I usually can hold to .001 between low and high, but may get a few closer .0015's (maybe 3 out 50). This is with 30br case's that haven't been annealed ever with probably 7/8 firings on them. Just wondering what kinda tolerance spread (for lack of better words) others are getting when they are bumping there shoulders back?
Shoulder Bump Tolerance
- Thread starter sqrlgtr
- Start date
I range anywhere from .001 to .002 most of the time with an occasional .003 but my press is over 50 years. I personally would be very happy with the small variation you are obtaining.
I don't anneal either but doing so probably provides more consistency however I haven't detected any changes in performance with the values and methods I'm obtaining.
Consistency in application of sizing lube, sizing technique and measuring technique can increase more uniform measurements. Also dedicating a group of cases from the same lot to a specific rifle and rotating their use can increase uniformity.
In addition, I use a single piece caliber specific bump gauge, (Whidden) which eliminates interfaces between the holder and insert. If you're using a two-piece gauge, apply match marks to each piece so you align them the same way each time if you're changing out inserts for another caliber.
I don't anneal either but doing so probably provides more consistency however I haven't detected any changes in performance with the values and methods I'm obtaining.
Consistency in application of sizing lube, sizing technique and measuring technique can increase more uniform measurements. Also dedicating a group of cases from the same lot to a specific rifle and rotating their use can increase uniformity.
In addition, I use a single piece caliber specific bump gauge, (Whidden) which eliminates interfaces between the holder and insert. If you're using a two-piece gauge, apply match marks to each piece so you align them the same way each time if you're changing out inserts for another caliber.
Yeah I was just wondering about the annealing,would that bring all the brass back to a uniform hardness in the shoulder area and make it more consistent IDK...
I have noticed how I lube the case's has a big affect on the cosistency of the shoulder bump. I have better luck with imperial...
Im thinking that it would be hard to improve on my results, especial with my measuring tools lol,but was just wondering what others thoughts were on the subject......
I was a machinist at one time but that was a life time ago now lol....
K22 Thanks for your input...
I have noticed how I lube the case's has a big affect on the cosistency of the shoulder bump. I have better luck with imperial...
Im thinking that it would be hard to improve on my results, especial with my measuring tools lol,but was just wondering what others thoughts were on the subject......
I was a machinist at one time but that was a life time ago now lol....
K22 Thanks for your input...
I normally will see .001 or less differential with shoulder bump. I agree, I feel it is proportionate to the lube application method. I use the Lee (white stuff) or Imperial and have found thru experimenting the best way for me to apply the lube is to put the lube (just a bit) into a small plastic container with a lid on it and shake it for a min or so. It seems to be more evenly applied than any other method I've tried. I do not anneal my brass. Paying attention to the evenly amount of pressure applied to the press handle at the bottom of the stoke also helps in consistency as well. It is important to make sure the inserts are fitted into the holder in the same orientation if using a two piece tool.
do you anneal?
I forgot I do cam over and have a 4 second dwell,well just count to 4 lol...
Also this is with a redding body die,no particular reason for the body die but it was all I could find when looking for dies.... body die, type s bushing die, and then le wilson arbor seater. I have threatend to get a full length bushing die but its working for now, just an extra step....
Concerning the the comparotor its just the hornady out fit and it stays on a dedicated pair of calibers, and yes if you change the insert in and out it will measure different from the last time.....I did get one of the caliper jaw bases from a member here cant recall his handle), and it does help getting a consistent reading......
Dusty Stevens
Shiner
Do not put lube on the shoulder or neck only the body. You shouldnt vary a thou if you have good dies and your brass is in good shape.
Murray Brook
Silver $$ Contributor
Mike Do you use a neck lube for your 1'st firing after annealing. Reason I ask is I too anneal the dip method way and find that if I do not use a lube ( Imperial dry lube ) my groups are off till I get past the first firing . I find the Imperial make such a mess.
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I really like Imperial sizing wax. It does a super job, lasts a long time, and is economical. I apply it with my fingers spreading it sparingly and uniformly over the body of the case avoiding the shoulder area.
It does a great job.
I have been putting imperial lube on case shoulder and body but not neck but if I hadn't been using body die I'm sure I would have been putting it on neck also lol... I do use the graphite that comes with the little balls mixed into it on necks before they go into the neck bushing die. Will try just putting it on case body only next go around. I do bump shoulder every firing also....Would a case checker with the dial indicator on top be a better way to measure ? PMA makes a nice looking one that I've been eyeballing.
Don't lube the neck or shoulder? What is the negative from lubing the neck and shoulder?
I agree that consistency of lube application is a big factor. Also, the deflection of the press is a big factor as well. I reduced my sizing variation significantly when I went from a Forster CoAx and RCBS RC Supreme to a Prazipress.
Assuming I can really measure to .0005" with Mitituyo digital calipers, I keep my sizing variation within .0005". I set up the die so that if anything happens it leans long, and I'll just size again if needed. I start out with almost no variation is shoulder length, but as the lube dries out a little on the pad--use RCBS lube on a lube pad--the sizing goes a little longer until I relube.
Assuming I can really measure to .0005" with Mitituyo digital calipers, I keep my sizing variation within .0005". I set up the die so that if anything happens it leans long, and I'll just size again if needed. I start out with almost no variation is shoulder length, but as the lube dries out a little on the pad--use RCBS lube on a lube pad--the sizing goes a little longer until I relube.
Just my 2 cents worth and if you're maintaining .0005 consistency then it probably doesn't pertain to you. But, I find that a small amount of variability is normal, as in about .001. For that reason, I tend to bump my shoulders a tad more than some others do. My logic is simply that I'd rather have all cases to have easy bolt closure as opposed to some being tight and some loose. I find that scenario to be very common when we try to achieve .0005ish shoulder bump. Now, I won't take this to extremes but I don't consider .002-.003 to be excessive shoulder bump, yet enough to ensure a consistent bolt closure, ignition and harmonics. Nothing at all wrong with being a little closer to "perfect" but I don't find it to matter as much as tight vs loose.
My brass life has never come down to this. It's always been primer pockets that go first for me.
Again, just my 2 cents.
My brass life has never come down to this. It's always been primer pockets that go first for me.
Again, just my 2 cents.
When I sorted bumped brass into .0005 & .001 categories to test for group size @ 100 yds. there was very little difference in the agg. for both sets of groups. Both maintained less than 1/4 " groups. Tested with 30BR.
I think to a point, clearance is clearance and you either have some or ya don't. Of course, this is not about excess in either direction.
My bullets are WS2 (dry lube) coated, so I don't need to worry about high seating friction and resultant CBTO variances. I don't use lube for necks specifically (inside or out), ever.
For groups to be 'off' with new brass is pretty normal.
Dusty Stevens
Shiner
You cant lube it consistently and it builds up in the die and varies wildly on bump. You dont need any lube on the neck or shoulder- this is why a lube pad only lubes the body. You can use the dry lube with the ceramic balls for the inside of the neck if you use an expander, but if youre using an expander your case bump will vary wildly due to that anyway
Murray Brook
Silver $$ Contributor
What I mean is first firing after every anneal.
Ok, slightly off subject but how can you anneal thicker shoulder brass, to affect bump, without over annealing thinner neck brass. Asking for a friend.
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