I think it’s worth noting that a .001” variation in a .410” barrel is comparatively much less than the same .001” in a 30cal or 8mm for example.
Not ideal but has anyone actually seen a rifle damaged from doing this?
Also common is shooting .358” bullets in 9X57 Mausers Which have a .356” groove. Again, never heard of damage doing this either. In fact, an old gunsmith once told me that they preferred using 9X57 barrels for 35 Whelen builds because the tight bores were more accurate and a bit faster than .358” barrels.
Even today, Ruger used .308” barrels on their 7.62X39 rifles so we all know that .311” bullets have been used in those rifles.
The term(s): "Shot out barrel", "Worn out barrel", "Over bore", "Under bore", "Heavy rifled", all terms used in describing a firearm's bore.
Choose any caliber any any type of rifled firearm.
I'll pick the 404J with a measured .410 diameter bore for an illustration.
Using factory ammo with .410 bullets and upper end of moderate powder charges.
Average range practice 20 rounds with ~2 minutes between shots. On average 8 random range sessions per year, except in prep for a hunt every 2 years and the range time is doubled or tripled with each of these range sessions 40 rounds are fired per session with ~1 minute between shots, and with a ~10 minute break between each 4 shot string.
Several years and 10,000 to 20,000 rounds shot later. The accuracy of the rifle has depleted from super accurate to now looking more like buckshot on the target.
The rifling has been worn down, aka "Shot out".
Switching to a .411 bullet and the rifle becomes accurate again. Another few 100 rounds and the accuracy is lost again. Switching up to a .412 bullet the accuracy returns, BUT the chambering of a round becomes excessively tight/hard/rough, with more noticeable felt recoil, which is due to increase in pressure by the oversized bullet in the barrel throat.
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Even today, Ruger used .308” barrels on their 7.62X39 rifles so we all know that .311” bullets have been used in those rifles.
This can go 2 ways. The short answer is Yes.
The long answer is much more complex and for lack of a better term international politics. Formal foreign policies/agreements/ doctrine amongst foreign nations. Basically seperating what weapons, calibers, types of ammunition/ munitions foreign militaries are Legally authorized/allowed to use and what civilians are can to use, one example: militaries are legally only allowed to use FMJ ammunition, whereas civilians can use both FMJ and expanding ammunition.
Then there are international trade agreements and copyright laws. Whereas countries that ~"lack", the capabilities of advance technologies will simply adapt and alter other countries' technologies for their own use.
Here are just 3 examples:
308/7.62 × 51 NATO vs 7.62 x 39 and 7.62 x 54R
308 NATO firearms won't chamber either of the Russian calibers, yet the Russian 7.62 x 54 can chamber and fire 308 NATO ammunition.
At the time/Back then, Russia and China being "~not so friendly" towards each other and being "neighbors", China obliged themselves by stealing Russian designed weapons and ammunition to manufacture these weapons and ammunition for its military.
The Japanese on the other hand, out of desperation, developed the 7.7 x 58 cartridge for use by their military. They simply modified 30-06 NATO brass and topped it with a 303 British bullet.
