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Post by sockethead on Aug 21, 2022 10:53:06 GMT -5
Just wondering how you guys are setting up your powder chambers. Are you using the minor diameter of the breech plug threads and simply cutting that bore as deep as needed? Or are you boring it out to a larger diameter with an offset boring bar? I'm using a 5/8-18 HIS breech plug and plan on drilling it out 9/16" and then reaming to 14.5mm (.571"). My gut says to use the reamer for this because of potential rigidity issues with a long, skinny boring bar. And .571" is already a bit larger than a RUM/WSM chamber.
Also, any recommendations on how big to make the chamber for a BH209 gun? My calculations say I need roughly 2.1" deep to hold a 100 grain by weight charge of Blackhorn (10 grains inside the breech plug, 90 grains in the powder chamber). I'm thinking somewhere around 1.5 to 1.7" just to be safe? This is a 45 cal barrel and I plan on starting out with Pittman 300s.
Thanks in advance!
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Post by hillbill on Aug 21, 2022 13:40:20 GMT -5
JMO but unless you are shooting very large doses of powder in a .45 the advantage of a chamber is minuscule, .458 vs .571 is only .113 over a very short space you are not gaining much,with a huge volume load yes it would make a difference. in a .40 or smaller caliber you are gaining a good bit. not to say you can't make a chamber but for loads less than 120 grains or so I wouldn't bother.
I normally go 1.750 past the shoulder and call it good, that gives a bit of a chamber but nothing to worry over.
Again, just one opinion.
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Post by sockethead on Aug 21, 2022 22:36:04 GMT -5
Thanks for the input. Looks like it would make the powder column about 1.2" shorter for a 100 grain load by weight. That's assuming the entire charge is in the powder chamber. I'm not trying to push the limits, and it's very possible I'll shoot smokeless through this gun at some point. I'll probably do like you say and go somewhere in the middle to be safe.
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Post by Hank on Aug 22, 2022 7:28:25 GMT -5
Remember if you cut a chamber for, let’s say, 100 grains, then you will always be forced to shoot 100 grains, or the equivalent to fill the chamber. If you keep your chamber short and decide to change powders or bullets someday, you will still be able to do so. Also, drill the barrel to 9/16 and then tap it. you do not need to ream it out to .571. The 6/16 drill is plenty and will give you a bit more thread height.
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Post by sockethead on Aug 22, 2022 10:33:35 GMT -5
Interesting points, Hank. I'll drill it out to 9/16 and see how the surface finish looks. I was planning to use the reamer for getting a good finish, and also the specs on that thread say .565-.573 for a class 3B. A bit more thread height would be nice, and I doubt the tap will have any issues since 18 tpi is not a very deep cut.
Back to the size of the chamber...I took some measurements with smokeless powder and was surprised to see that a standard load takes up about half the volume of BH209. So if I want this gun to remain compatible with smokeless I'll have to cut the chamber no longer than about 1".
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