Month: October 2006

Turned cases

Posted by on October 22, 2006

Thanks to those who commented on my little posting about lathe turned cases. My buddy has just made a small batch of ten Martini cases. He necks them down in a single pass without annealing them first. He is of course aware that that is not a good technique but it is still in the early stages. The interesting point is that they can be necked in a single pass without any apparent problem. For proper production necking will be in two passes, annealed before first pass, and before and after second pass.At this stage there is considerable variance in neck wall thickness but that’s because no great effort at concentricity has been made. For dimensionally consistent cases some fairly decent jigs will need to be made.The cases made thus far are however so good as to prove the practicality of the method. John D pointed out that Martini cases are OK with the straight drilled interior volume as no more than that is needed for a practical powder charge. Brett N suggested that chamber inserts are a better idea and less work. Both points are taken. The objective however was more than just making cases for the Martini, it was another step in the development of the ability to make what is needed if it cannot be easily obtained otherwise. As my friend put it yesterday, ” We are getting closer to the position in which we can make just about anything.”[Originally posted to SATalkGuns -- Admin]

Lathe turned cases

Posted by on October 13, 2006

I might have mentioned before that I have a buddy who is very good at making things. He is also a collector and shooting enthusiast. Has half a dozen Martini Henrys. You will all know that modern Martini cases are lathe turned, at least all those I’ve seen are. They are usually turned from the solid with a straight hole drilled down the middle for the powder space, ie very thick walls because it is difficult to machine a cavity anything but straight.I have a case made by North Devon Firearm Service that was first machined straight on the outside, or maybe slightly tapered, and the neck formed by reducing in a series of dies, and annealed at every stage. The discolouration of annealing is visible. That makes a case with a full interior volume.My buddy has just done the same. Turned the case in exactly that way and made the dies for reducing the neck. The resulting case is a trifle rough as it is just an experiment at this stage. But it is good enough to shoot, and good enough that the dies just need a bit of smoothing to get them dead right. I have no doubt that with a bit of work he will make cases as good as the NDFS case which is beautifully made.This is the guy that makes such things as 50BP Express ammo by soldering a machined case head to tube body he has reduced to size also in dies he made.As he says, never say die, anything is possible.[Originally posted to SATalkGuns -- Admin]

Accuracy&neck sizing&reaming

Posted by on October 1, 2006

We all know that neck sizing only together with other measures like neck reaming contribute to rifle accuracy. The objective of both is to chamber the bullet so that it is both concentric and parallel with the bore. OK, that presupposes that the chamber and bore also meet those criteria which can’t be guaranteed, but there’s no choice but to assume they are, because they will be in a good rifle and to assume otherwise is not to do the job.The principle is that if the case is fire formed to the chamber and not sized after that, and that if the neck is reamed or outside turned with a Marquart or similar tool, concentricity will be achieved. That’s well and good for typical bottle neck cartridges, but what about straight wall cartridges ? In a maximum chamber the cartridge will be a loose fit and anything but concentric, and straight wall cases can’t be neck sized. Or can they ? How else does one get concentricity ? Or isn’t it important ? Is it sufficient to seat the bullet to engage the rifling or almost ? How is fine accuracy achieved with target 22RF rifles, the case being straight walled ?I’m asking for opinion, preferably experienced opinion, because I don’t have much experience of straight walled cartridges and I have the idea of building a rifle in 38 Special for short range use (50m).[Originally posted to SATalkGuns -- Admin]