Spencer sear adjustment screw..

[Gtbpappy]

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Hello folks! Just picked up my 1st Spencer. I noticed it has an "extra" screw as noted. I have seen these on a few others. When and who may have added these? Government? The fella I got it from said it was for adjusting the sear to make trigger pull lighter and more accurate? Anyone else know of this? Thank! Great site..   hope my picture shows up.. using iPad..

[El Supremo]

Incredible discovery:

Thanks for sharing.  Am blown away if this creates better trigger pull. Don't recall ever seeing this in a photo.  Nothing apparent in Marcot, either.

Any chance we could get a good photo of the inside of the lock showing how the opposite end of that screws works?

And, is there is a fly on the tumbler to prevent the sear from falling into the half-cock notch upon release?

Most impressed and appreciative.

Respectfully,
El Supremo/Kevin Tinny

[Gtbpappy]

Kevin, I was looking around, and found this article.. sounds like this is an old modification. Not sure how old this one was. I don't have the proper tools here to pull it apart without messing up the screws... I talked to a couple of people, and thought this would not harm the value..

http://www.nwtskirmisher.com/useful-locks.shtml

[El Supremo]

Hello and thanks, Gtb:

Have seen and applied some of the tweaks, including pegging tumblers, that are in that article.  The problem for me is that once the weight of pull is reduced to around 3 pounds, there may not be enough sustained trigger finger pressure on the sear.  This causes the sear tip to bump the half-cock area and eventually damage the sear tip.  Most lock makers solve this problem by adding a "fly" to the bridle.  Flies are in bridles on Sharps and some altered Spencers (sporters) for this reason.  A few of these sporters do not have set triggers.  Also, on most unaltered military locks, the angles between the sear and full-cock notch are deliberately arranged to "work against" each other and minutely cam the hammer backwards during release.  This adds to the weight of pull.

Sharps locks are almost identical to Spencers, but the hammer positioning facets on the bridles differ slightly and produce different hammer timing positions.  So, (at least SHILOH) SHARPS TUMBLERS WITH FLYS DO NOT interchange without some tricky alteration. I have tried to thin both the width and thickness of the sear spring portion of the mainspring, with limited success. Placing a shim or collar on the mainspring screw to reduce the sear leg's pressure caused the spring to tilt and the bridle to be cocked and rub heavily, even on bridles that were close fits in the lock plate hole.

There are published photos of the insides of Spencer locks showing a larger DIAMETER internal mainspring screw, perhaps to reduce the pressure of the sear spring portion of the mainspring. One is on page 43 of Marcot.  

I wonder if anyone here has seen the same screw on Sharps locks?  I have searched and found images of EARLY slant-breech percussion Sharps locks with a SEPARATE v-spring for the sear instead of the common mainspring with sear leg.

Anyway, I now know HOW to achieve a reliable, durable 3# pull via Shiloh - Sharps main spring which drops pull weight 3 - 4 pounds, sear notch stoning and the addition of a fly, but all these changes, but for the spring exchange, are complicated and require a track record skilled gunsmith.  

The external location of the extra screw seems to be opposite the sear and may rotate elliptically inside to change sear tip engagement.  That is why I suspect a fly SHOULD be in the tumbler.

So, if and when you might remove that lock, I would be delighted to know what you find. Surely it is there for a good reason and since there are at least a few examples, it must work.

Now if we could also learn who made the rifling MACHINERY that created progressive groove depth rifling in Spencers, another solved mystery could be attributed to CAS/SSS members. People that have dug into the Spencer archives, now heavily disorganized, have shared that they saw nothing related to the rifling machinery.

All the best,
El Supremo/Kevin Tinny

[LongWalker]

I wonder if anyone has seen the same extra screw on any original Sharps locks.

Twice, both times on carbines converted to cartridge. 

[El Supremo]

Thanks, Longwalker:
Is there any Sharps place that you can direct me to that might include expertise on that screw, please?  If something might be in Sellers' book, mine went with a 40-70 years back.  Thanks.
El Supremo/Kevin Tinny

[El Supremo]

Hello:

I PM'd Herbert a few days ago for his thought on the screw.
He responded today via PM and indicated that he expected the following to also show as a Forum comment:

"This is a new one for me.  I have not seen anything similar, have seen flys in Spencer locks on sporting rifles, but these were on set triggers."

Respectfully,
El Supremo/Kevin Tinny

[LongWalker]

Thanks, Longwalker:
Is there any Sharps place that you can direct me to that might include expertise on that screw, please?  If something might be in Sellers' book, mine went with a 40-70 years back.  Thanks.
El Supremo/Kevin Tinny

Sorry, I've never seen anything in print about the modification.  You might try searching through the posts over at the Shiloh forum, or various collector boards.