Bullet Size for Trapdoor

[mr.tickle]

I recently slugged the bore on my 1873 Trapdoor, it came out to .458. What size bullet do I use? .456, .458, .460? I was planning on shooting blackpowder cartridges.

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[browningautorifle]

Can you just bump your mold? That should give it a couple more. Have you thought about paper patch?

[mr.e moose]

You should be good with a .458 pure lead bullet it will bump up a bit when fired.

[mr.tickle]

I don't have a mold for it, it will also be my first time shooting/reloading black powder. So I am having to learn a lot about this type of reloading from scratch. I also will probably buying the bullets starting out. Is 20-1 ratio soft enough?

[mr.e moose]

It should be OK. Where are you located? If in Canada I could suggest a few places or send you some to try out. The big thing with shooting the Holy Black is to leave no air space between the powder and the base of the bullet. If you buy a hollow base bullet fill the HB with a beeswax and Crisco lube and have a .458 card between the bullet and your powder. The Paul Matthews books are great for a beginning BP shooter. With modern cases you wont be able to get 70 grains of black powder in. You can use drop tubes and compression plugs but the best I can get is around 65.

[browningautorifle]

The big thing with shooting the Holy Black is to leave no air space between the powder and the base of the bullet.

Excellent advise, an air space with Black can cause you to damage a rifle right now...

[mr.tickle]

It should be OK. Where are you located? If in Canada I could suggest a few places or send you some to try out. The big thing with shooting the Holy Black is to leave no air space between the powder and the base of the bullet. If you buy a hollow base bullet fill the HB with a beeswax and Crisco lube and have a .458 card between the bullet and your powder. The Paul Matthews books are great for a beginning BP shooter. With modern cases you wont be able to get 70 grains of black powder in. You can use drop tubes and compression plugs but the best I can get is around 65.

I appreciate the offer but unfortunately (perhaps fortunately this time of year), I am in Florida. I was planning on checking out Matthews books. Will flat based bullets be ok?

[mr.e moose]

Nothing wrong with flat base bullets. One of my favorites is a 405 grain.

[mr.tickle]

Let me ask another question. The gun closed on both a no-go and field gauge. Yet I was told it should be ok with black powder loads. Is that true? The gunsmith obviously did not want to put him inself into a legal conundrum.

[Patrick Chadwick]

I recently slugged the bore on my 1873 Trapdoor, it came out to .458. What size bullet do I use? .456, .458, .460? I was planning on shooting blackpowder cartridges.

I imagine that by 0.458" you mean the GROOVE diameter and not the BORE diameter.

The following tips apply ONLY to BPCRs loaded with BLACK POWDER. Sorry to shout, but IMHO to use nitro in an original Trapdoor is irresponsible. Read the reloading manuals - they contain plenty of warnings.

1) If you use pure lead, then a reasonably weighty bullet (>400 gn) will slug up to fill the rifling, even if it is slightly under bore size, as in minie rifles.
However, this is not much use to you, as an 0.450"-0.451" bullet will not be held by the case neck.

2) If you use a bullet that is larger than groove diameter, then it will merely create unnecessarily high pressure as the bullet must be swaged down to fit the rifling profile. So forget 0.460", unless it is necessary to achieve the "hard-push" fit - see 4).

3) The harder the bullet, the less it will bump up. So whereas a pure lead bullet will bump up successfully, even if slightly undersized - see 1) - a fairly hard lead tin alloy, say 1/15 tin, will need to be groove size.

4) In my experience, a 1/20 tin-lead alloy will allow the use of either .456 or .458", whichever you have available. Pick the bullet diameter that is a finger+thumb "hard-push" fit in a fired case. No kind of a crimp is required. It is enough that the bullet does not fall out of the case! This will enable you to get away with using cases that are not resized at all! They last and last and last...

5) Forget headspace gauges on a BPCR that is more than a century old. Made maybe 50 years before CIP and SAAMI standards were defined. BPCRs all used rimmed cases, and there seem to be enough serious shooters around who use, for instance, reformed 10.3x60R cases (with a very thin 1.05mm rim ) as replacements for unobtainable cases with thicker rims (the 45-xx and 50-xx families have 1.64mm). I.e. 0.023" excess headspace. But only for the first firing. After that, the case hase been fire-formed to fit the chamber, regardless of CIP, SAAMI, etc.

6) If you use the "hard-push" method, then you can also seat the bullets ever so slightly too far out, so that they touch the lands. When the block is closed it will push the case right into the chamber, so that you a) consistently have a bullet just touching the lands b) the base is hard up against the block face. I.e. no "headspace" problem - real or imagined.

Hope this helps - it works for me.