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Re: marks on bullets
Posted by Larry Gibson on Wednesday, 27 July 2011, at 11:13 a.m., in response to Re: marks on bullets, posted by steven gabrielli on Tuesday, 26 July 2011, at 7:08 a.m.
Have to disagree here. We're talking a cast bullet here and an undersized one (.458?) at that. The alloy is relatively soft, the psi were talking is relatively low and there won't be any difference in psi by backing off the bullet. How do i know? I have tried to measure any indication of just such a "pressure spike" in my own TD using an Oehler M43. If there is any difference it was well within the small psi shot to shot variation. The bullet I used was the Lee 405HB. I tested with 55 gr and 70 gr loads of Goex 3f and Goex Cartridge. I also tested my duplex carbine and rifle loads. The bullets were seated so the driving band was not engraved by the leade, was half engraved and was fully engraved. Only noticeable difference was accuracy; it improved with the bullet being half engraved. The psi and velocitiy figures remained content with no discernable difference.
Consider that breach loading of bullets in single shot matches is considered the best and most accurate method.
Also unles a carbine load is wanted I'd bump the charge back up and compress it for better, cleaner burning with 400 gr bullets. I'd also look for some .460+ sized soft cast bullets. As to HB'd bullets keep in mind that the HB of the Lee replicant of the M1873 bullet is there to control the weight of the bullet given specific external dimensions. It is not there to expand ala a minie bullet. The skirt is to thick unless almost pure lead alloy is used. There are some commercial HB bullets available that do have thinner skirts for minie type expansion. These work well for carbine level loads but most rifle loads will blow the skrt and inaccuracy will result.
With a good TD rifle, a proper fitting bullet of proper design and weight and if you can hold hard 1 1/2 moa is quite possible.
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