Look under the do it yourself gunsmith section lot's of good sticky info, I suggest you disassemble and clean before anything else to remove the left over machining residue, as well as the preservative oil etc put on at the factory. I do this with all new to me firearms, new or used as you can inspect before firing as well (links below). As far as barrel break in... I suggest shooting 5 and clean, then 10 and clean, keep it at 5-10 rounds then clean until you see a decrease in copper fouling. Use a good copper removing cleaner, bore foam etc, what your trying to do is smooth the bore/throat area machine marks, and clean the copper/fouling before building up to let the copper bullet smooth the machine marks. It will happen regardless, but cleaning every 5-10 rounds will reduce the amount of copper build up, and possibly break in faster this way. I'm not sure how much actual good this does, if you shoot 5 rounds clean, then 10 rounds clean, then 15, 20 that should take care of any barrel break in procedure.... just use a good copper remover, bore foam if you want to do a barrel break in...cool between shots don't let barrel get to hot.

Far more important in my opinion to disassemble, clean the action etc from any machining work left, and the factory preservative. Use a good oil of your choice, as well a good rust preventive ( I prefer eezzox for rust for preventive)

I use a cleaning rod for cleaning, good brush, jag, and tight fitting patches make cleaning much easier. I use a boresnake before shooting to remove any oil/residue in the bore, also for a quick cleaning if needed, but much prefer the cleaning rod for real cleaning.

How to Disassemble and Clean
http://www.marlinowners.com/forum/h.../how-disassemble-clean/55799-model-336-receiver-marlin-s-sequence-assembly.html
http://www.marlinowners.com/forum/how-disassemble-clean/37660-basic-marlin-336-field-strip-video.html
http://www.marlinowners.com/forum/how-disassemble-clean/20184-disassembly-assembly-1895-pics.html (says 1895 but works with 336 also)

search youtube for 336 disassembly instructions, note where the screws come out of the receiver..snap a picture with your phone where the screws go as you take them out, or lay them out at the threaded hole they go into and snap a picture. DO use a good set of gunsmithing screwdrivers, if you don't have any walmart sells a set that will get you going.

hope this helps, and congratulations on your new marlin... welcome to marlinowners

 

TacoLoco, get some JB Bore cleaning compound before you shoot the gun and a cleaning rod that fits your bore. Using a jag wrapped with a piece of blue shop towel, rub the compound onto the towel and run up and down the bore like 50 times, being careful not to let the cleaning rod hit the sides of the bore. Once done, cut another piece of shop towel and compound and repeat 50 more strokes. This will clean the bore to a shin you will not get with 500 firing and a lot cheaper. It gets all the small pieces of material out of bore and will make cleaning lot easier too. I never fire a shot in a new gun until I do this procedure. You will break it in without all the cleaning process from one shot and clean. Think You Tube show this if you will check. Brownells or Midway stocks JB products, and a small jar will last years. Best investment you will ever make to break in a new barrel.

 

I don't do the rigamarole. I just shoot the gun.

 

OP, they need very little care and maintenance. Less is more. Run a patch or two down the bore before you shoot it. Clean the bore again after shooting if it will be stored for awhile. Mist a soft cloth with a bit of oil, and wipe down the outside before putting it away. That's about it. It will last a lifetime, and then some.

 

I buy the rifle, clean the rifle, then shoot the rifle and clean it again when I get home.

 

Clean the bore with a nylon brush and mild bore cleaner like hopes. Spray a little lube like rem oil on the bolt. Go and sight the gun in. Run a little lite lube like hopes foaming cleaner down the bore. If it is a hunting gun run a little oil as a preservative down the bore and put away until until deer season. If a bench shooter shoot a couple hundred rounds then refere to the first couple of posts.- Locoman

 

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Years ago I bought two new Remington heavy barrel Varmint 700s in 22-250 caliber, one for me and one for SWMBO. We cleaned the factory grease out of them and did an elaborate barrel breakin process with one and just shot the other and cleaned both the same when we got home. The barrel Breakin was an absolute waste of time and ammo.....never done that on a new gun since that time. Oh yes, both those old Remington Varmint rifles will shoot one hole groups at 100 yards. No detectable difference in the breakin barrel and the one not.

Do the breakin if it makes you feel better......but the gun doesn't care. The JB's treatment mentioned above will help, I have used a fine lapping compound to hand lap a barrel....does improve accuracy ....sometimes.

 

Read the manual............
Learn about your new weapon.....
Go to youtube for the "how to`s" on cleaning . Audio/visual available.

 

You really should disassemble the rifle and clean it before you shoot it, I've seen Marlins that never were stripped down and cleaned and the old grease turns into sticky gummy mess that holds dirt/dust and just makes things not function as well as it should. Nowadays with Remlins you need to be especially careful because the few I've opened up were loaded with metal shavings mixed in with the little bit of oil from the factory. Plus, it gives you the opportunity to file down (using sanding stones) any rough tooling marks on the lever and/or lifter. It can smooth things out nicely! Also, you will want to clean the mag tube, lots of junk in there usually, grease, metal shavings that make the plastic follower stick and that can cause jams.
As already mentioned, the "Do it yourself gunsmithing" section details how to disassemble and reassemble a Marlin, it is very easy. Just make sure you have the right screwdrivers for the job! I recommend Grace screwdrivers, but you can go with whatever brand of gunsmithing screw drivers you prefer!
Good luck with the rifle!
mazer

 

A good degreaser for a patch or bore snake is Lighter fuel,pure and evaporates leaving no residue. Comes in handy cans with a spout. Tip I picked up from the accuracy international web site. Helps with first shotaccuracy from a cold barrel on a number of guns.

 

One of the slickest 336's I have owned is a 80's cheap model with birch stock, but the action is very smooth, and shoots well also. I broke it down and the preservative had turned to a brown gunk that was like varnish... metal shavings inside receiver etc also, and the inside of the magazine tube was horrible brown gunk coated everything. I used odorless mineral spirits to remove this gunk from everything, lighter fluid also works well, but does leave a film after flashing off... if you use mineral spirits be sure to go behind that with a solvent or oil immediately so that it doesn't rust. I also use wooden shish kabob stick and a good brand of cotton balls (make cuts into the end of stick wrap cotton ball pieces around it, and break into lengths needed) q-tips etc and a tooth brush or similar to get the cracks and corners, you will be amazed as the gunk and mess that comes out of a receiver no matter if it's new or old, JM or REM. Use a good oil or grease in the areas that need it, I prefer dry lube to cover inside of receiver makes cycling very easy, easy to clean, doesn't drain back to the buttstock discoloring and rotting. I also use eezox for rust protection, and for hunting guns use it only it's a dry lube with outstanding rust preventative, and is also great for the bore when cleaned down to the metal it prevents or lessons first shot flyers, and reduces fowling. Rem oil is a nice lightweight oil for breaking in the action if you want to cycle it a bunch to smooth things out.

On the outside of the firearm I recommend eezox or a good wax for a rust preventive. I hope I didn't overload you with info, you will find what works for you by trial and error, and what you like the best as far as ease of application, how well it works etc. Remington owners manual should also show you points that need lubrication as well as the previously mentioned websites, and links etc.