16 February 2010

The Underhammer Action Round-up. Finally...

Welcome Ladies and Gentlemen to The Underhammer Society’s first Underhammer Action Round-up.

Since starting this blog, there have been numerous requests from builders all over the country – and even some requests from a few foreigners - for recommendations of a good quality underhammer action. It seems that those few who are making and offering underhammer actions are far and few between and remain virtually unknown by most underhammer aficionados.

In order to remedy this unfortunate situation I have contacted several underhammer builders to invite them to show off their wares for your consideration at our Underhammer Action Roundup.

However, before we begin, as the old saying goes, “I have some good news, and I have some bad news.” First, the bad news...

I am sorry to report that our friend Wade Ingrham is out of the running in this Round-up. Many will remember my report of some of Wade’s work in earlier posts on this blog. It seems that Wade (remember that he is 88 years old) is stuck in a wheelchair - for a bit, anyway - and is unable to get into his shop every day to tinker with his underhammer projects. While he’s determined, and threatens to get back at it, for now we must consider that his actions and rifles are not available. We extend our best wishes and hope for his speedy recovery.

Many of you have been waiting for this Round-up to learn more about the actions of Charles Bowers. We were hopeful that Charlie would be able to participate, but he said that he is recovering from an injury and that he, too, is unable to get back into his shop for the moment. However, as soon as he's able, he will again be providing his underhammer actions and you will find an announcement here when he’s back at it. Our best wishes for a speedy recovery to him as well.

That’s it for the bad news. The good news is that there is no more bad news - except, perhaps, if you want to consider that there was not a great response to the Round-up. We have only three actions to review; however, I wish to thank those makers who did respond for taking the time to do so.

For, probably a variety of reasons, some underhammer action makers did not respond to my offer to show off their goods. Some didn’t even bother to return my calls. Only one was able to provide an action for review. But we’ll do what we can to provide you with the best information possible.

Before buying an underhammer action for your next rifle, it is important to understand that not all underhammer actions are created equal. Some are better suited for target rifles while others are suitable for hunting rifles. Some are good for both and some are not very well suited for either.

It was the intention of this Roundup to be able to compare the actions and their various features to provide you, the reader, with useful information by which you could make an informed decision before laying out your hard earned cash.

In considering the following, your evaluative criteria should include consideration of mechanical design, quality of materials and workmanship, and the overall aesthetics of the action.

So let’s get this show started. Remember to click on the photos to see them in detail. Then click the Back button on your browser to return to the text.

We will review the makers alphabetically beginning with...

Allan Foundry Underhammer Action


Medium-sized two-piece action intended primarily for hunting rifles

Internal coiled springs for both hammer and trigger

Non-adjustable hunting trigger

Half-cock notch on hammer for safe carrying in the field

Cast of 1020 steel which allows bluing, browning, or color casehardening of the action

Receiver features an integral breechplug for superb strength and stiffness in the finished rifle. Action is available in two standard breechplug sizes, 5/8” X 18 TPI (threads per inch) and ¾” X 16 TPI and will accept barrels up to 1” diameter or across the flats. (See comment below about the appropriate barrel size.)

Utilizes a ¼ X 20 TPI stock bolt (not provided) which draws buttstock into engagement with the receiver. Customer must provide a bolt proper for customer’s buttstock design. Rear of receiver is mortised to receive the buttstock and the stock bolt screws into an extension of the receiver which provides greater strength to the wrist of the stock.

A forearm may be mounted flush with the front of the receiver to provide greater protection of the nipple and cap from the elements, yet the rifle will still qualify as an exposed ignition system.

Price: $225.00


Many of you may know of Pete Allan as a renowned target shooter while others may know him as a muzzleloading rifle designer and builder. Actually, he is both and the founder of Allan Foundry. Pete has recently put the finishing touches on an improved underhammer action that I believe to be one of the best available to the underhammer gun builder. I give it high marks for mechanical ingenuity, quality of materials and workmanship and its aesthetic appeal.

The sample that was sent for this evaluation exhibited machining of parts where needed for precision and reliability of function, while the exterior is left smooth “as cast.” Although it could be rust browned as is, a bit of stoning and polishing would be needed if the action is to be engraved or for finer finishes or color casehardening.

The action consists of two major components; an upper and lower receiver. The barrel is attached to the upper receiver while the hammer, trigger and coiled springs are housed in the lower. Two screws hold the two halves together; one that is visible and one blind screw that enters from the rear of the action. I especially appreciate that factor from an aesthetics point of view as it seems all the rage lately to provide a whole collection of ugly and inappropriate screws on underhammer actions. BTW, the quarter in the photos is intended to provide a size comparison of the action. Nothing more.

I also applaud the design for incorporating a simple and unique half-cock feature for safe carrying afield. While Mr. Allan does not claim his action to be a target rifle action due to its simple and un-adjustable trigger, I would have no problem shooting this action in a match. The trigger was light and crisp as received. I believe the trigger can be easily prepared for serious target work BY A QUALIFIED GUNSMITH.

While the Allan Underhammer Action is one of the most advanced designs submitted for this roundup, there are a few things that the gun builder should be aware of before planning a rifle based upon this action. Understand that they are not necessarily flaws, just things to keep in mind as you’re planning the build of your rifle.

While the “specs” indicate that the action can accommodate a barrel of 1-inch across the flats, the actual width of the action - at the top where the barrel will mate with the receiver - is just less than one inch, actually measuring at .960” across the action.

This is not a huge discrepancy, but one which you should be aware of because a barrel that is one inch across will protrude past the edges of the receiver. Not a lot, mind you, but just enough to be visually and physically annoying. Your hand and fingers will catch the sharp edge of the barrel unless it is dressed to match the receiver. Another solution could be to order a barrel that is 15/16” across at the breech, depending upon caliber. Not a real big deal, perhaps, but something to be aware of before ordering your barrel.

While the specs call out a 1 inch barrel, after some study of this action, I believe that an octagonal barrel up to 1 1/8" across the flats could be fitted to this action. With proper treatment of the overhang of the barrel, the result would be a great looking rifle with a "serious business" kind of vibe - perhaps like a Sharps buffalo rifle with the oversized barrel.

My other concern about this action is the openness of the front of the action. I believe this condition will become apparent after a bit of shooting as the design could channel cap residue and fragments (if you use #11 caps) right into the lockwork within the action. I can think of a simple fix for this situation (use musket caps) so I’m not overly concerned about it. But again, it is something to be aware of as a possibility as you plan your build with this action.

The Allan Underhammer action is now available from several sources, including:

Pecatonica River Long Rifle Supply 
Phone: 815-968-1995

Muzzleloader Builders Supply (you may have to call them about this product)
Phone: 877-397-3008

The Gun Works Muzzleloading Emporium
Phone: 541-741-4118

Dixon Muzzleloading 
Phone: 610-756-6271

Tip Curtis 
Phone: 615-654-4445

Fire & Iron Manufacturing “H&A” Action


Solid receiver of cast steel following Numrich Arms underhammer pattern

External mainspring which also serves as the triggerguard

Un-adjustable simple, single trigger system

Half-cock notch on hammer for safe carrying in the field or on the range

Receiver is cast of medium carbon steel allowing bluing, browning, or color casehardening of the action

Receiver accepts separate breechplug which is held by three Allen socket screws.

5/8” X 18 TPI breechplug and ¼” X 20 TPI stock bolt are included.

Price: $175.00


Way back in the middle of the last century (which now sounds like eons ago, doesn’t it?) there was a great resurgence of interest in muzzleloading arms. George Numrich of Numrich Arms believed that there was a market for a simple, inexpensive, beginner’s level muzzleloader which he could sell either as a kit (also the heyday of the basement gunsmyth which is not to be confused with a gunsmith) or a completed rifle for less than a C Note. That’s a hundred bucks to our younger readers.

George chose the underhammer concept for his new product. It seems that he took much of his inspiration from the early underhammer pistol makers. He combined the separate metal receiver ideas of Allen and Thurber, Anderson, and Bacon, with the ingenious triggerguard/mainspring designs of Cook, Jones, Pratt and other very early UH pistol makers as well as later rifle makers such as Billinghurst, Brockway, and Warner.

As good as those basic concepts were, they all had one glaring fault – they had no half-cock notch in the hammer - they were not safe to carry with a cap on the nipple. George designed a lockwork that did incorporate a secure half-cock notch and his underhammer action was born!

Because Numrich Arms had bought up the rights to the name of the defunct Hopkins & Allen manufacturing operation, George decided to use that “trademark” on his new underhammer creation. That mis-marriage of name and product has confused shooters ever since. The fact is that the original Hopkins & Allen company did not produce underhammer firearms. However, this is the action that comes to mind for many shooters when you say “underhammer.”

I believe that the safe underhammer lockwork was George’s greatest contribution to modern underhammer history and lead to our greater enjoyment of underhammer guns today. It was his humble “Hopkins & Allen” underhammer rifle, after all, that introduced countless thousands of shooters to our sport and served as inspiration to several of us in the pursuit of excellence.

Why the trip down memory lane? Well, to introduce you to a replicator of the classic. Fire & Iron Manufacturing of Webster, Florida offers their version of George’s “Hopkins & Allen” underhammer action. While Fire & Iron has made some modifications to the receiver, employing an improved solid steel receiver, the lockwork is still true to the original design as devised by George Numrich over 50 years ago.

Fire & Iron’s H&A is supplied with a 5/8 X 18 TPI breechplug which is secured into the receiver by three ¼” Allen socket screws. Personally, I would like to see them offer this action with an optional tapered pin for securing the barrel to the receiver. A tapered pin has traditionally been used in muzzleloader gunmaking to allow for the quick takedown of the rifle or for swapping barrels. The tapered pin would also be truer to the original Numrich design as that was the way George did it.

(Call me picky, but I simply detest exposed Allen screws on a supposedly “antique” design. It’s akin to putting Jag wire wheels on a Model T restoration – it just ain't right. But, that's just me.)

The steel receiver will easily accommodate barrels up to 1 1/8” across the flats and with a bit of fitting of the nipple and slight trimming of the nipple cup on the hammer, even a beefy barrel of 1¼” can be attached.

The rear of the action has a mortise into which the wrist of the buttstock is fitted and the stock is then attached via a ¼” X 20 TPI drawbolt which screws into an extension from within that mortise. I like that feature as it provides more support of the stock at this otherwise weak junction. The drawbolt is included with the kit.

The cast steel receiver will require clean-up and polishing and will accept rust brown, hot blue, or case-coloring to finish. Or, you could just leave it polished in the white and let it acquire its own patination over time. That variegated and soft natural brown is a great finish if you’re going after that genuine old-timey look.

The hammer and trigger have been heat-treated and tempered and should probably be polished and left “natural” or they could be browned. Do not attempt to heat blue them unless you are very familiar with the properties of steel and understand the process well.

The trigger guard of this H&A action also works double duty as the mainspring and is attached to the receiver by - another Allen screw.

Recently, Mark Kisenwether, the owner of Fire & Iron Manufacturing, has been putting the finishing touches on another variant of his basic H&A action. This new offering is rather unusual in that its modification allows for the ease of swapping the buttstock. That’s right, the buttstock.

Photo 1. above, displays the right side of the Modified H&A receiver and the collar which forms the transition between the larger-wrist stock and the receiver. Photo 2. displays not only the left side, but also the the buttstock with the stock bolt installed. In photo 3. the pin which serves to keep the collar and buttstock in alignment with the receiver is clearly visible.

Mark designed a collar that fits on the back of the modified receiver and which is larger than the receiver itself. The collar’s larger diameter of 1 3/8” allows the builder to make a buttstock with a thicker wrist. A small pin is set into the rear face of the receiver which acts to keep the collar and the buttstock in proper alignment with the receiver. The rear of the collar is relieved to receive the wrist of the buttstock to provide a more secure ball-and-socket fit of the two components.

This new design also utilizes an 8½” long threaded rod that does not go completely through the stock like a drawbolt. It's intended to be threaded into a blind hole in the front of the buttstock along with a special adhesive designed to bond to both the steel and wood. The rod passes completely through the wrist and into the solid body of the stock. The smooth front end of the bolt protrudes from the buttstock and is then inserted into and secured to the receiver by two Allen screws on either side of the receiver.

Mark asked, What if you like a thicker wrist than the slender inch and a quarter diameter of the receiver? Or perhaps you prefer a pistol-gripped stock for bench shooting, or you may want another stock with a shorter length of pull for fall shooting when you would wear heavier clothing. Whatever the reason, now you can quickly and easily change stocks to match your shooting activities.

In all other respects Mark's modified action is identical to his standard H&A action.

Modified H&A  Price: $240.00

Contact: Fire & Iron Manufacturing:

Muzzleloader Builder’s Supply Billinghurst Action (kit)


Billinghurst-style of receiver cast of mild steel

External mainspring is investment cast steel and also serves as trigger guard

Simple single trigger that can be adapted to include sear engagement adjustment screw

Hammer does not feature a half-cock notch

Cast of low-carbon steel which allows bluing, browning, or color casehardening of the action

Breechplug, screws and pins needed to finish the action are not included in the kit

Kit cost: $89.00 (when available)


Some of the most famous and accurate of all underhammer rifle designs are those of William Billinghurst. In his day he built a variety of underhammer target rifles which incorporated both internal as well as the more familiar external mainspring. In those which utilized an external mainspring, the spring also acts as the triggerguard. It is one of the most ingenious features lending to the overall simplicity of function and is exclusive to underhammer arms.

Muzzleloader Builder’s Supply, recently acquired by Ryan Roberts and now located in Aberdeen, Idaho, supplies a Billinghurst-inspired underhammer action KIT that could be the basis for a wonderful target rifle. I specify “target rifle” because this design does not provide a half cock notch for safely carrying the rifle in the field. If you think you really want to build a hunting rifle on this action, there is a means of safely carrying it in the field. One solution is found in an earlier post further down the page on this blog.

Another solution is displayed in the photos below of the custom rifle of Bob Alderman in which he and co-builder Loyde Moler crafted a sliding bar safety that is inletted into the rear of the forearm. All in all a clever remedy to the safety issue.

While the MBS action is rather large and designed to accommodate the heavy target barrels associated with bench rifles, it can wear a more slender barrel when the barrel is properly fitted with a tulip breech plug. (Coincidentally, I just happen to have a design for such.)

The breechplug hole in the receiver is just under ¾ of an inch. The breechplug can be secured with a tapered pin in the true Billinghurst manner, or the breechplug could also be silver soldered into the receiver to create a semi-integral plug. Such methods, when properly employed, can provide a stiff and secure union of barrel and receiver which is essential to accuracy in a target rifle.

The kit consists of the receiver casting, a trigger bar or lower tang, hammer, a simple, single trigger, and a cast mainspring/triggerguard. The kit requires some light machine work mostly in the form of drilling pin and screw holes. The screw holes must also be tapped with appropriate threads. In addition, a bit of filing and polishing will be needed to ready the action for final finishing. The mainspring casting also requires heat treatment in order to function as a spring. Instructions for that process are included.

Making a good spring from certified spring stock is a craft all its own. Making one from a casting can be very tricky at best and is probably one of the reasons that many distrust the triggerguard/mainspring concept. However, I am told that the process described in the instructions does produce a good, durable spring. If I were to build this action, I would also craft a spare from flat bar spring stock - just in case. Or, you could just buy a spare from MBS as all the action components are available separately, as well.

As can be seen in the photos, most of the hole locations are marked in the castings by dimples. However, drilling with a drill press is still recommended to be more assured that the holes are drilled 90 degrees from the center-line of the action. A slight deviation from that ideal could result in a binding hammer or trigger, or both. Again, instructions are included.

That’s the good news. The bad news is that MBS is presently out of stock of this product and is waiting on their foundry to deliver. Hence, unfortunately, a sample was not available for our review, but photos were.

(Update: I've received word that the Billinghurst action is now in stock and ready for delivery!)

While I have gotten some mixed information from some of our readers about the quality of this product in the past, after speaking with Mr. Roberts about this issue, he has stated that the quality issues have now been resolved.

For more information visit: http://muzzleloaderbuilderssupply.com. It may be necessary to use their on-site search engine to find the underhammer page, in which case, be sure to use the keyword “Underhammer.”

So there you have it, friends.

Well, thanks for stopping by - that concludes our Underhammer Action Round-up. Again I wish to thank Pete Allan, Mark Kisenwether, and Ryan Roberts for their participation and friendly cooperation in our Underhammer Action Round-up.

As new things develop, I’ll try to get them posted here for your edification so check back often. In fact, if you like this site and would like to be notified of new postings as they are published, you can subscribe by clicking on the Subscribe to: Posts (Atom) link at the bottom of this blog page.

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markkw said...

I like to clarify a few things about my actions. The choice of using socket hex head (Allen head) set screws was to achieve the primary goal of having actions that are versatile and user-friendly. The hex socket screws greatly reduce the likelihood of drive tool slippage and drive failures (stripping/peeling) while providing maximum versatility. I do offer clients the option of choosing slotted head set screws too but it is important to remember that socket-drives are not "new", their use dates back to at least the early 18th century. Master Russian gun builders are credited with inventing and using socket-drive fasteners on guns even prior Peter the Great's founding of the state-owned Tula weapons manufacturing facility in 1712.

I chose to forego the use of a tapered pin for barrel attachment at it has at times proven to be problematic. While the tapered pin is functional, lack of sufficient corrosion protection on the mating surfaces often leads to the pin rusting-fast to the breechplug and/or action making removal extremely difficult. The use of too-much oil or other corrosion inhibiting compound can lead to a "false bind" where the pin will unexpectedly drop-out and if this happens while hunting and the pin is lost, the gun becomes useless. Even when all goes "as planned" and the pin functions correctly, removing and re-installing it to change barrels requires the use of a hammer and punch which not only adds to the amount of equipment one needs to carry but also leads to action damage from punch slippage or not having a sufficiently padded support under the gun. The use of threaded set screws eliminates all of the hassles and problems associated with a tapered pin while minimizing the amount of tools required and making for quick and easy barrel or stock changes. The same 1/8" hex wrench used to change barrel or stock also fits the main spring trigger guard attachment screw, a place where a straight slot screw is difficult to remove/install. Thus, only two tools are required for my actions, a straight slot driver for the trigger & hammer screws and a 1/8" hex wrench (or the smaller straight slot driver if one chooses the slotted set screws).

I believe in providing my clients with the highest possible customer service and as such, if one wishes to have a tapered pin barrel attachment, I can provide such with the client option of having the top screw hole permanently or temporarily plugged as one may choose to use it for a sight attachment at a later time. I also offer the service of converting tapered pin actions to set screws.

The stock attachment bolt used on my new "Maultier" action (modified H&A style) serves the primary purpose of greatly increasing the wrist strength as the wrist is always the weakest link on any gun. The Maultier stock bolt is designed with threads intended to bend and compress the wood fibers on installation so as to retain strength rather than loosing strength with threads that cut the wood fibers. The special adhesive I use further increases strength by joining the metal and wood into a single monolithic unit. The secondary effect of the Maultier stock bolt not only allows for quick and easy stock changes but also allows the user the option of using any diameter or shape adapter ring or none at all so the slim-wrist look and feel can be maintained without giving up strength and durability.

My actions are also highly adaptable to almost any receiver/tang style sights including standard side-mount and top-mount low-profile peep, lollipop, ladder, cantilever and even optical (scopes).

I welcome all inquiries as I run a full service gun building and black powder gunsmith shop. I can supply anything from raw parts to complete custom built guns ready to shoot in addition to standard gunsmithing services such as repairs, customizing and refinishing on underhammers and sidelocks.


Mark Kisenwether
Fire & Iron Mfg.
10958 CR 738-H
Webster, FL 33597

Anonymous said...

Hi again. I left a comment the other day on your underhammer barrel maker article about screws holding in the barrel. You mentioned a tapered pin and I asked my gunsmith about it. He said that he could do it but he didn't know where to get the correct hole reamer and the pin to fit it. Do you have a source for the reamer?

I was reading Mark Kisenwethers comment about pins getting corroded in the action and was wondering if we can make a pin out of stainless steel so it won't corrode. My gunsmith thinks that would solve the problem. Would that work?

Thanks for all the information in the action round up. I think it was very informative.


Roger Renner said...

Just a quick note to answer an e-mail question regarding the quarter in the picture of the Allen Foundry Underhammer Action. The quarter was included to provide a size reference to the action. Nothing more.

Mark Kisenwether said...


Common sizes of standard American taper pins are available in stainless steel but you must first determine if the existing pin hole is standard or metric. If it is standard American, the pin & hole will have a taper of 0.250"±0.006"/12" If it is metric, the typical rate of taper is 1:50 (1mm/50mm) however, the lack of uniform standards means a metric taper can be anywhere from about 1:38 to 1:75, it is normally best to avoid the grief and true the hole for a standard American taper pin. Standard taper pin reamers are available from machine tool suppliers for around $65-$140 each depending on type and quality. If you desire, the pin holes in the action can be reamed straight and threaded for set screws.

Mark Kisenwether
Fire & Iron Mfg.

Anonymous said...

Dear Mr. Renner,

I have been following your blog for over a year now and I am really impressed with the information that you provide. I've learned more about underhammers here then any where else on the web.

I think this is a great service to us underhammer guys. Please keep up the good work.

As you say, Cheers!


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About Me

Roger Renner

Hi. I've been a student, admirer, and designer/builder of underhammer guns for over 30 years. In that span I've built over 200 semi-custom underhammers exploring the possibilities from the ordinary to the exotic. In 1996 I founded Pacific Rifle Company to explore the market's interest in a high-quality underhammer rifle. Thankfully, that interest was, and still is, there. I sold PRC in 2006 but continue to craft high-end underhammers as I am truly afflicted with underhammeritis - which can be contagious!