets for a reason . The Carcano has very deep rifling and this is the cause of some of the problem. Also the Carcano's bore size [ land and groove ] did change over the years. The early rifles had a larger groove [ about .272 ] and the groove size did get smaller to about .266 [ with shallower rifling ]with the M-41's . So any pressure data produced from one size bore with not be the same as what was made from another. The land size is what is causing the Hornady bullet to have problems. We have found that the rifles with the smaller lands are more likely to have problems with the bullet, and that it can be a size differance as small as .001 [ .002 total of both sides ] . The deep rifling of the Carcano was cutting through the jacket on the original "big" bullet. To fix this the jacket was made thicker , this caused another problem, that was made worse by the gain twist rifling. It was very hard for the rifling to engrave the thick jacket so deep into the bullet [ this slows the bullet down and causes pressures to go up. Then when the bullet has to "re-engrave" when the twist changes the perssure goes up some more. The " recomended" powders did help with this on some of the less tight bore [ their test rifles ? ] , but it still did not fix the problem on real tight bores [ that they did not have to test ? , but other's could be shooting ] . There was a reason the Italians made their bullets .265 to .266 and used the material that they did for the bullet jacket . The long undersized bullet [ open at the base ] would still ride straight down the bore, the base would seal, and the "extra" bullet material that was displaced by the deep rifling would have the extra groove depth to go into,, and there was also room for the rifling cut "wings" to shift to as the twist changed . To see why this is a problem all you have to do is figure the bore area of a .253 land - .268 groove barrel and compare it to the area of a .267 dia bullet. Where is all that extra displaced bullet material going to go ? It is not going to displace exactly the same each shot. That is why pressures can spike .
I have seen the big bullet [ shot with the recomended load ] have the jacket get stuck in the bore ,way into the gain twist, as the lead core exited. This could also be another cause of over pressure if a shooter fired another round into the stuck jacket. Between the two of us we have had many case faliures with this bullet. We will not use it in Carcanos any more. So the bottom line is they made a bullet that will only work in some of the rifles, needs the load to be matched to each rifle, is not for non-expert reloaders [ or "custom reloaders" that have no idea what size bore rifle their ammo will be used in ] and has a very narrow reloading spec . I knew the bullet would be pulled from the market after a while from the problems I knew it was going to cause. So I bought several 1000 extra right after we did our testing. The bullet does work well and shoot well in some OTHER types of " 6.5mm " rifles, many times it is the only one that will . This is what I have found, some may find it interesting . I do feel the big bullet will get you [ in many of the rifles ] if you shoot it enough. I had a M-91 lr that was shooting it pretty well, over 80 rounds in testing with no problems at all and good accuracy . I shot the rifle in a match and the 14 shot blew the case apart. So number 94 shot in THAT rifle got me. mag

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