[Grim Peeper]

I own a older model 39a and I was shooting it at the range today and I put about 100 rounds down range when I noticed that the thumb screw that holds the rifle together was coming loose after 30 rounds or so. My question is that I was wondering if there was any way to secure the screw for shooting and to make sure that it does not come loose when fireing I was thinking of possibly useing a thick rubber washer to keep it tight, has any other marlin 39a owners had this problem if so how have they cured it. Thanks for any input at all.

[az_imuth]

I use a large coin to get the screw good and tight. After working the lever a few times I snug it up again and it's good to go. Neither of mine (a '54 and a '72 model) have any type of washer and they both stay tight no matter how many rounds I run through them.

[Carl N. Brown]

My problem is getting the thumbscrew loose when I do a periodic thorough cleaning! (Maybe once every two years.) I snug the thumbscrew up with a 50 cent piece and it stays snug for years.

My cousin had a functioning problem with his because the last time he had cleaned it, he had not fully tightened the thumbscrew and the two receiver halves were not tight. Once the screw was fully seated there was no problem.

[cottswald]

Adjusting the thumb screw on a 39a can be like choosing ammo. Each individual rifle has it's preference. Some rifles are pretty finicky regarding lever function and proper cycling (feed, extraction etc.) depending on thumb screw tension. Barring any previous damage to the reciever, I would think a tad bit more tension on your thumb screw would be warranted. Try it and see how she does.

[Grim Peeper]

But I read somewhere that you should not over tighten or tork the screw to tight is that BS? What do you mean use a coin? under the head of the thumbscrew?

[rcmodel]

The screwhead has a large slot in it.

I made a large screwdriver to match it.
But it was designed to use a coin to tighten it.

I tighten the snot out of them, and they never come loose unless I want them too.

But as cottswald said, some Marlins won't operate right if the take-down screw is over-tightened.

Didn't seem like much of a problem on older guns. But they were better fitted them more recent ones.

rc

[Grim Peeper]

Well this 39a is from 1947 so i guess ill just take your advice and tighten it alot if you say it wont hurt it. Thanks!

[cottswald]

Many folks use a coin to tighten the take-down screw. It's considered sort of a feature, especially useful back in the day when a lot of folks didn't carry expensive tools, but most everyone had a coin or two in their pocket. As mentioned by rcmodel, I also like the use of a large screwdriver. It fits the screw better and won't cause stress markings on the top of the slot as is the case when using a coin.

The size of the screw driver is more for fit rather than torque. Overtightening can cause undue stress on the action, possibly even casue it to bind. Too much slack on the other hand has its own problems regarding improper fit. Either extreme can create problems with extraction or feed, and over time cause unnecessary wear. As mentioned earlier, your rifle will let you know. If you're rifle is functioning properly (no problems with extraction or feed) and the action cycles smoothly, then you've probably got it right.

In your case Grim Peeper, being that it's an older model and has seen some use, I would take the screw completely out and ensure that all the threads are in tact and none have stripped. Then clean both the screw and reciever threads with a good solvent. Add a tiny amount of lubricant and then tighten firmly by hand. If it still works loose, try adding a little tension with a screwdriver (and I mean a little) like maybe 1/16 of a turn if that.

Remember, each rifle can be a little different. Some like it tight and others don't. Kinda like wo.........., uuugh, never mind!