Belt Mountain base pin on new revolver

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JimMarch1

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Feb 19, 2007
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Think about it - Before the pin, it was relying on looseness to function!

Not the first time I've heard about particularly sloppy specimens not being compatible with a BM pin.

I've heard one report that it worked well without the set-screw locked down, but with it down a mis-alignment occurred. Don't know for sure but I'd be willing to bet an owner of that piece let the base pin jump every once in a while, reset it by hand and kept shooting. That would booger the hell out of the front frame hole for the base pin.
 

Short Barrel

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Mar 2, 2006
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I like the BM basepins and have them on a few guns.The thing you have to remember is that Rugers are high production,factory guns and aren't put together with one cylinder line bored to that specific gun,like Freedom Arms does or Bowen and other custom smiths due.When things are built that precisely,the tight base pin helps keep them in line.

Rugers a purposely built with some slop,as the mass produced parts aren't as precise and if chamber and barrel aren't as perfectly lined up,like a line bored gun,the bullet hitting the forcing cone,can tweek things that tiny bit and many of these guns shoot very well this way.Now,if a Ruger happens to have some slight misalignment,and you take out that slop,using a tight fitting basepin,you make it worse,not giving the cylinder a chance to move slightly and line up properly with the bore.Now the the bullet is going to shave on one side as the cylinder can't move laterally to help align itself.

This is why a Belt Mountain base pin may improve things,they may stay the same,or they may be worse.You just have to try it to know.A good set of range rods could work some of this out beforehand.I don't know if Iowegan still makes them,he had stopped at one time,but if you can get them,they are heads above any range rods I have seen.

Try the BM baspins but if it makes the gun wose,take it out.Use it in another gun or find someone who needs it.I have some guns that didn't shoot any differently with them,but I like the locking feature for insurance with hunting loads and I can pick the style head I like for a particular gun.
 

REP1954

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Jul 21, 2008
Messages
959
When you fit an oversized base pin the diameter is not the only concern. The relief cut out for the cross pin needs to be addressed as well to make sure it is not to tight. If you make it so it has just a little movement to it when it is in place then it should be good to go. If you want to use one with the set screw then you must add a detent to your barrel for the screw to enter into and you should not make tight the screw down against the barrel but just let it fill the detent enough so it will not let the base pin move out forward. I think to many people buy these things and dont take the time to fit and use them as they should be and then become disenchanted with an otherwise very good product. I dont like to use the set screw as system to hold my base pin in and rely more on a heavy duty cross pin spring.
 

Yosemite Sam

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Mar 18, 2002
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Cape Cod, MA, USA
JimMarch1":1quvmdtk said:
Think about it - Before the pin, it was relying on looseness to function!

Not the first time I've heard about particularly sloppy specimens not being compatible with a BM pin.

I've heard one report that it worked well without the set-screw locked down, but with it down a mis-alignment occurred. Don't know for sure but I'd be willing to bet an owner of that piece let the base pin jump every once in a while, reset it by hand and kept shooting. That would booger the hell out of the front frame hole for the base pin.
I bought a used SBHH with a BM pin installed. I was still having problems with it jumping the pin, so disassembled and found not a deformed frame hole, but the base pin latch (screw and cup assembly) was badly deformed and worn.

In fact, I also experienced transfer bar hangup because the set screw divot was drilled too close to the frame. If you tighten down the screw it forces the pin into the transfer bar, causing the action to lock up. I "solved" this by only screwing the set screw in enough to nest in the divot, without tightening and pulling it in.

A new base pin latch assembly, heavier spring, and not cranking the set screw down fixed my issues.

-- Sam
 

J Miller

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Not in IL anymore ... :)
Bkat":jd584yg6 said:
Joe,

Can you tell me what's included in Iowegan's range rod kits and do you know if he still sells them?

Thanks,
Bkat

Here is a diagram of Iowegan's range rod:
img001.jpg


The diameter of the rod is very precise and keeps it aligned with the bore. When you slip the rod into the muzzle the little reference peg matches the feeler tip at the end of the rod. If the feeler tip catches the edge of the chamber mouth you can tell if the cylinder is high, low, left or right.
His kit also comes with a cartridge case that is either at or modified to specs that allow you check the head space with it. Also useing the case in each chamber allows his range rod to make a finer measurement.

As far as I know Iowegan discontinued manufacture of these most excellent rods a couple years ago when the metal prices when through the roof. So far I've managed to acquire one in .45 and .357.

Back to my Ruger. The BM base pin was put in before I left Phoenix 11 years ago. I'd fired a couple thousand rounds through it with nothing odd to report other than the normal undersized throats. At some point I bought a BM base pin, just the regular one with out the locking screw. I put it in and shot something around 3,000+ rounds through it. Over a period of time I noticed a definite out of alignment wear pattern develop that I had not seen before.
At some point there were many threads here about cylinder alignment, Iowegan's range rods, forcing cones and what to do about them. I contacted Iowegan and discussed my Ruger with him. I even sent him some pics of the gun and his consensus was an out of alignment condition caused by the tolerances stacking up. So I borrowed a forcing cone reaming tool and bought one of Iowegans range rods and tested things.
As I said above, with the BM base pin the base pin tool catches on the bottom of the cylinder indicating it sat too high. Put the factory base pin back in and the problem was not there.
Here is a thread on Handloads.com that has a before and after pic of my Ruger's forcing cone:
http://forums.handloads.com/forum_posts ... 747&KW=460

So that's the story again.

Joe
 
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