Problem with inletting manton pistol lock main spring.

[Rolf]

On all the practice stocks I've done so far, I haven't been able to inlet the main spring without breaking into the barrel channel. I'm using  12" straight octagonal GM barrels , width 15/16". .
Would it be possible to grind 1/16" - 3/32" off the top/short arm of the main spring, or will this ruin it?

Best regards

Rolfkt

[rich pierce]

Don't worry about it.
Also, you sure are getting a lot of practice shaping stocks!  Most of us do all our inletting into a rough blanks, get everything in order, then shape the stock.

[Longknife]

I have beveled the top arm before, grind slowly and quench often...Ed

[Bentflint]

Maybe your ramrod hole is too straight. try kicking it away from the lock.

Bruce Everhart

[smart dog]

Hi Rolfkt,
I would not worry too much about breaking into the barrel channel as long as the spring will clear the barrel. Even if you preserve the thin sliver of wood between the spring and barrel, the effect is only cosmetic because the strength is nil. I believe that problem is why many springs on English guns have a long lug that anchors into the lockplate bolster.  The long lug positions the top leaf of the mainspring low in the inlet rather than having it angle upward toward the bolster. It allows you to avoid breaking into the barrel channel even with a large barrel and small lock combination.

[D. Taylor Sapergia]

Great observations Dave - my sentiments, exactly.

[Dphariss]

This lock is too deep. It needs the tumbler, the bridal and parts of the mainspring reduced
so that less wood needs to be removed.

Grind or file the offending parts of the mainspring to allow more wood the be left in the lock mortise. Just maintain original or similar contours and remove no more than needed.
Part of gunsmithing is modifying parts to work as needed.

Dan

[smart dog]

Hi Taylor,
How is your hand?

dave

[jerrywh]

English gun makers went to great lengths to lighten their guns as Dpharris suggests. However, if a person is not experienced at heat treating steel and tempering springs and such along with forging skills you can get into real trouble. Most of us old guys like DanPharris , myself , Gusler and others had to learn that stuff because parts weren't available when we started. One should learn those things because it will enable you to make guns that most people are incapable of . Unique guns bring unbelievable prices, besides they are more fun to make and gunmaking doesn't  gets boring

[Dave B]

Rolf,
You can get some good effect from lowering you locks position slightly below mid line on the barrel. I have several original barrels and all the flint touch holes are not on dead center but are slightly below the line by at least 1/16th. This gives a little more clearance for the main spring and helps get a better angle to the lock panel inrelation to the breach tang wood transition. My English pistol barrels are this way(one sea service one dragoon) and one American has this design feature. Just a thought.

[Rolf]

Thank for your suggestions.
Most of you suggested, I ignore the break through into the barrel channel. Its a cosmetic flaw that won't be visible with the lock in place. Tempting solution.

Dave B, lowering the touch hole 1/16" might solve the problem. Please, could any of the other builders comment on the idea? Will this effect firing the pistol?

Dan, Jerry, I might be able to borrow a lathe and a mill. How much can I reduce the thickness of the tumbler, bridal and main spring?I gather the tumbler is reduced on the side without the fly.I have no experience with locks and I'll need some guidelines to follow, if I'm going to try this.

Bruce, the ramrod hole does not break into the lock mortise, so I don't think that's the problem.


It looks like the third stock is coming close to what I want. If all goes well, I'll make the butt cap based on it. I'll then reuse all the parts on the fourth and hopefully last practice stock. Then I start on the curly maple and make the final pistols. On the last practise stock, I followed these steps:
1. Inlet barrel into plank.
2. Cut out stock profile with bandsaw and router.
3. Carved ramrod channel + drilled ramrod hole.
4. Inlet lock
5. Bandsawed forestock to 1/8" and rasped away excess wood on panel sides. (blank still square)
6. Inlet thimbles, trigger, triggerplate and triggergard.
7. final shaping /carving of stock.


This is my first build. I've only seen pictures of muzzle loaders. Black powder shooters in the clubs around where I live in Norway use rolling block rifles or revolvers. I've read the three recommended books on gun building, but it's often first when I make mistakes on a practice stock, I understand the explanations. Nobody sells curly maple and muzzle loader parts in Norway and importing stuff is expensive. I'd rather learn making practice stocks, than waist good parts on a gun I'm not happy with.


Best regards
Rolfkt

[Hoot AL]

This is not complicated. You can use a bench grinder and a cup of water to quickly cool the spring in the process.

 You grind off the metal on the spring in the widest section lengthwise.  You can remove 10% of the width of the spring and have no effect on the performance of the spring.

The big problem you generally run into is having the spring dig into the ramrod channel if it is crooked. When drilling the ramrod channel it is best to drill toward the sidepanel and not the lock.

Got a question for you.  Are you using any power tools to remove the wood or are you doing this by hand?  If done slowly and properly, you will not be removing this amount of wood to expose the barrel channel.

Just curious.

Hoot Al

[keweenaw]

Rolf,

Here are a couple photos of an original Manton lock circa 1817.  You can see how low on the plate the mainspring is placed.  You should definitely file a bevel on the edge of the spring and considerably taper the upper arm in at the rear.  The tumbler isn't very thick on this lock but it didn't have a fly on it, I'm thinking it's no thicker than 0.180" - 4.5mm.  Having the bridle screws countersunk into the bridle also reduces thickness appreciably.

[Rolf]

Got a question for you.  Are you using any power tools to remove the wood or are you doing this by hand?  If done slowly and properly, you will not be removing this amount of wood to expose the barrel channel.

Just curious.

Hoot Al

I use a router to carve out the bottom and side flats of the barrel channel. I start by routing out the bottom flat the full depth of the barrel. Then I rout out the side flats. When I do this I set the router depth set 1/16" shallow of the full depth of  the side flats. The bottom diagonal flats I carve out by hand with gauges and scrapers.

Best regards
Rolfkt

[Long John]

Rolf,

This is a bit of an engineering issue.  

The working part of the spring is that part that extends from the tumbler to the pin that goes through the lock.  Most mainsprings are not designed to flex between the lockplate pin and where the spring is attached, either to the bolster or to the lock plate.  In many locks with cast springs the cross-section of the spring at the bend is so thick that there is essentially no flexure in that region at all.  The part of the mainspring that extends to the lock bolster or to the screw (depending on the lock design) only serves to prevent rotation of the spring about the pin that goes through the lock.   That pin is in shear!  What is the cross-section of the pin; perhaps 3.5 mm?  (1/8 inch for the rest of you)  The static arm of the spring does not have to be any stronger than the lock pin.  The static part of the spring, the part of the mainspring between the lock bolster and the pin that goes through the lock, can be thinned down with no adverse effect on gun performance as long as you don't upset the heat treating.  Don't use a bench grinder - use a hand file and take nice smooth strokes along the length of the static arm of the spring.  I have thinned down the static arm of the mainspring on every rifle I have ever built (12 and counting) with 5 minutes of file work while the spring is in a padded vise.  Just taper the spring from the plate pin to the boss or bolster pin, whichever, as much as you need to achieve the fit you want.

And by the way, that lock mortice will NOT be always covered up!  When the shooter is done shooting for the day she/he must remove the lock to clean the pistol.  That is when she/he sees whether the gun was put together by some one who takes pride in his craft or not.

Best Regards,

John Cholin

[Rolf]

Snyder,
Thanks for the lock pictures and info. Very interesting. The short arm on my main spring tapers from 0.38" to 0.35". Do you think I can increase the taper to 0.29"?

When I'm finished with these pistols, my next project will be a pair of English style duellers. I've been working on plans for the set trigger you posted pictures of. I hope to use it on the duellers. I've got hold of some Plexiglas and plan to use it for a "see through" mock up of the trigger. At the moment the set trigger project is put on ice. I got to finish my Kentucky pistols. One of the guys at my shooting club has placed an order for my last practice stock + parts (barrel and lock not included) and paid for it with 2 Ed Rayl swamped barrels.

Best regards

Rolfkt

[Rolf]

Thanks for your answer John. The short arm of the spring is 0.37" at the lock pin and tapers to 0.35" at the bolstster. The lock pin is 0.1" thick. If  understand you correctly, I can file the taper down to 0.2" at the bolster. If I do that, I should be able to clear the barrel channel.

Best regards

Rolfkt

[keweenaw]

Rolf,

You need not do that as a straight taper.  The upper arm on those springs starts in at a straight taper and then has a radius on it toward the end with the entire top edge beveled.

Tom

[keweenaw]

Rolf,

Here's something else to consider on your lock inletting.  You are removing wood you shouldn't remove.  You should be leaving a bridge of wood between the front of the lock that goes under the bolster to the rear portion.  This piece of wood helps prevent any flash that goes between the barrel and the bolster from getting down into the guts of the lock.  The photo show's a lock mortise I rebuild on an original early 19th century rifle that had been refit with a Manton lock that didn't fit the mortise.  The new wood I put in is fairly obvious, including the piece I'm talking about.



Tom