Posted: 12/10/2008 1:44:03 PM EDT
 
Not very acurate but shoots.This is a stock barrel with nothing done to it. |
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Quoted:
It is missing rifling half way around barrel.Thge other half comes to edge. What I think you mean is that you see rifling touching the sharp edge of the chamber at the bottom and the rifling starts perhaps 1/8" forward of the chamber at the top of the barrel. Is this so? Can you take a pic of the bottom of the chamber as well, just like the first pic? It could be an undersized or misaligned chamber reamer, if I understand correctly. |
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Yup, looked at the second pic.
I am no expert, but that is a screwed up chambering job. No wonder it does not shoot worth a tinker's damn. What size groups does it shoot? I wonder if the manufacturer says it is "in spec?" I would guess a severely misaligned reamer or a very undersize chambering reamer button. |
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IMO, the top pic looks like it is cut properly. The second pic, not so much. There has to be a slight bit of relief just ahead of the chamber, otherwise the bullet will hit the rifling and not allow the cartridge to fully chamber. The relieved area is called the throat/leade IIRC.
That said, it's easy to see why the gun won't shoot well. The bullet is engaging the rifling on one side before it does on the other..basically tilting the bullet slightly off axis. I'd bet a slow motion video of a bullet exiting the barrel would show quite a bit of wobble. |
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Your pictures were shot at two different angles so the length of the throat appears to change from one picture to the other. You can see through the bore on one picture and not the other.
The rifling is dirty, but the ends of the rifling are sharp. This barrel does not appear to be worn. Since it has sharp edges on the lands (the raised parts of the rifling; the deep parts are the grooves) you can measure the ends of the lands with a Vernier caliper and test them. I'll bet that the ends are within three thousandsths of an inch of each other. Also, the chamber is filthy. Clean it. It looks like a the barrel from an M&P in .40 Smith and Wesson. Shoot it more. I think you just have to practice with it, especially if it's the compact model. |