head space and bumping shoulders - further question

S

savet06

Mike Suhie
Didn't want to hi-jack Lee's post, but the discussion on headspace brought up a question that has bugged me for a while...
If the ideal shoulder bump (as measured by your favorite method, I have a barrel stub thingy) is .0005-.001 and you get that measurement by FL sizing, but your brass still doesn't "feel" right (read: handle of a stripped bolt doesnt' drop the aforementioned appropriate distance on a FL/bumped, unloaded case)
what do you do? In fairness, do you do anything? Try to shoot with brass that is more difficult to load and unload or try to get a die that will get you where you want to be?
I have found that I need to bump closer to .002 to get the right feel, but have stopped because better accuracy was had with less bump...downside is that I can't run as fast as I'd like.
Mike
 
Something you have probably already thought of but if you are only sizeing a portion of your neck on the case you might be spacing of the bottom portion of the neck instead of the shoulder and that is why you are having an issue. Just someting that crossed my mind that could help. A lot of good advice is given on the other post so I would stick with that. The shooters there have more experiance and knowledge than me who is still new to the game also. read what they have to say and I think you will find your answer.
 
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Mike, as Goodgrouper said, the culprit might be your full length die simply is not sizing the case body enough.

How many firings on the cases before you notice this? On a die that is marginal, the first few will be just right, but as you put more rounds on the brass, it simply does not respond to the die as it should.

If you know how to use a set of one inch mics properly, you should be able to measure the actual affect that the die has on a fired case. My die hits the web about .0005, and up by the shoulder about .001. I also have an identical die that I turned the bottom 3/8 inch down to about 1/16 thick, then pressed a ring on it, in affect, tightenning up the web portion just a tad more. After 4-5 firings, I run them through this die before the next........jackie
 
I have a FL sizing die that has interchangable inserts for the bottom of the die. There are about 6 different sized inserts. Don't have a clue as to who made it. Bought it at a match couple years ago. Haven't used it very much, but that could be that I just have not experimented with it enough. As far as matching a die to the chamber, can't you go the other way around. If your die doesn't size the base portion of the case enough how about reaming out the bottom of the chamber about .001 or so. Make the chamber just a tad larger than it was. Then the die would size the case properly, as long as it is bumping the shoulder back the right amount.

Donald
 
Thanks for the replies, and, goodgrouper, your explanation does make sense. I noticed the issue after about 4-5 firings, and I did try to mic the web area, but not up by the shoulder. I now have about 20 firings on the brass and I am considering making up a new batch for this season, but before I did that I wanted to make sure I wasn't wasting the pieces. Granted, I do not do this every day and my measurements in the hands of a more experienced machinist would probably be different, but I did get 0.0005 at the web. I will check the shoulder measurement as well.
Thanks, guys.
Mike
 
Goodgrouper has it right. One comment on Donald's post...you wouldn't necessarily ream the back of the chamber larger, but it could easily be polished out a little larger, on a lathe, by someone who is experienced at that sort of thing. Just stay away from the shoulder. For a long term solution, picking up a die that is a little tighter at the back, or a reamer that is just a little larger, would get you there for all your new barrels. The die with the inserts that someone posted about is probably a Harrel's Vari-Base die. I use one, and like it. Once in a while they come up for sale, used.
 
Steve
You never did say what case you specking of. Im assuming a 6ppc? What die do you have?Is it a Harrell's? I had this same issue with a Harrell's die and one of my 30BR's. Harrell's just sent me the wrong die and they exchanged it without question and after re-checking my fired cases. Lynwood offers a pretty good alternative to your situation. Just send him 3 or four fired cases (that have been shot a few times and not resized. just like they would be out of the rifle) and he will match a FL size die the best he can to what you have. I think the dies run around 60 in cash and 70 with a check or CC. Give that a shot and i think your problems will go away. lee
 
Lee,
the round is a 30br and the die isn't a Harrell's but I am contemplating giving them a call. I'd like to get this straightened out before the season starts and I make another hundred cases.
Thanks again,
Mike
 
Yes sir now is the time to get the gear in order! Good luck and i wish you well. give harrells a call!!! Lee
 
Boyd Allen said:
Goodgrouper has it right. One comment on Donald's post...you wouldn't necessarily ream the back of the chamber larger, but it could easily be polished out a little larger, on a lathe, by someone who is experienced at that sort of thing. Just stay away from the shoulder. For a long term solution, picking up a die that is a little tighter at the back, or a reamer that is just a little larger, would get you there for all your new barrels. The die with the inserts that someone posted about is probably a Harrel's Vari-Base die. I use one, and like it. Once in a while they come up for sale, used.
Click to expand...

Ah, Boyd,
I just could not think of the word polishing with a piece of dowel and crocus or very fine wet or dry. But you got the idea. You only have to adjust one or the other. If one has a lath or acces to one polishing out the base portion of the chamber from the shoulder back to the base a tad, say .001-.0015 would be the easiest way to go. The chamber and the resizing dies are kind of like a marriage. It just takes a bit of fine adjustment. One way or tother....... lol..

Donald
 
Mike
Good answers. Hope you got this straightened out.
Just a note to let you know I sent a PM on another subject.
Can't recall if BR Central sends notifications of PM's so I thought I'd use this rather unconventional method=)
 
Would another fix to this problem be to take a skim cut of approx. .010 off bottom of die and the use appropriate shims to get correct shoulder bump & base re-sizing? It appears that some of the commercially available threaded dies have this same problem when trying to re-size brass for tighter chambers.
 
I would rather modify a shell holder, because this leaves the die sizing the maximum length of case body. Down at the bottom, just above the extractor groove, can be a critical area for sizing. By leaving the die alone, you preserve that at its maximum reach down the case. shell holders are soft. A friend cut one back a little on his lathe. He trued up the tips of the jaws on his three jaw, and then chucked it so that the surface that touches the top of the ram was against them. Just a light cut, and he was done.
 
If the little thingy ( shoulder bump gage) was not made with the same reamer your barrel was chambered with, You may not get
a true reading. The radius at the neck shoulder can come into play here and give you false numbers
 
Bob,
Recently I have switched to the little brass tool that Lynwood Harrell furnishes with his dies. For bump gauging I can see no advantage to a close fit, and I can see some potential disadvantages.
Boyd
 
not related to the answer , but to the terms used
HEADSPACE is a is a characteristic of chamber and bolt, and has nothing to do with the CLEARAANCE one provides when sizing brass.
HEAD CLEARANCE is the distance between the head of a fully seated cartridge or shell and the face of the breech bolt when the action is in the closed position. Commonly confused with headspace.
getting down from my soap box and walking away...

mike in co
 
Did this ever get straightened out? Was wondering because I have a similar problem with a 30 Dasher die of mine. But that's because the neck opening in the FL bushing die, a modified 6 Dasher, is too large and doesn't get in close enough to the neck shoulder junction. Thing has to be set to bump a little more than necessary if I want the whole shoulder to move enough for an easy bolt closing.

On the other hand, even with my 19lb+ 30BR rifle I have to make fine adjustments after every shot no matter how smooth that bolt works. So I shoot the 30Dasher with just the neck sizing that it prefers and put up with the stiff bolt, till I get around to having another die made, even though I often run to stay in a condition. Ya, it'd stay closer to center with an easy bolt. But then I wonder what percentage of shots are taken at a score target, where the previous hits can be seen, with the same exact hold as the previous shot? Even when I'm running I'm usually to some degree chasing the last shot or holding different because of slight condition changes.
 
Jackie
What did you yous to turn down the bottom of your die? Ive had people tell me they could not turn off metal off the bottom of my dies after it was heat treated. Thanks max
 
I found a sizing problem by taking a black Sharpie pen and coloring the entire shell and then run it up in the die and it was clear that the die was oversizing near the web and rubbing the marker off in just that area. Somebody on the forum shared that trick some time back and works like a charm.
 
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