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Post by exmachina on Oct 25, 2017 7:23:50 GMT -5
The fix entailed grinding a 4 degree lead into the reamer, then putting radius on the lower edge. Shops like Pacific, Manson, or JGS could modify off-the-shelf .500 reamers with ease.  Thanks for the great post. I'm looking into the same issue and have been advised that I want a 0.502" reamer for 0.501" bullets. Could you breifly explain the thinking behind a 0.500" reamer? EDIT: or is the explanation simply that 0.500" reamers are easier to source?...sometimes I'm not to swift before my coffee  |
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Odin
.375 Atomic
Posts: 1,103
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Post by Odin on Nov 1, 2017 0:58:14 GMT -5
Thanks for the great post. I'm looking into the same issue and have been advised that I want a 0.502" reamer for 0.501" bullets. Could you breifly explain the thinking behind a 0.500" reamer? EDIT: or is the explanation simply that 0.500" reamers are easier to source?...sometimes I'm not to swift before my coffee I've loaded a goodly number of cases in my day, but I'm by no means an expert. That being said, it seems to me the simple answer to your question is neck tension. Neck tension is the main "force" holding the bullet in the case (crimp helps too, but to a lesser degree). If you ream a case to .502 and drop in a bullet sized to .501, there's no part of the case actually holding onto the bullet. By reaming to .500, you create a situation where upon seating the bullet, the case stretches just a bit, thereby providing enough tension to hold the bullet well, but not stretch the case wall so much that you're needlessly overworking the brass. |
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Post by exmachina on Nov 2, 2017 7:12:44 GMT -5
I've loaded a goodly number of cases in my day, but I'm by no means an expert. That being said, it seems to me the simple answer to your question is neck tension. Neck tension is the main "force" holding the bullet in the case (crimp helps too, but to a lesser degree). If you ream a case to .502 and drop in a bullet sized to .501, there's no part of the case actually holding onto the bullet. By reaming to .500, you create a situation where upon seating the bullet, the case stretches just a bit, thereby providing enough tension to hold the bullet well, but not stretch the case wall so much that you're needlessly overworking the brass. Makes sense but why would the manufacturer of neck reamers reccommend this?--for example Forster has a spec sheet recommending reamers be 0.0025" larger than bullet diameter For me, I ended up ordered in 0.501" reamer but have not tried it out yet. Still seems better to as large/larger to avoid bulging the case. Without reaming, my cut-down Starline brass is bulging noticably even with 0.500" bullets. |
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Odin
.375 Atomic
Posts: 1,103
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Post by Odin on Nov 2, 2017 13:04:54 GMT -5
Forster states ( here) that reaming should be performed AFTER firing full power loads and BEFORE sizing the case. And while it's rather foolhardy to assume, I'll go ahead and say it... I assume Lee is talking about reaming the case (not really the neck now is it) AFTER full length sizing. Again, this is only needed for 500+ grain bullets, where the bullet is so long it begins running into the portion of the brass that naturally grows thicker as it nears the web of the case. With bullets in the normal range, say 440-480 grains, there shouldn't be a seating issue. I will say, that more details about your specific situation, including pics and measurements, would be most helpful at this point and may entice some of the more experienced handloaders to chime in. |
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Post by exmachina on Nov 2, 2017 13:58:36 GMT -5
My situation is this: my trimmed down (new, unfired) Starline brass (sized) has an ID that is several thousands under the bullet diameter (can't remember exactly but I think I was at most 0.495"). That means that the RCBS expanding die bulges out the sized cases AND then, a 0.500" (350gr) bullet bulges them out even more (basically I end up with two "ripples" in my finished cartridge). Been reloading for a while and I've never encounterd either of these problems with any other caliber. But maybe it's just a quirk of this round?--I noticed Buffalo Bore 440gr loads also show a bulge in their 500JRH loadings...
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Odin
.375 Atomic
Posts: 1,103
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Post by Odin on Nov 2, 2017 19:17:46 GMT -5
Which bullets? Does a finished round chamber in your gun? Can you post a picture of a finished round?
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Post by Lee Martin on Nov 2, 2017 19:27:17 GMT -5
Could you breifly explain the thinking behind a 0.500" reamer? Start with the FL sizer, determine how much neck tension you want, tube mic wall thickness, then chose the reamer size. Boring fired cases with a 0.500" reamer gave me 0.0136" average wall thickness: O.D I.D. Fired Case * 0.532" 0.505" Sized Case 0.522" 0.495" Loaded Round ^ 0.528" Chamber Dia. 0.533" Total Clearance 0.005" Neck Tension 0.006" * - 0.001” spring back observed ^ - (0.501+ 0.0136 + 0.0136) - confirmed with a micrometer -Lee www.singleactions.com"Chasing perfection five shots at a time" |
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Post by exmachina on Nov 3, 2017 8:16:32 GMT -5
Could you breifly explain the thinking behind a 0.500" reamer? Start with the FL sizer, determine how much neck tension you want, tube mic wall thickness, then chose the reamer size. Boring fired cases with a 0.500" reamer gave me 0.0136" average wall thickness: O.D I.D. Fired Case * 0.532" 0.505" Sized Case 0.522" 0.495" Loaded Round ^ 0.528" Chamber Dia. 0.533" Total Clearance 0.005" Neck Tension 0.006" * - 0.001” spring back observed ^ - (0.501+ 0.0136 + 0.0136) - confirmed with a micrometer -Lee www.singleactions.com"Chasing perfection five shots at a time" Thank you! Very informative. My measurments seem to generally be in line with yours. |
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