what do u think is a timeless firearm?

Winchester 94

Colt SAA. Always has and always will be the quintessential six-shooter.

I'd have to agree with Remington 870, Browning superposed.... and Marlin 39 (for a .22) are ones that come to mind immediately.

1911 .45 acp
101 years and still going strong

98 Mauser. Pretty much the standard bolt action design and not likely to change anytime soon.

I tend to consider Actions more so than firearms themselves. Revolvers are timeless. The Henry Rifle started the Lever Action ball rolling for all the other Timeless Lever Actions that will be mentioned so I guess the Henry is a Timeless firearm.
The Mauser Action was a watershed for Battle rifles of its era so the Mauser 98 has to be right up there.
Then there is the 1911, without it most other Semi Automatic Pistols would not have happened.
The Garand and the Kalashnikov, are two more weapons that revolutionized firearm design.
Not certain what else I would add to the list. But those cover modern era weapons pretty well.

American made Lever Actions and Smith&Wesson revolvers.

We are lucky for classic guns to go with the 2nd A. My list of classics are:

The flintlock Longrifle
The lever action rifle
Colt Single Action Army
Colt 1911
Thompson submachine gun
Browning .50 cal machine gun
S&W .38 special snubnose
M14
12 gauge pump shotgun
12 gauge coach gun

Some of these are categories rather than specific, like (Henry, Winchester and Marlins) for levers and the (Rem 870 and Moss 500) for pump.

But the are guns that when I see then I saw "Hooray for our side!"

^when I see them I say...

I guess I'll be the first one to say it: AK-47.

Definitely would name the Browning .50 cal M2HB. That gun has been made essentially unchanged since 1921 with the exception of the elimination of the water jacket, and it is still being used by our military forces around the world today.

Internationally I'd go:

British Brown Bess
Napoleon 12 pounder
Mauser 98
Broomstick Mauser
Luger 08
Enfield .303
Walther PPK
AK47
88 mm Panzer cannon
Glock 17

PPK started the trend of a easy to carry pistol.

Maybe drop the Enfield for the Maxim or Lewis?

I'll be another to say AK47. And also any single shot 22. They are handy little rifles

You can almost answer this by looking at the platforms with the most aftermarket accessory support.

Ruger 10/22, AR-15, 1911, Remington 870, Mauser 98, and the Glock.

With the exception of the Glock, all of those are 50+ years old, and the Glock is 30 years old, yet all remain popular and commonly used. I personally think all (including the Glock) have been technologically improved upon by other designs, but none have been so outmoded as to make them useless.

m107 never found a target i could not miss. not gun

Each brand has some iconic hold overs that are solid pieces. Marlin 39a and 60, Ruger GPs and Mark series, Colt 1911s and Snake guns, S&W mod 10s. You just have to know what you like.

+1 for the browning 50 cal machine gun. To my knowledge, its the longest serving weopon in our military history. I'm glad I got one. Lol.

For shotguns I have to throw in Winchester model 12 and Browning A5 as my favs.

Remington Rolling Block.

Break open shotguns.

The Mauser action and anything that basically uses Browning delayed blow-back locking system.

Marlin mod 60 is a tough gun and usually accur.