jdgabbard
01-13-2013, 04:11 PM
As some of you may know, I've been troubleshooting a Sigma recently. I had bought the Sigma back in late April or May of 2012. Price paid for something like $279, and it came with two magazines. Now because of some schooling I'm doing and the fact that I've been working full time I haven't been able to get to the range a tenth as much as I would like to. The only real problem has been finding a load that doesn't lead the barrel horribly. Accuracy is decent, and probably better than I am capable of. I'm able to keep most if not all shots on a 6" bull at 15-20 yards (My eyes are beginning to go bad :( ... ). The big issue has been finding a load that doesn't leave the barrel looking like a sewer pipe. The last session to the range revealed a few things to me. I was satisfied with the accuracy of the load. Secondly, I noticed that the leading started out close to the chamber, and slowly worked it's way to the end of the barrel, but didn't really accumulate once the leading started. That is, it didn't build up, so to speak. It just developed, then didn't get any worse in that spot. Now, leading in this area suggests that the boolits are undersided. This I can rebuttle with the barrel slugging at .3555ish. While the boolits measure .3560-.3565. Now this is taking into account the precision of my micrometer, which is +/- .0005. So it stands to reason, that the size of the boolits could be the culprit.
However... I also was shooting up a batch of boolits, .358242 120gr that were lubed with a slightly modified OLD NRA formula. The next batch that I'm going to be running through it will start off with 100 of the same, but lubed with Carnuba Red. Then 100 of the Old NRA lube to see if leading develops before or afterwards. My theory being, that the lube is just sub-standard. The reason I'm thinking this, is that the load is accurate. In my experience I've had poor accuracy with loads that lead the barrel as much as this does, so I'm thinking I've got the size down, the lube just isn't doing it's job. Which is weird, because I don't have a problem with that lube in the .38spl loads I've used it for.
However... I also was shooting up a batch of boolits, .358242 120gr that were lubed with a slightly modified OLD NRA formula. The next batch that I'm going to be running through it will start off with 100 of the same, but lubed with Carnuba Red. Then 100 of the Old NRA lube to see if leading develops before or afterwards. My theory being, that the lube is just sub-standard. The reason I'm thinking this, is that the load is accurate. In my experience I've had poor accuracy with loads that lead the barrel as much as this does, so I'm thinking I've got the size down, the lube just isn't doing it's job. Which is weird, because I don't have a problem with that lube in the .38spl loads I've used it for.