Can older military weapons be brought out to be used in a major war?

SPC Joel Carter Sr Who you calling old? BWAHAHA!!!

Yes ... and No. What do you mean by "Older"?

If are referring to "older versions", there is a high likelihood you could reuse them without months of overhaul IF the components hadn't change from what's in the logistics system. For example, we have M1 Abrams tanks in storage, but they have a 105mm main gun while the M1A1 and M1A2 use a 120mm main gun.

If you mean systems that haven't been used for a while ... that would almost be like using a system you captured on the battlefield. I'm sure the service members who haven't used it before could figure it out if it's akin to something they use, but sustainment and repair are completely different issues.

So ... theoretically yes and theoretically no. It all depends on which system you are referring to.

Yea, it's possible. But there's other factors to take into account. Is there still bountiful ammunition available? Ability to make said ammunition? Replacement parts available and able to be made? Those are just a few of the things that would be considered.

Depends on the weapon. Some are no longer usable or the system that was used to fire them isn't available. And some require training because few on active duty now understand how to use them.

Interesting question. I can tell you that in war, whatever Soldiers can get their hands on is whatever they will use. That's what history shows us.

Personally, I keep hoping to stumble across an old Davy Crockett and it's recoilless rifle in the back of some motor pool somewhere...

Yes, the Army even keeps track of the tanks are on display in front of VFWs in case we need them back.

Sure. It happens all the time. Depending on context some things like the A-10, 50 cal and B-52 have outlived their expected lifespan by several decades. The BLU-82 daisy cutter was used in Vietnam and recently as the GWOT. Some things just stick around and never completely leave because it is unique and scratches a specific itch. Like the U2. It is one of the weirdest aircraft ever and shouldn't work for a bunch of quirks it has but it is still around since being introduced in 1956. Another example would be the Civilian Marksmanship Program that is used as a release valve for the Government to offload old equipment being removed from the governments inventory. They are still offloading M1's that are still on the books. That means everything that came Post Korean War till now is still somewhere.

really SPC?- look at Korea, Vietnam and everything since- no everybody gets the new toys, so you use what you have on hand! If it killed folks 50 yrs ago, then it probably will still kill them if used properly.

Yes they could, the reality would be why, as we move on no longer training on nor stockpileing old weapons systems.

M14 is still 8in limited use, 45 too. .38 just was completely retired and Ma Deice is over 100 years old. Yes.