MarkB, very nice work there, you did a craftsmanship job on that Marlin. If that is your first gunsmith job, you sure pick a fitting subject and did a very good job, congrats to you. Take care, enjoy the fruits of your labor. Just keep on keeping on, John.
I'm late to the review; just joined MO. Great pictoral documentation of the mods. I'm considering doing the same project on my 1974 model 336, but going to 18" length.
The part I wanted to see most is the marking, drilling, and tapping for the front sight. I've done flat surface drilling and tapping, but I haven't tried to tackle a barrel. I'm sure it requires a good center punched starter detent. I would also assume it requires a drill press. How difficult was that part of the job?
First, welcome to MO. You will like it here and you will find all the info and advice you ever wanted.
It's easier than you think. I used my eye to position the front sight. I wanted the front edge of the ramp about 1/8" behind the barrel band. I marked the position with a pencil (the lead wipes off). I placed the ramp with an old front sight in it on the barrel and just moved the ramp sideways until it looked vertical when I sighted down the barrel. You will be surprised how accurate your eyes are! When I was happy with the position I taped the ramp to the barrel. With the ramp in place I then marked the screw hole position with an auto center punch (press on the punch and it snaps and marks the hole - Starrett) through the screw holes of the ramp.
Now, the standard front sight screw is a 6-48 thread. That needs a #32 drill hole to thread. You have to be careful not to drill too deep into the barrel so, I put the #32 drill bit into the old front sight hole on the cut off section and slid a drill stop collar onto the drill bit until the collar was flat on the barrel. I pushed the drill bit into the hole as far as it would go and tightened the collar to hold it in place. This keeps the drill bit from going too far into the barrel. I used a hand drill to drill the holes. The drill collar worked perfectly and stopped the drill bit at the same depth as the factory screw holes. The drill was the only power tool I used.
I used a 6-48 bottom tap to hand tap the threads. A normal thread tap has a long section that eases into the thread while the bottom tap has the thread cutters almost to the end of the tap so the thread goes deeper into the hole when it bottoms out. Just remember to use oil and, after every 1/3 turn or so of the tap, back out the tap to cut off the burrs from the threading cuts. You don't need too much force to cut the threads so be careful to stop when the tap hits the bottom of the hole.
At this point just blow out the holes and install the front sight ramp and then the front sight.
I have to admit to an error I made. When I marked the position of the holes I measured and thought I did a good job but when I mounted the front sight it was off just a little to one side. I had to file the one edge of the holes to move the sight vertical. I wasn't much but that was when I realized how accurate my eyes are (instead of measuring). The other option would have been to drill a second set of holes to right the sight. This was my first attempt at something like this and I learned a lot about what to do and not do.
Also, after "eyeballing" the sight vertical, I now get good groups where they should be with no front sight adjustment and minimal rear sight adjustment. Eyes work good.
Nicely done, very impressive indeed. Little late to the party as just recently joined MO. Now have a good base in case i grab a project gun, Luckily for me my 336 i just picked up didnt require anywork, well cared for 96BOD, may do some light tuning to it but thats prolly about it, if it even needs it? will know for sure in the next day. Anyhoo just wanted to give ya props for a nice job and a very good template for anyone wishing to start a project gun.
I did 1 a while back just like yours only I didn't refinish the stock or put the sight back on. I use a scope and until I decide to put peep sights on it or something the sight won't be there grabbing vines or whatever I am walking through. The sight is a simple install and I have it put up incase I decide to put it back. These little short guns are great handling guns. I have 7 336's in 30-30 and used my worst one for this project being the first attempt. I wish I had done a better looking rifle but it's fine and shoots great. Also I cut my magazine tube also and put it back the same amount it was from the factory and put a 11degree target crown on mine.
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