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Discussion Starter #1
I went to the range last night and was trying some new Penn 95gr SWC bullets in my Single Six .32 magnum. I bought this troublesome piece at a gun show last year and have been toying with it ever since. I discovered early on that the cylinder was out of alignment with the bore as well as having chamber throats that measured .311 inch while the groove diameter was .313. First I sent it off to cylindersmith.com to have the throats opened to .314.

I ordered a Power Custom oversized cylinder latch from Brownells and installed that which made a huge improvement to the alignment but not perfect. Then I used Iowegan's method of putting a washer on the trigger pin and that got it almost perfect.

Group sizes with most loads tested still were not great, 2 to 3 inch range. Remember I am spoiled by my .41 magnum BH which will hold ten shot groups in 1.5" at 25 yards.

So while shooting the new Penn bullet loads I decided to try something. I put on my left glove and with light downward thumb pressure on the left side of the cylinder I let the trigger go on five rounds. The first time I did this I put five shots in 1 1/8". The first five of this load without the pressure was about 2". Then I shot another load without thumb pressure and put five shots in 2.5". With pressure another five went into an inch. This was all done at 20 yards since this gun is a Vaquero style with tiny sights.

Now here is a question for Iowegan. Should I take a few thousandths off of the lower tooth of the pawl to relieve some of its "push" on the cylinder?
 

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shdwrdr, No! The pawl is directly linked to the hammer so when the hammer starts forward, the pawl is retracted and no longer contacts the ratchet. The pawl has absolutely nothing to do with cylinder position when the gun is fired. The only thing holding the cylinder in position is the cylinder latch.

When you install shims on the trigger pivot pin, the hammer should be down because that's where it will be when the gun shoots. The photo shows a shim placed between the trigger and cylinder latch. I suspect you used a washer that was too thick and is not letting the cylinder position itself when fired.

The forcing cone is designed to accommodate slight cylinder-to-bore misalignment. I would take a look at it to make sure the cone is smooth and a good transition from mouth to lands.

Another thing related to the c-t-b alignment is the base pin. The cylinder latch controls horizontal alignment and the base pin controls vertical alignment. Using an after market base pin such as a Belt Mountain, will lift the cylinder a few thousandths. Sometimes an oversized base pin improves accuracy (better c-t-b alignment), sometime it makes alignment (and accuracy) worse. If you have a Belt Mountain Base Pin in your gun, exchange it with a standard Ruger part. If you have the Ruger part, try a BMBP.

The only real way to determine proper c-t-b alignment is with a Range Rod. By positioning the gun as in the photo then having a range rod holding alignment between the cylinder and bore, you can test to see where and how much your c-t-b alignment is off. Without that info, your are literally "shooting in the dark".

 

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Discussion Starter #7
I received the base pin and also a second one for my 50th Anniversary model. That pin wouldn't fit. Then it occured to me that the 50th Ann. model has a smaller frame and thicker barrel than NMs. So I called Belt Mt. directly and ordered the correct pin. Then I took the New Model pin and put it in my OMSBH. Even with the spring loaded plunger is works.

So when the new pin gets here, hopefully today I will then have three new Belt Mt. base pins. All guns currently have loaded ammo ready for testing; the .357 and .44 are using Leadheads Keith bullets.
 

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Discussion Starter #8
Iowegan thanks for suggesting the base pin. I put the locking Belt Mt. pin in and not only did groups improve but most are now to POA. Before most were low and left. With fixed sights on this gun I am quite pleased with the results. All shooting was done at 20 yards.

The two groups on the right are with 3.8gr Unique (top) and 4.2gr (bottom). The two on the left are with 9.0gr each of 2400 and IMR4227. All loads are with Penn 95gr SWC at .313. I didn't have my chrono with me so don't have velocities.
 
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