Help with a belt mountain base pin!

[Waffen]

Gentlemen,


I reacently received a Belt Mountain base pin and I'm having a bit of trouble installing it on a Ruger New Model Blackhawk. It seems that the pin fits the cylinder snug as a bug, however it just will not clear the first frame hole (the one with the base pin latch). It goes in about 1/2mm and thats it.

I know I probably need to lap the holes in the frame, but how do most of you go about doing this? What material should I use and what tools will I need to do this?

Any help is greatly appreciated. It's obvious this belt mountain base pin is superior to the factory one and I want to use it bad!

[John R.]

They are always super tight when new. A little oil usually works.

[44 Man]

I tried one of those once.  It seems they are a tad oversize to tighten the gun up a little.  I was never able to get mine into the gun frame either.  I ended up giving it to a friend.  Hope you have more luck that I did.  44 Man

[safetysheriff]

the base pin is an 'interference fit' in some respects.   i hope this all makes sense, therefore.

because of what we did at ford motor co' years ago to make replacement valve guides fit into the new cylinder heads i recommend this:

put the base pin into the freezer and let it get cold.   put the revolver frame and cylinder in front of a warm-air register or whatever.   this will, as you probably know, shrink the base pin and slightly expand the revolver's cylinder frame.    then i'd lightly lube the base pin with a synthetic motor oil and tap it into the frame with a lightweight metal mallet.   then when the cylinder is lined up with the pin you can get the pin tapped into the frame at the back end of the cylinder.

my base pins were tight fitting but with a little lube and a little use of a hammer they were seated.

i like 'em a bunch.

take care,

ss'   

[EdK]

Wow - sounds like a good tip but also a semi-permanent installation. What about cleaning, etc.?

[Tom C.]

I have put Belt Mountain base pins in about a dozen Rugers, Blackhawks, Super Blackhawks, Vaquers and 50th Anniversary Blackhawks. Most slipped in, usually tightly. A couple required lapping to fit. I used the original base pin, with medium and fine lapping compound from Brownell's to do it. Didn't take too long.
Not only can the holes be a little tight, they can also be slightly misaligned. The small base pin Ruger uses take care of that. The Belt Mountain pin brings some of these faults to the fore.

[Lloyd Smale]

Toms got the answer

[safetysheriff]

Wow - sounds like a good tip but also a semi-permanent installation. What about cleaning, etc.?

the first installation was by far the toughest in each revolver.   afterward the pins moved in and out more readily.   to remove the pin i loosened the set screw and grabbed onto the exposed end of the base pin with channel locks.   i held the muzzle upward with the channel locks holding the base pin/revolver over a carpet or mat.   i then tapped on the channel locks hinge pin with a hammer to get the base pin out of the revolvers frame.   kind of like the way you can grab a very tight pin at the top of a door hinge and remove it the same way by tapping on the hinge pin of the channel locks.

after this was done a couple times it was no longer a problem.   everybody is entitled to their own opinion, but i don't see many of the Ruger revolvers as having problems with the alignment of the base pin openings in their frames.   their revolvers are generally accurate, and even more so in many instances with the installation of these base pins.   i think the original pins are somewhat on the small side to allow the cylinders to rotate a minute amount to aid in line-up of the chambers with the barrel/forcing cone, such as is explained elsewhere on the web by one of the revolversmiths.

i don't see much to be gained by introducing lapping compound into the revolver's frame.  i'd rather put some 600 grit wet/n/dry paper to use on an oversized pin instead.   then i'd wash it down with brake cleaner to remove the grit.   

to each his own,

ss'   

[Waffen]

I thought I would post an update to help people in the future that had this problem.

I ended up stripping the pistol down to just the frame, then taking the stock base pin and chucking it up in a cordless drill. I then applied "valve lapping compound" to the stock pin and inserted it into the rear hole. I opened it up VERY slightly. I went very slow, often stopping to clean out the hole and try the belt mountain pin for fit. Once I got the rear hole where I wanted it I had to move on to the front hole (in front of the cylinder, under the barrel). I had to do this portion by hand. I simply removed the base pin latch, and the ejector rod housing assembly and worked the stock base pin in and out of the hold with valve lapping compound. I did this for several hours. I finally got the fit I needed. I also chucked the belt mountain base pin in the drill and applied lapping compound to a rag and spun the pin for about 5 minutes. After doing this I did acheive a truly custom fit.

With the cylidner out and the base pin locked into place, it now feels like it's part of the frame. There is no more movement, or play in the pin like there was with the stock pin. I can't tell if it helped accuracy wise because I added a Wolf 30oz trigger spring which lightned the trigger pull a lot. (much better than the poor boy's trigger job). I was shooting 1.5 groups at 25 yards off a rest so it didn't hurt accuracy. It just makes the gun feel more like "one peice of steel". I would definatly buy another.

You can find the "valve lapping compound" at your local auto parts store. I went to "Autozone" and it was listed as "Valve Grinding Compound". It seemed to do the trick.

Hope this helps.

[Old Griz]

I used super fine wet/dry sandpaper on the pin—not the gun. Not about to risk messing up my frame. The pin is cheap. Still tight, but I can get it in and out.

[BruceP]

I did like Griz and just lapped the pin to a very snug fit to the frame. This did leave the cylinder with a looser fit than the frame but still a lot tighter than the factory pin.

BruceP