Rolling Block: How much clearance between pins and hammer or block?

[palouse_2]

I cannot find a reliable reference suggesting proper clearance between rolling block receiver holes and pins, and between pins and block or hammer. What should it be?

My "new" #1 late version 43 carbine has too much slop between pins and hammer and/or block. Bore, stocks, receiver, and other parts are worth salvaging to make a shooter. Mail ordered in the early 1960's, it's been sitting in a closet unfired since. Likely hammer and block are from another carbine, loose on the pins enough that there is play in the block when hammer is fully forward. Having other RBs without any play, I consider this carbine has too much to shoot without excessive wear.

Best option appears to be: have new pins turned to fit, and receiver holes reamed to fit the pins. Matching new pin diameter to what is proper for current hammer and block hole diameter(s). However, I need to give machinist dimensions and tolerances.

Using caliper on pins, and a pin gauge set on holes, there is 0.003" to 0.004" clearance. I obviously don't want press-fit, being too tight. Is 0.001" clearance too much? Is 0.0001" correct? No internet source for info, and I don't currently have access to my other "good" military RBs to take measurements.

Numrich, Pedersoli and RollingblockParts have been checked. All holes appear to be round, not pear shaped or worn.

Thank you for your help.

[marlinman93]

Can't say I've ever checked clearance for new pins I bought or made? I simply make them as close a fit as possible, but no friction that makes the pins snug enough that the movement of the hammer or block makes the pins want to move also. I just polish the pins until the block/hammer moves freely on them.
Pin sizes vary, so I don't try for a certain size. I measure the old pins and after making new ones I polish them until they fit. Only had to open up the receiver once after making new pins.

[wlw-19958]

Hi There,

I've resisted answering this question. I haven't measured the clearance
between the pin and the hole in the breech block or hammer. So, I don't
know what the Factory used for the range of acceptable clearance for
these parts. I would measure the old pins in several places to determine
the original size and how much wear has taken place.

Now in standard machine shop practice, for a sliding or rotating parts of
this clearance would be in the .0005" to .0010" range. But this doesn't
take into account dirt and fouling that would get into the mechanism so
an additional 1 or 2 thousandths of clearance would probably have been
used to lessen this effect. It would be interesting to go through and
measure the clearances of some excellent condition rifles.

Cheers!
Webb

[palouse_2]

Well, that will teach me to take too long to type a reply. System logged me out, I lost a detailed reply.

The summary:

marlinman93,
You are correct. Changing the pins and polishing them to fit is better than also changing (reaming) the receiver holes. I will likely try "polishing" with a field expedient lathe, and my action/polishing stones.

The hesitation is/was that the hole through the block is very slightly tapered, as demonstrated by being able to get a specific pin gage partially (2/3rds) through the hole. The hole also feels "rough", which was another incentive to ream the block hole. To "clean up" or make the bolt hole parallel-sided by reaming, I would also need to expand/ream the left side hole.

While not pretty, I believe that I can make the carbine a nice shooter. Worth the relatively small effort. I believe that the bolt and hammer are correct for the RB model, but they are likely not original to this receiver. Parallel vice jaw marks on both sides of receiver suggests a rough time during depot maintenance, and lack of concern about hand-fitted parts. The carbine was purchased in the early 1960's from a California source advertising dirt-cheap prices in sporting magazines. The previous owner said that his father put it into the closet immediately after it arrived, never fired it, due to lack of 43 Spanish ammo.

Webb,
I agree, clearance would be preferable at .0005" to .001". If I shoot so much that it gets sticky from fouling, I will try to stop grinning like a goon, simply wipe down the carbine with a damp cloth, and continue.

On a recent trip home, I recovered two Swedish RBs from storage. Both have bolts and hammers that when opened or cocked feel like a sharp knife through butter, and lock up without any play. Smooth.
Using pin gages for the holes, and a cheap caliper on the pins, clearances are on the order of .0005" to .001". Pin to receiver hole, and pin to bolt or hammer hole.

All pins, good rifles or subject carbine:
- The right end of pin is smaller than left at the head.
- Most interesting is that a respective bolt/hammer pin cannot be inserted from right to left. The last few thousands of the outside of right side hole is smaller than the inside portion of right hole. The pins are designed to fit tightly in the right hole. Imagine having a hole you want to ream an extra .001" wider, and using a square bottom reamer. Such reamer still has a slight bevel to the end. As you ream the hole left to right, you do not ream all the way through. Leaving the last few thousands original diameter. In the case of these RBs, the pin sticks out from right side hole because pin tip itself is beveled smaller than limitation on right hole.

Using a pin gage, I was able to insert from left through action and through most of the right hole, being stopped for lack of clearance just a couple of thousandths before pin gage was flush with right surface.

I am set. Thank you for your help.

[wlw-19958]

Hi There,

I'm glad you have the information you needed. Just a side
note, I'm not sure I would choose a Swedish made rolling block
to be representative of the Remington product. But your notes
are interesting.

Cheers!
Webb

[marlinman93]

When I make pins I use a piece of round stock in the lathe and leave it long while turning so I have extra to hold in the chuck. I don't cut the head or length off until I polish it to fit. Then once it's polished down with emery paper to a perfect fit I put it back in the lathe and cut the head and finish the pins.
I also keep old pins and have an assortment as sometimes a used pin works in another Rolling Block and was loose in a previous one.