I heard that Lever guns are less durable than bolt actions when it comes to high pressure loads, is there any truth to this?
Lever guns are fine durable pieces of machinery when used within their design limits.
You exceed the design limits of a Bolt action, or a lever gun, and the metal is going to stretch. You stay within the design limits, then the durability is determined by other things, basically the "robustness" of the parts.
You can expect that things that have a lot of screws and straps, those things will unscrew and work loose. Lever guns have a lot of screws, so you will need to watch them so they don't fall out.
The cowboy action shooters can tell you which lever actions can be cycled a lot without parts breakage. I am certain that old established designs, like the Marlins and Winchesters can take a lot of use. Modern metals have made these actions even stronger. But there are limits.
In my opinion, the M98 Mauser is one of the most durable robust firearms mechanisms ever built.
99% of lever actions are rear locking mechanisms. Most bolt guns are front locking. A rear locking action stretches more than a front locking action, and thus a cartridge in a rear locker gets stretched more. It is the case that is the weak link in any action. When the cartridge breaks, all hell breaks loose, regardless of action.
Don't worry about your Marlin. Shoot loads within factory pressures, tighten things that get loose, lubricate parts that need lubrication, and replace any parts that break. When your barrel has lost its rifling, it will be time to rebarrel.
Which at 200 rounds a year should be 25 years. Assuming FMJ's and a 5000 round barrel life.
24.0 grains is the published max from Hodgdon and it runs 36,200 CUP.
