Need cylinder measurements for loading blocks!

WhistlerSWE · Mar 9, 2010

I shoot a lot of PPC.

This season I will shoot a 686, a 627 and a 629. My plan is to design a loading block for my speedloaders, where the block is drilled from both sides, with L-frame on one side and N-frame on the other side, with recesses for .38Spl inside the larger hole for the .44 cartridges.

A friend of mine has the necessary equipment to make this block for me, but he needs the measurements.

I'm not all that great with the caliper, so I'm wondering if any of you guys have them already?

What I need is the distance from the center pin in the cylinder to the center of the chamber. I need this for both L frame and N frame.

Also, how large should one make the holes? I don't want them to wiggle, but neither do I want them to get stuck. Should I take into account for different types of bullets? I shoot primarily LSWC.

Here is a crude sketch of the basic concept:

john traveler · Mar 9, 2010

I've made speedloader loading blocks like you've described.

The easiest thing to do to get the correct dimensions is to remove your cylinders, remove the extractors & center pins and use it to trace the hole locations. Do this on a piece of sheet metal or plexiglas and use it as a template for the holes. This will avoid the measuring, marking, and transfering of drill centers which will give some errors, and may make speedloader loading harder.

A 3/8" spade bit is a good choice for .38 Special/.357 Magnum. The case body diameter is a few thousandths over 0.375, and the 3/8" spade bit will cut that just fine. An even better choice is a Forstner bit, and that will also give you flat-bottomed holes with minimum pilot hole showing.

The .44 case size is a bit odd, so you may have to use a fractional size twist drill to get it.

WhistlerSWE · Mar 9, 2010

I'd rather not disassemble my cylinders, that's why I created this thread and wondered if anyone already had accurate measurements.

HEADKNOCKER · Mar 9, 2010

What about buying a few speedloaders that your gonna use & load them up with spent brass & use that to mark the wood block..
Could work!!
Gary/Hk

tomcatt51 · Mar 9, 2010

HEADKNOCKER said:
What about buying a few speedloaders that your gonna use & load them up with spent brass & use that to mark the wood block..
Could work!!
Gary/Hk

Maybe he has a friend with a CNC verticle mill?

N frame seems to be a 1.092" circle (centerline diameter). I don't have an L frame to measure.

WhistlerSWE · Mar 10, 2010

tomcatt51 said:
Maybe he has a friend with a CNC verticle mill?

Yes, that sounds like what my friend said. It was something about having to do a CAD drawing and then using it with CNC machines.

Thank you for the measurement.

H Richard · Mar 10, 2010

I believe they are commercially available. I've seen competitors using them. Try Safariland.

tomcatt51 · Mar 10, 2010

I'm amazed. None of our "experts" here can measure a cylinder?

WhistlerSWE · Mar 10, 2010

H Richard said:
I believe they are commercially available. I've seen competitors using them. Try Safariland.

Safariland have for K and L frame .38Spl.
None for N frame .38spl and none for N frame .44Spl/Mag.
And certainly no blocks combining both calibers in both frames!

I'm with tomcatt51 on this one.

Jellybean · Mar 10, 2010

I don't have the measurements, and don't need them. So I'll tell you how to get them yourself.

Using your caliper measure the diameters of the center pin and one of the chambers individually.

Next put a tight fitting fired case in one of the chambers and use the caliper to measure from the outside of the center pin to the outside of the fired case.

Take that measurement and subtract Half of the measurements from the center pin and chamber.

ex. If the center pin measured A,
and the chamber measured B,
And the distance from the outside of the center to the outside of the fired case measured C.

You would use the formula. C - A/2 - B/2 = your answer.

tomcatt51 · Mar 10, 2010

Good grief. Talk about doing it the hard way. I used my dial caliper and measured outside to outside on two opposing chambers, then inside to inside, added the two measurements and divided by 2. That will give you the chamber centerline circle diameter.

Jellybean · Mar 11, 2010

Very smart, did you PM the results to Whistler? Or are they a secret?

tomcatt51 · Mar 11, 2010

Jellybean said:
Very smart, did you PM the results to Whistler? Or are they a secret?

If you'd actually read this thread you'd know I posted them. Post #5. Just for the N frame as I don't have an L frame gun to measure. Why didn't you? Maybe post #8 applies?

Jellybean · Mar 11, 2010

My apologies tomcat, I didn't see that, nor did I see anyone offer an explanation of how he could do it himself.

As to post #8, I don't consider myself an expert, and have never claimed to be. If there were any real experts here I wouldn't waste my time trying help people with their questions.

Need cylinder measurements for loading blocks!

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