98C hammer binding when screws tight

I've got a 98Custom (it's my wife's actually ).

When the rear two screws (the one above and the one below the cocking arm at the back) are tightened, the hammer binds to the point that it almost can't move. In fact, if they're REALLY tightened, it can't move at all. The screws have to be loosened to a point where the hammer moves freely, but that leaves the screws too loose for my comfort.

Anyone else had this problem and/or have any suggestions?

I'm considering using some sandpaper to "ream out" the insides of the receiver halves a little bit.  I've seen talk in the polishing internals threads about going too far and air loss from that, but it seems to me like it's not sealed back there anyways.

Any dangers/things to watch out for if I try that?

Thanks.

You could do the same thing as polishing the internals, but take out alot more metal. Like you said. But you wont get any air loss persay. The bolt seals in the valve so it will still be able to cock.

Just make sure you dont take off too much, or else you will have alot of slop in the bolt which could cause a cracked valve/powertube.

Ive heard of some people using washers in between the receiver halves, but Ive always thought that sanding/steelwooling the internals would be better.

Well, seeings as they are cast and not milled, imperfections come out.

They do test them after they are built, but some may slip by.

Definatly go with the sanding, it will feel alot better in the end and you wont have to worry about losing a washer when you stip the gun for reutine maintenance.

You said :

 "I'm considering using some sandpaper to "ream out" the insides of the receiver halves a little bit.  I've seen talk in the polishing internals threads about going too far and air loss from that, but it seems to me like it's not sealed back there anyways.

Any dangers/things to watch out for if I try that? "

Bruce A. Franks suggestion is the best so far , and it is basically "Polishing the internals" .

Look for some "Witness Marks" as Frank described , and see if there isnt some burr of metal  or debris somewhere first thats easily removed before you attempt modifying or removing any material from inside the castings of the marker .

If you decide to Hone out the inner diameter of the casting , the section the rear bolt moves in ,is relatively small lengthwise , so while it will be tedious , it shouldnt be too dificult . Remember tho,, its just Diecast aluminum , so its relatively soft metal , and from what you describe , its "Almost moving" when assembled , it shouldnt take much removal of metal to get it cycling smoothly .

I'd rather have you complain about having taken an hour to fit with 400 or 600 grit sandpaper , Than have you take 60 grit sandpaper to it and 15 minutes later determine you've taken too much metal out . You can always sand it a little more , my preference would be with 1000 grit wet or dry carborundum paper (Use it wet , it doesnt clog the sandpaper ) for finishing the fitting when you get close .

If you have the equipment (drill , dremel tool ) and a way to do it , a little bit of rubbing compound , available at any automotive store , on a dowel wrapped with a piece of Tee shirt would make it less labor intensive .

Here's the tool I've used for honing and polishing bores , including the recievers , you can put scotchbrite , sandpaper , or a piece of cloth in the slot of the bar , also the rod can be made from a wooden dowel

Edited by Shadowminion - 15 October 2006 at 10:54am

NONE of the screws in the marker need to be tighter than you can accomplish with pressure from the short arm of the Allen wrench.

If you think the screws are binding before they become "tight" then it is possible that you have actually damaged the threads with previous over tightening. You might find that replacement screws from a hardware store, Allen screws and nuts, will improve the hand tightening process. Standard Allen cap screws have heads that are a little taller and stronger than the Tippmann screws.

UV Halo wrote: I think he means that the hammer is binding before the screws are too tight.

Correct.

It's definitely NOT a stripped or damaged screws from overtightening problem.   I like my screws tight, but I've got FAR too much mechanical experience to actually damage anything.

Anyways...

I took it apart again last night to work on it.  First I wiped all the oil off of it with a paper towel, then put it back together with just the hammer in it, tightened it down to where the hammer could just barely move, then forced it back and forth a few times.  This gave me a really good indication of where it was wearing/hanging up in the receiver.

I used some 220 grit sandpaper, because I didn't want to take off too much metal at a time or scratch too deeply, and it took quite a while of sanding, testing, sanding, and testing to get it to a point where it was acceptable.  Then I finished it off with some 600 grit to keep things nice and shiny. 

It's still not the way I would like it to be, but I can live with it at this point.  It's still about 20 degrees from as tight as I can go holding the small end of the wrench (meaning if I can tighten it to 6:00 on a watch face, I have to back it off to 4 or 5).  Again, not as tight as I would like it to be, but at least I won't worry about it so much now. 

My biggest problem, I guess, is that it's my wife's gun.  If it were mine, I would probably just deal with it and keep an eye on the screws to make sure they don't loosen up.  Since it's my wife's, I want it to be as foolproof as possible, so she doesn't have to worry about anything.  I've already found the screws on the ASA loose before, and had to tighten them up for her - she hadn't even noticed.

My suggestions would be use steel wool or a dremel, and lots of oil. I know you have already worked on your wifes 98, but if you still cant get it to work try using playing cards or paper as micro-spacers or something.