Smith carbine flash channel screw length?

[Kevin Tinny]

Hello:

I have what was an unfired, Second Model Smith carbine #10,554.

It is 100% original and unaltered. Close inspection viewing through the bolster nipple cavity shows that the "clean-out" (sorry Lou) screw extends two full threads into the round flash opening. The carbine fires perfectly and very accurately, with never any issues for approximately 400 shots to date.

Is this screw length and thread protrusion normal in an original, please?
With all the craftsmanship that the "Chicopee complex" put into Smiths, there must have been a reason, if anyone now can share that, too, please? Thanks.

Kevin Tinny

[hawkeye2]

I believe that Kevin is saying his screw is 2 threads longer than it needs to be and not just 2 threads long. As long as it functions as it should the extra threads aren't an issue. The only problem you might encounter is fi the exposed threads rust and you go to remove the screw. The corroded threads could damage the female threads as you remove the screw. I would be tempted to replace the screw with one of the exact length, bag & label the original to go with the gun for a collector.

[Kevin Tinny]

Thanks, guys:

Yes, two threads longer than needs be. If those two were not there, the end of the screw would be just at the edge of the hole.

Is this normal on an original, please?
Won't cut it. Has to be that way for a reason.

Tx again,
Kevin Tinny

[Muley Gil]

"
Six lands and grooves..."

It better be one groove, turned in a spiral. :D

[Hal]

"Pitches" might be the term you are looking for.

[John Bly]

I just repaired a Pietta Smith carbine in which the cleanout screw blew out. The screw only had about 1 thread holding it. It was destined to fail. The nipple hole had been drilled about .700" deep leaving no material on the side of the bolster for the screw to engage with. I tapped the hole to depth with a bottom tap. I screwed a 5/16-24 bolt into the hole and measured the depth it was engaged. I removed it and cut it to a length for a proper nipple fit. I loctited it in place and redrilled the flash hole and connecting hole down from the nipple. I tapped the end of the flash channel 10-32 and made a new screw with the length just to sit flush with the hole down from the nipple. The threads for the new screw are almost entirely in the insert. It is now safe to shoot.

I don't know how many of these are out there like this but they are all destined to blow out the screw. One thread is just not enough engagement for any sized screw to hold up to repeated usage.

[Randall]

Eggman, where did you get your replacement clean out screw?

Thanks

[singleshot]

Not all that sure but they were probably made that way to help funnel the flame into the main channel. That would be my assumption as to why the screw extends into the main channel.
.






TE]

[singleshot]

Macmaster-Carr located in NJ carries a low profile slotted screw that can be purchased @ how ever many U want.

[bobanderson]

I've already been tossed off three N-SSA teams.


Maybe you should seek out a team without a social media connection.

[Kevin Tinny]

Hello:

Lots of interesting stuff here, but can anyone please tell me why there are three extra threads on the ORIGINAL screw in my original Smith that project well into the opening below the nipple and reduce its opening by roughly 50%?

Wondering why the factory would have done that.

Anyone else found the same thing, please?

Thanks,

Kevin Tinny

[Lou Lou Lou]

Kevin, to direct fire to the bouche
e

[Kevin Tinny]

Thanks, Eggman:

Another skirmisher has shared off-forum that he has observed the extra threads in unaltered originals.

Perhaps they deflect excess flash that would otherwise erode a depression that could hinder consistent ignition?

My ignition with the extra threads in place is fine with never a hang-fire or failure.

Guess my curiosity has devolved into how many angels can dance on the head of a pin.


Thanks,

Kevin Tinny

[Bruce Cobb 1723V]

Although rusty this picture shows an original Mass Arms hole. Notice the nipple recievers threads do not enter into the side screw cavity. The bottom is machined concave to extactly match the bottom of an original nipple. The side screw body does enter into the flash channel hole maybe a millimeter. Never looked at repros much, but think the theads in the recievers may go too deep?? Are the nipples used in them flat on the bottom or slightly rounded like originals?

[Kevin Tinny]

Thanks, Bruce:

Pictures are worth lots of words.

My original has both a rounded base on the nipple and a corresponding dished hole.
The original and repro b-copper nipples fit quite closely against the opposite surface with only tarnishing, not crusty fouling showing on the nipple.

My "screw" threads show the same form of projection into the flash channel just below the flash hole as in your photo, but mine is approximately 1/3 more so that one-half of the round hole is obstructed. The underside of the head of the screw bottoms against the shoulder in the hole and the screw head is neatly flush with the outside of the bolster. This tells me the screw fits correctly.

My take on this is that your photo's appear to confirm that this seemingly extra projection of threads is common on unaltered originals with original screws.

Again, I wonder IF this was intentional, perhaps to reduce erosion opposite the flash hole.

All the best. See you in Oct at the Nat'ls.

Kevin Tinny

[John Holland]

I think perhaps we are overthinking the whole thing! These arms were manufactured quickly to fill the expediency of arming troops in the field. Their life expectancy was some 18 months, or so. I really don't think applying modern manufacturing techniques and expected longevity are applicable!

[Bruce Cobb 1723V]

Materials and heat treatment back then were still in the dinosaur age. Lots of things got too soft or so hard they broke easily. We fire our firearms far more than they ever thought possible. And yes, things just wear out.