I have a old Marlin rifle the only things i do know is that it is a .40 cal, and its serial # is less than 3500. I dont know much about it and would like to know more anybody out there with info please help!!!

Without a bit more information, I'm afraid no one is going to be able to help you. The model number and type of action would be a good place to start.

it is a lever action, as far as the model # i will have to look,tonight i will get a pic of it and post it up here

There were a bunch of 40 caliber rifles in the late 1800's, nearly 4 dozen! Most were chambered for single-shot target rifles, though.

There was one that had a Marlin label, though - the 40-60 Marlin. I think this cartridge was designed for Marlin's lever actioned rifle. The few pictures I've seen of the 40-60 Marlin cartridges had a low number ogive, probably less than 2 or so, and were flat nosed. Most of the Singleshot rifle cartridges had longer ogives and were of roundnose design.

There were four 40-60 chamberings, all of them used different cases, the 40-60 Bullard, the 40-60 Winchester, the 40-60 Maynard, and the 40-60 Marlin. Unfortunately, I don't have any specs for the cases. From what I can gather, if the rifle is shootable, a chamber cast should be done and the barreled should be slugged to find what size of bullet is required. The books I've seen have recommended everything from a .396 diameter bullet all the way up to .409, however it seems like most required .406 for best accuracy.

Sorry, that's about all I know.

The .40-60 Marlin is the best bet.
The .40-60 Marlin is the same as the .40-65 Winchester, loaded a bit lighter. Bullets were 260 grains in each, 1385 fps for the Marlin, 1420 fps for the Winchester loading. The .40-60 Winchester case is shorter and the .40-60 Maynard case is longer.

You can make cases by necking down .45-70 brass if the base diameter is .505" or less. Some lots are too large. ( I should look that one up and double check.) Rim diameter .604"
Case length 2.11"
Overall length 2.55"
Neck diameter .425
Bullet diameter .403" but you may need larger.

Bye
Jack

it is a lever action and is in shootable condition i would imagine i will probably never shoot it,and when you guys metioned .40-.60 i do remeber my grandfather telling me something about .40-60 or .45-.65 but on the barrell it just says .40 cal. thanks for the info i will be posting some pics. in case i am missing something

I have a old Marlin rifle the only things i do know is that it is a .40 cal, and its serial # is less than 3500. I dont know much about it and would like to know more anybody out there with info please help!!!

If it is a singleshot rifle, most likely it is a Ballard manufactured by Marlin. If it is a lever action, tube magazine repeating rifle, most likely it is a Marlin Model 1881 made in 1883.