08 February 2011

1000-yard Underhammer

“Hi. I had a look at your blog and saw a lot of underhammer rifles, so I decide to build one for long-range target use.”

So began an e-mail that I recently received from a reader in Canada. I like that simple, straight forward, pragmatic approach – I needed one so, I decided to make one. Most people would start by looking for a rifle to buy, not by building their own from scratch - which is unfortunate.

Sometimes we let our fears take charge of our lives and consequently we miss out on a lot of opportunities and satisfaction. Not to play the schrynque here, but it’s true that many shooters who would love to have an underhammer rifle are just afraid to jump in and make one of their own.They believe they can't do it.

Well, friends, one thing that history has shown us clearly is that making underhammer rifles is not rocket science and most of you who want one are waaaay more qualified to build one than you might think. Aside from the barrel which is a Green Mountain offering, the rest of the rifle featured here was made with nothing more than a hacksaw, rasps and files, sandpaper, and a small drill press. No, I’m not kidding.

It was built in two months of winter down time by Patrick Chevalier. He said that he chose the underhammer action for its fast lock time, clean view of the sights, and the fact that it would not spit cap fragments into his face. He shoots 60 rounds a day in competition and says that he feels a lot safer with the nipple on the bottom of the barrel.

Clicking on any of the photos will enlarge them for detailed viewing.
Clicking the Back button will return you to the text.

Patrick said that he fabricated the action from steel plate. I was rather curious how he whittled a receiver from a steel plate and when I asked how he did it he said that he used the drill press to drill many holes to remove as much steel as possible. Then he filed the rest of the piece to shape and polished with various grades of sandpaper.

That was pretty much the same method for making the buttstock and forearm. Drill away the bulk of what doesn’t look like a rifle stock and then rasp and file the remains into submission. He explained that he needed a high comb stock for shooting at 800, 900, and 1000 yards. The high comb and rather slow pistol grip work well for Patrick’s Creedmore-style prone shooting positions.

From this seemingly crude methodology emerged a very sleek, accurate, and beautiful rifle.

While Patrick’s fabrication methods may seem simple, his basic mechanical design was sound. To achieve the best accuracy, assuming that you have a first-quality barrel, you need a rifle that is stiff and solid. To attain that stiffness it is important that the barrel and receiver be united as tightly as possible.

Toward that end, Patrick connected the barrel and receiver with a single ¾” X 16 TPI (threads per inch) breechplug that was screwed and seated into the barrel tightly; then he screwed the barrel into the receiver and torqued the two together. Then, perfect bedding of the receiver into the buttstock resulted in a very stiff rifle. BTW, Patrick also included a 5/8” deep Nock-type chamber in his breechplug for better ignition and cleaner burning of the charge.

Chevalier shoots 400-grain .40 calibre bullets ahead of 80 grains of FFg blackpowder.

A tapered .40 calibre Green Mountain barrel was chosen for the project. Being 1 1/8” at the breech and 1-inch at the muzzle and 32 inches long provides the balance and accuracy that Patrick required. Because the 1000-yard game requires long heavy bullets to win, a 1:16 inch twist was chosen to stabilize the 400-grain bullets on which this rifle feeds. Eighty grains of FFg seems to be the magic load that provides the perfect velocity to stabilize those long bullets with that really quick twist.

The mainspring/triggerguard of the Chevalier action slides along the 
bottom of the hammer when it is cocked. The leather hammer fob makes cocking
the rifle very easy especially from the strained Creedmore shooting position.

Patrick’s action is very simple; the hammer and trigger are tightly fitted into a separate lower tang and the trigger is also equipped with a sear engagement screw. Although the hammer does not have a half-cock notch, Patrick devised a simple sliding bar safety that consists of a bar which slides in a track that is inlet into the forearm. Sliding the bar to the rear blocks the hammer from reaching the cap.

 A simple sliding-bar safety was devised which blocks the hammer travel.

Both the hammer and trigger were cut from steel plate and the hammer was then fitted with a brass hammer “head” which was soldered onto the hammer body. The hammer head is also cupped to help contain the cap flash and fragments which is the curse of #11 caps.

In addition to all the other interesting features of Patrick’s rifle, the rear sight is a Goodwyn-pattern as used on the Whitworth rifle in the late 1860s. According to Patrick the Goodwyn sight, as made by Ron Snover of Pennsylvania, allows for extreme windage adjustments up to 60 minutes left or right at 1400 yards. Patrick mentions that he has needed up to 48 minutes of windage adjustment at 800 yards when the wind was really blowing! He also made that nifty little sunbonnet for the eyecup.

Initially he mounted the sight on the top of the tang, but later inset it into the top tang for a cleaner appearance, which was a good call on his part as the resulting lines are indeed clean.

All in all the Chevalier is a very good design for a special-purpose rifle. Sometimes specialty rifles get morphed into forms that become unpleasing to the eye in order to satisfy the demands of function. But in this case, Patrick was able to balance form and function and honor the gods of aesthetics while pleasing the gods of mechanics with his clean lines and good craftsmanship.

Thanks, Patrick, for sharing your splendid rifle with us.

All photo copyrights claimed by Patrick Chevalier


leakypan said...

Beautiful rifle. I really like your sliding bar safety. I would like to ask Roger what he considers to be the best type of safe underhammer, either the half cock or a hammer block safety? I know that almost all percussion type firearms in the past had a half cock, but the hammer block safety (assuming the safety is applied) provides additional protection in the event that the hammer becomes cocked. Your opinion please.


Roger Renner said...

Hi Leakypan. Thanks for your feedback.

As for the best type of safety, whether hammer block or half-cock, would depend upon the use of the rifle.

In my opinion, the sliding bar safety is great for a target rifle in which the safety in engaged for only a short period of time. I believe that it's not a good idea to leave a hammer at full cock for any great period of time as it is stressing the sear surface of the trigger and can result in chipping the critical sear edges on the trigger and the hammer notch as they work harden even more, sometimes to the point of brittleness, from use and stress.

The half-cock notch has always been the preferred method of safety on hunting rifles with a hammer for that very reason. The hunting rifle is usually carried for long periods of time with the action in one of the cocked positions.

However, when the sear and half-cock notch are properly designed, there is no stress on the sear face or sear edges no matter how stout the hammer spring or how long the action is left at half cock.

Earlier I posted a graphic depicting the hammer/trigger relation that provides that optimum condition. Check back through the earlier posts and take a look at it.

Hope that's helpful.



Engineer said...

A very nicey designed rifle. I like the rear sight the way it has been set into the tang. There is one thing I need to know. Why is the hammer face made up in brass and what are the advantages if any? I would also like to see a 1000 yard target after being shot at with this rifle.


Anonymous said...

I'm still wondering what the word "schrynque" means?

Roger Renner said...

As to the meaning of "shcrynque"...

That is the title of one who would venture an opinion regarding psychological matters, but who is not licensed to do so, such as a professional psychologist or shrink.

It's an old joke that goes back to my days at Guns & Ammo magazine where most people there would dump their heavy stuff on me. So I served as the office "schrynque" because I was not licensed to be a real shrink.

Hope that helps. If not, give me a call and we can chat about whatever is bothering you.

Glad to see that someone is actually reading this stuff!

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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!