Copy of an original blunderbuss

[davec2]

I will need to proof this barrel before I go too far with the build. It is a 7 bore. It's made out of better material than the original (I'm fairly sure) and the bore is slightly smaller (i.e. thicker walls), so it should be fine. However, anyone know what a 7 bore proof charge should be ?


#@!! $#@* !!!! Just found the British Gun Barrel Proof Act of 1868.......here is an excerpt ......





For a 7 bore, look at the powder and projectile weights required for a first and second proof !!!!!! I want to proof the barrel but this looks more like I'm making a pipe bomb !!!

I found an old chart in a 1972 Dixie Gun Works catalog that had some Belgian service and proof charges. The service charge was 158 grains behind a 7 gage round ball but the proof charge was over 500 grains !!! I like the idea of perhaps 180 to 200 grains as the proof charge behind 3 oz of shot for the first proof. Less powder and a little more shot for the second. The barrel is only 12 inches long, so I really don't want to fill it half way with powder and then a load of shot ....I could be inadvertently testing that old black powder BS about "oh you can fill the whole barrel with powder and it would still be fine !"

 

[davec2]

I found an old chart in a 1972 Dixie Gun Works catalog that had some Belgian service and proof charges. The service charge was 158 grains behind a 7 gage round ball but the proof charge was over 500 grains !!! I like the idea of perhaps 180 to 200 grains as the proof charge behind 3 oz of shot for the first proof. Less powder and a little more shot for the second. The barrel is only 12 inches long, so I really don't want to fill it half way with powder and then a load of shot ....I could be inadvertently testing that old black powder BS about "oh you can fill the whole barrel with powder and it would still be fine !"

Just for fun I put 600 grains of FFg in the bore. It filled the 7 bore (0.875 in this case) between the two blue tape marks....i.e. the brass showing between the two pieces of tape is the length of the bore filled with 600 grains of powder. Looks a little excessive to me.....but what do I know ???

 

[jstroke]

This is just fantastic! Looking forward to the proofing results.

 

[davec2]

This is just fantastic! Looking forward to the proofing results.

I’ll post a video Should be fun

 

[jstroke]

I’ll post a video Should be fun

I was hoping you’d say that!

 

[Pete G]

I don’t like exposing a gun to excessively high pressures just to see if it will fail. A double load seems to be adequate.

 

[davec2]

Pete,

I agree with you.

 

[Brokennock]

Just for fun I put 600 grains of FFg in the bore. It filled the 7 bore (0.875 in this case) between the two blue tape marks....i.e. the brass showing between the two pieces of tape is the length of the bore filled with 600 grains of powder. Looks a little excessive to me.....but what do I know ???

I would think it would be spitting shot and powder out the muzzle before the entire charge gas burned, just based on proximity of the front of the charge to the muzzle...
But, I'm probably wrong and someone will be along shortly to tell me so and, hopefully, why.

 

[PathfinderNC]

Dave- Pleaseeee be careful and use a very long fuse

(Wait- don’t you test out rocket engines ? )

 

[davec2]

Pathfinder,
Yes…..I test rocket engines for a living…. So I will fire this barrel electrically from a safe distance….

Brokennock,
I think you are correct that a lot of the powder charge would burn in the air outside of the barrel. We will see.