Cap burn through on a Smith

[threepdr]

I bought a very used Smith Carbine recently and had B. Hoyt reline the barrel for me. He did a great job and the turn around time was only about 3 weeks. :D

I shot it for the first time this AM and it groups nicely. No ingition problems at all, however the flash burns through the cap on each shot. Each used cap has a 1/16 inch hole burned through the top. I've never seen this on any gun before. It also deposits an unusual amount of crud around the nipple and bolster.

Is this common. Time for a new nipple? Any pressure issues to be worried about here?

Thansk

[shilohzowie]

Beleive it's time for a new nipple. However what does the flash hole look like?

[Ken Hansgen, 11094]

Sounds to me like too mush pressure, altho' I'd also look at replacing the nipple if that's enlarged. What's your load, anyway? Is the bullet sized too large for the barrel?

[shilohzowie]

Is your mainspring weak?

[threepdr]

The mainspring, although not heavy, pops the cap just fine and does not move due to venting through the nipple.

The nipple is steel. The hole is not large, but much bigger than the pin hole as in an AMPCO nipple. Now that I look at it under a magnafier
the hole is an irregular oval shape.

I guess the nipple is burned out and needs to be replaced. Will an AMPCO with the tiny hole work OK on a Smith?

I was shooting two loads. Hoyt cut the barrel at .515. 1st was 30 grn FF behind a 350 grain bullet Rapine bullet that casts at about 3.18. (don't have a sizer yet). The second was 33 grns behind a Lee 450 grain that measures about .515.

For what it is worth, the Rapine bullet shot much better.

[Ken Hansgen, 11094]

Sounds like the problem is with your nipple (this is also the most common source of such troubles). All I can say is try the replacements you have--I found I got a number of misfires with some replacements--none with others. My Smith also has a Hoyt-relined barrel and I size to .517. So try getting a sizer. What means 3.18 anyway?

[threepdr]

oops...meant to type .518 not 3.18 :shock:

I'll look for a new nipple at the next shoot

[Dominic Infante, 8359V]

I do not think that you have a problem. No ignition problems and the carbine grouping nicely suggest it is working properly. The carbon that is blowing back to the nipple and the outside of the bolster area is also an indication that the nipple is correct because the alternative would be for that carbon to buildup below the nipple where it would eventually affect ignition. With buildup some of the heat from the flash is absorbed resulting in a cooler ignition and the bullet striking lower than normal. After shooting 50 plus shots the area in the bolster under the nipple should be relatively clean. The hole burnt in the cap probably is an indication that the cap metal is relatively thin. With thicker metal, the sides of the cap are blown upwards. Either eventuality allows for the proper carbon blow back.

In the early 1990s another team member and I began shooting Navy Arms Smith carbines at about the same time and we experimented extensively with nipple use and also bullets and loads. After trying several different nipple sizes we both concluded that the original nipple supplied by Navy Arms, which also is their replacement nipple, worked best in terms of accuracy and keeping the carbon buildup below the nipple to a minimun. The opening measures .075. Do not bother replacing the nipple until is burns out around 2 thousanths. The nipples with smaller holes simply did not work as well. With the proper nipple cleaning a Smith is so much easier than, for example, my Sharps. In fact, the Smith clean out screw may not really be necessary.

[FlinchJerk]

Folks.....I mostly shoot original percussion guns at NSSA, ones that have seen a lot of use during the wowah. In most cases the faces of the hammer recess that strike the cone have an irregular circle beat into it a bit from the hammer striking the cone. I assume that hammers were hardened, but were less hard than the cone, so the hammer face took the beating a bit more than the cone.

The result is many of the shot caps have a big hole in their tops as the hammer face strikes the cap and, like a cutting die, chops out an irregular disk of copper about the diameter of the cone. What result that phenomena may have on consistent accuracy is beyond me. On a rest, the original guns all shoot pretty tight. Offhand, on occaision I flinch one into a target......

Just to add to the information of the discussion topic....

Yours in the hobby.

Dean Nelson
1st MD Infantry, CSA, N-SSA

[P.Altland]

I have the exact same problem with caps burning through. I lent my Smith to a teammate at the Bedford and got concerned when he hit only a few targets. The gun had been very accurate using the Rapine 515365. After buying my Garrett I used the Smith as a backup or a spare for another team member. Took it to the range a couple weeks ago and found the accuracy was gone and the caps were burning through. I have always used the German caps and never had that problem till now. Gonna try a new stainless nipple.