Underhammer action conversion to tapered pins?

Well, dear readers, it seems that I may have kicked a hornets' nest with my comments about using Allen screws to retain the barrels in some underhammer actions as I've already received a few e-mails and Comments regarding the opinion I expressed in the earlier Underhammer Action Round-up. One e-mail comment was apathetic and the writer didn't seem to care one way or the other, but there were a few criticisms from some who defended the Allen screws. Most who took the time to comment, however, agreed that they, too, did not like Allen screws (or Phillips screws for that matter) on old timey guns from an aesthetic point of view and one mechanical engineer didn't like it from a more left-brain, mechanical-logic point of view. You can check the Comments on the earlier posts for more of the story.

A couple of our readers asked about the feasibility of converting an existing Allen screw action to other methods of marriage of barrel and receiver, including the more traditional tapered pin method. While I tried to respond to our reader, Sandman, in the Comment section in which he posed his inquiry, Google insisted that my comment was too long for the Comment forum. Not wanting our reader to feel I was ignoring him, too, and because there seems to be some interest in this subject, I've included my comment to Sandman, below.

In case you don't read the Comments that our readers post, (BTW, lots of additional information back there) Sandman was asking about using a stainless steel tapered pin that would be less likely to become corroded in the pin hole as was alleged as being a real bug-a-boo about using tapered pins to secure the barrel and receiver in a muzzleloader.

Hold on to your knickers, 'cause here we go, again...

Hello Sandman,

Thanks for your feedback. It's good to know if/that all this blogging is actually worth the time and trouble I put into it.

As for your question regarding the tapered pin, the answer is, Yes, a stainless pin would reduce the possibility of corrosion freezing the pin in the action. But, so will a casehardened carbon steel pin - if you learn to take reasonable care of your gun.

However, if you let your firearm go the point where a pin becomes corroded into the action, you have much greater problems than a mere sticky pin. I'd be more concerned about the rest of your lockwork and whether it's still in safe operating condition. But, that's just my opinion.

Getting back to the pin...

Your gunsmith can purchase both the Tapered Pin Reamer and the correct Stainless Tapered Pin from MSC Industrial Supply. In my opinion they are the premier supplier for all your machine tool/work needs. If they don't have it, or can't get it, chances are that it doesn't exist, anyway.

You can view their virtual catalog at: http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1702339&PMT4NO=80252690.  If the link doesn't work, just copy and paste it into your browser and you should be okay. (If you're a machine head you may wish to order their hard catalog with your order. It's a valuable resource.)

Actually, that URL will/should take you directly to the page where you will find tapered pin reamers.

A good-quality, high-speed steel  #4 tapered reamer is item: MSC #: 02401032 which is just about perfect for your size application. Cost is a mere $14.89 each. No need to break your piggy bank.

The #4 Stainless Tapered Pin is item: MSC #: 67701763. The pin is 1 1/2 inches long, which gives you plenty of length for the width of the action you are working with, and the cost is only .99 cents each. At that price you can afford to have a few spares on hand.

The following link will take you directly to the tapered pin section of their virtual catalog: http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=2030482&PMT4NO=80254573. You may also wish to order a cup-faced punch to drive the tapered pin from the hole and re-install it so that it won't slip off the pin while driving it. Sorry, you'll have to look that one up yourself.

As a side note, one of the reasons I like MSC is that their technical staff is first class and is available to answer any questions you may have. Not only about the correct product for the problem at hand, but also the correct use of it. If your gunsmith has never installed a tapered pin, the guys, and gals, at MSC will walk him through the process so he can do it like a pro.

One aspect to consider in any firearms welding, and certainly in this process of conversion for installing the tapered pin in the U/H action you have, begins with choosing the right alloy for plug welding the existing screw holes. Most people would erroneously assume that you need a real hard alloy material to plug those holes.

NOT TRUE. Most U/H receivers are generally cast of mild or medium carbon steel. You should use a similar rod or wire to fill those holes. If you use a much harder filler material, you may experience flaws in your final metal finish as the harder filler material will generally not brown, blue, or case-color exactly like the surrounding material.

While tapered pins can seem tricky at first, installing them is not rocket surgery. If you drill and ream a few practice holes in some scrap material, you, or your gunsmith, will figure it out in short order. I'm assuming that your gunsmith knows what he's doing, or will learn - before taking on your job.

Again, removing and installing the pin is no big deal if you don't allow the pin to freeze in the hole - or you use a stainless pin. Like any other mechanical device, if you live in a climate that is very humid, you should more frequently inspect your rifle for corrosion and clean as needed. That would include occasionally removing the tapered pin and checking the barrel/receiver union for rust if you don't normally take down the rifle for storage after returning from the range or field.

If, by some slim chance, the pin does freeze in the hole, there is no need to massacre the pin and gun with heavy blows from an improper punch and a bigger hammer.  You simply give the pin a shot of penetrating oil, let it set for an hour or two, then try to drive it out. If it's still stubborn, then heat the pin with a propane torch until the oozing oil starts to bubble and smoke. Then drive the pin out. It's that simple.

BTW, be sure to clean all the corrosion and oil out of the corroded hole before installing a NEW stainless, tapered pin to replace the old one.

For those who are not overly concerned about swapping barrels and take-down capabilities as provided by either Allen screws or tapered pins, there is another method of securing the barrel to those actions which offer Allen screws. The other method involves plug welding the screw holes, dressing the holes, and then silver soldering the breechplug into the receiver for a super-secure attachment. Then the barrel is simply screwed onto the breechplug and torqued up tight. That does require a bit of fitting, yes, but, again, it ain't rocket science and is worth the extra effort if you appreciate a clean look and an extremely sturdy rifle.

Hope that's helpful.

Cheers!

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