I am having some issues with consistency when I resize my 6.5x47 brass. I assume that if I am trying to size my brass to 1.4655 then it should probably never get outside of 1.4665 to 1.4645. Does this sound reasonable? I actually feel like it should stay within .0005, but I am new to this endeavor.
How consistent are your full length resizing numbers?
- Thread starter Toemader
- Start date
It all depends on the particular process involved. For example, it's easier to get consistent within .0005 when one also properly anneals their brass. Another thing that helps is how consistent the brass is lubed for sizing. And having enough "dwell time" (the amount of time the brass sits fully in the sizing die) reduces the amount of springback when the brass is removed. Quality of the brass you're working with also can make a difference as can the use of an expander ball in the die.
Today I just finished 100 pieces of Lapua .308 brass and checking samples, most were at +/- .0005 of my target and only found a couple that were ~.001 off. I do all three of the above. I use Imperial Sizing Die Wax the produces very good lubrication and let the cases dwell in the die for 4-5 seconds as I prep the next case with lube.
I'd say, if you're not annealing and not dwelling, that range of 1.4645 to 1.4665 is not unusual.
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RegionRat
Gold $$ Contributor
As a beginner, try to keep enough margin to be able to close the bolt.
How much is that?!?....
Stick to small batches at first. Roughly 20 pieces or so.
Use the advice above and do your best to get the lube and workmanship to your best.
Use the instruments to measure the cases, but then make sure you also test with your chamber at first.
If you find your results allow you to play it closer the next time, then by all means try it but be realistic about your actual values. There will always be some amount of dispersion in the measurements. Make sure your target value allows the worst one to maintain a margin to close the bolt.
By sticking to small batches at first, you will get more learning cycles in sooner. As you gain experience and confidence, you will know when it is time to use less margin and let the cases get "tighter".
When your process and capability gets better, then you can attempt larger batches and be confident you know what you are doing.
Good Luck and have fun.
Merry Christmas
How much is that?!?....
Stick to small batches at first. Roughly 20 pieces or so.
Use the advice above and do your best to get the lube and workmanship to your best.
Use the instruments to measure the cases, but then make sure you also test with your chamber at first.
If you find your results allow you to play it closer the next time, then by all means try it but be realistic about your actual values. There will always be some amount of dispersion in the measurements. Make sure your target value allows the worst one to maintain a margin to close the bolt.
By sticking to small batches at first, you will get more learning cycles in sooner. As you gain experience and confidence, you will know when it is time to use less margin and let the cases get "tighter".
When your process and capability gets better, then you can attempt larger batches and be confident you know what you are doing.
Good Luck and have fun.
Merry Christmas
jepp2
Gold $$ Contributor
Really nothing to be gained by sizing this close. But if you are using a caliper system to measure it, you will never know due to the measuring capability of the system. So many other things to focus on that are much more important.
You could shoot those cases that have the most variances side by side with your best load and note if it made any difference on the target.
If I couldn't hold a tolerance of +-.0002 I'd sell it all off and buy a good set of golf clubs. Look for a problem elsewhere.
6BRA
Gold $$ Contributor
.0005 every 3 rounds qtip the die shoulders. You will be suprised of lube buildup. If you are screwing the die in the press this could be a pain in the ass. Coax has benefits. Pressure and process could knock you off from flex. Your comparator needs to be matched shoulder angle and again pressure on the comparator needs to be consistent. Very rarely do I hit .001 . Annealing every firing.
I'm not expert, but.... I focus on the case shoulder.... 1-3 thou off the chamber dimension, but consistency is the main key.
OAL case length = anything under SAAMI spec. If too short a neck to seat consistently, I chuck the case.
I've gotten good results using this method... 0.3 - 0.4" @ 100 yd, and good repeatable hits out to 1000 yd. tho admittedly, I'm no benchrester.
OAL case length = anything under SAAMI spec. If too short a neck to seat consistently, I chuck the case.
I've gotten good results using this method... 0.3 - 0.4" @ 100 yd, and good repeatable hits out to 1000 yd. tho admittedly, I'm no benchrester.
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jelenko
Gold $$ Contributor
Before going down this path, what are you wanting to do with the rifle? E.g., plinking, steel targets, PRS, Benchrest, F Class, Cross, the Course - what ever.
The accuracy requirements vary significantly => the requirements on 'process control' for ammo vary accordingly.
The accuracy requirements vary significantly => the requirements on 'process control' for ammo vary accordingly.
I think your standard of .0005 is reasonable. I also think experience and developing consistency in your sizing process and measuring consistency will get you from +/- .001 to your goal of .0005. As others have stated the type of equipment, the quality of your brass, the number of firings, annealing or not, dwell time at full stroke are some of the things that will make a difference. Consistency in everything you do will lead you to the fruit of your endeavor. Closely monitor your progress and don't be afraid to try things (within reason).
If I couldn't hold a tolerance of +-.0002 I'd sell it all off and buy a good set of golf clubs. Look for a problem elsewhere.
-+ 2 ten thousandths on shoulder bump?
What are the accuracy requirements of your shooting discipline?
Many of the previous posts in this thread address the issues for obtaining consistency in sizing. Dedicating a group of cases to a specific rifle and rotating their use will also help. Measuring consistency is also a factor as noted in post #7.
A friend of mine was using a Hornady bump gauge tool which employs the use of caliber group specific inserts. He was also using the anvil attachment on the opposite jaw of the caliper. His measurements were terribly inconsistent. We discovered that the anil was not cut parallel and the inserts when disassembled and reassembled aligned differently. We got rid of the anvil, inscribed match mark of the insert and holder so the alignment would be consistent. This is one of the reasons I like the Whidden single piece bump gauge - there are no inserts. We also worked on refining his measurement technique, rotating the case while applying pressure to the caliper taking multiple measurements until his technique produced consistent measurements. The point of this long epistle is that measurement inconsistently can be a significant issue that distorts results.
The other point I would make is that do your really need that level of sizing precision to produce the results that you need on target. Testing will answer that question quite succinctly.
I have never been able to hold .0002" as post # 8 states but I didn't "sell off everything" and buy a set of golf clubs for two reasons, first, I can achieve results on target without anywhere near that level of sizing consistency and secondly, I could never play golf well because I'd always be focused on the tree lines looking for ground hogs.
Just remember, the only reason we have to size cases is so the cartridge will reliably chamber in the rifle and hold the bullet. Optimum sizing accomplishes reliable chambering by not over sizing thus over working the cases and produces consistent neck tension.
Many of the previous posts in this thread address the issues for obtaining consistency in sizing. Dedicating a group of cases to a specific rifle and rotating their use will also help. Measuring consistency is also a factor as noted in post #7.
A friend of mine was using a Hornady bump gauge tool which employs the use of caliber group specific inserts. He was also using the anvil attachment on the opposite jaw of the caliper. His measurements were terribly inconsistent. We discovered that the anil was not cut parallel and the inserts when disassembled and reassembled aligned differently. We got rid of the anvil, inscribed match mark of the insert and holder so the alignment would be consistent. This is one of the reasons I like the Whidden single piece bump gauge - there are no inserts. We also worked on refining his measurement technique, rotating the case while applying pressure to the caliper taking multiple measurements until his technique produced consistent measurements. The point of this long epistle is that measurement inconsistently can be a significant issue that distorts results.
The other point I would make is that do your really need that level of sizing precision to produce the results that you need on target. Testing will answer that question quite succinctly.
I have never been able to hold .0002" as post # 8 states but I didn't "sell off everything" and buy a set of golf clubs for two reasons, first, I can achieve results on target without anywhere near that level of sizing consistency and secondly, I could never play golf well because I'd always be focused on the tree lines looking for ground hogs.
Just remember, the only reason we have to size cases is so the cartridge will reliably chamber in the rifle and hold the bullet. Optimum sizing accomplishes reliable chambering by not over sizing thus over working the cases and produces consistent neck tension.
Can you give details about your brass prep, press design, if your keeping your brass on the same cycle, etc?
I can usually hold my brass to within 1/2K when sizing but it took some trial and error. First thing is to keep your lot of brass on the same cycle. If possible, use a hood/fully bridge style press (I get more variance with press designs, like a coax). If your applying an imperial wax on a pad, make sure to reapply very often for consistency (your shoulder bump will increase with too much lube and less with too little).
It’s a little time consuming but before I found the correct method for consistency, I would measure each case, set the one‘s that didn’t bump enough to the side, and then send them through the press again until they were within that 1/2K variance.
Remember to keep your press speed and dwell time consistent also...
My smith makes me a bump gage from a barrel stub, using the same reamer used to cut the chamber. I use a co-ax press and anneal after every firing. Clean excess lube out of the every 5 rounds. Count 3 at the top of the stroke. All this results in 1.4545 to 1.4550. Trial and error to arrive at this point.
Some other note: use a good quality caliper (Mitutoyo, Starret). Keep the jaws clean. Have spare batteries.
PopCharlie
Some other note: use a good quality caliper (Mitutoyo, Starret). Keep the jaws clean. Have spare batteries.
PopCharlie
Err to the loose side as opposed to having some feel on bolt closure on some and none on others. I bump further than most do but I haven't seen a problem and I do it this way for that reason. Trying for .0005 clearance will typically leave some a tad tight and others not. Just saying, I'd rather them all be a little loose rather than some of both loose and tight. Consistency is something else and the others have given good advice there.
My understanding is consistent bump creates accuracy, minimal bump (w/o hard bolt closure) extends brass life.
But I am wrong about many things.
Ned Ludd
Silver $$ Contributor
I measure 10 cases after each criticsl step during brass prep. It is not uncommon for the base-to-shoulder measurement of all 10 cases to be identical according to the caliper tool. In my hands, the base-to-shoulder dimension seems to be one of the most consistent measurement I take. Nonetheless, I occasionally find one that differs by .0005" or .001" [i.e. smaller than the desired value, never larger]. I don't find this troublesome at all. A variance of .002" or greater might get my attention.
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jackieschmidt
Gold $$ Contributor
Most Short Range Benchrest Shooters get pretty aggressive with the shoulder bump and body sizing. You want the cases going in easy and coming out easy.
Granted, they will come on here and throw around ridiculously small tolerances in “tenths”, when in reality most are in the .002to .003 range on the shoulder bump. Many do not want to say what they really do, and what really works, because of the perceptions that are out there.
As has been noted, if you are wanting to measure in very small numbers, you need the tools to do it. And, you need to be proficient in using them.
The one thing you never want to rely on is “Feel”. I have Seen shooters keep sizing down untill the bolt drops easy, thinking they finall y have about .001 bump, when in actuality had as much as .010.
There more are things that influence this than simply pushing the shoulder back.
Many of us who have the means and time to do it have experimented with just about every sizing combination imaginable. The truth is, it simply doesn’t matter that much until you get into a potentially hazardous situation of entirely too much headspace that can lead to a head separation after numerous firings.
A while back, a fellow Benchrest Shooter and friend of mine, were discussing some of the topics on the Internet, and he made an interesting statement. It kinda went like…..”Benchrest shooters, who shoot groups measured in thousandths of an inch, work in numbers to the nearest “thousanth” of an inch. Shooters who shoot at 12” diameter pie plates and consider a hit good enough work in “one ten thousanth” of an inch”
He was being facetious, but there might be some truth to that.
Granted, they will come on here and throw around ridiculously small tolerances in “tenths”, when in reality most are in the .002to .003 range on the shoulder bump. Many do not want to say what they really do, and what really works, because of the perceptions that are out there.
As has been noted, if you are wanting to measure in very small numbers, you need the tools to do it. And, you need to be proficient in using them.
The one thing you never want to rely on is “Feel”. I have Seen shooters keep sizing down untill the bolt drops easy, thinking they finall y have about .001 bump, when in actuality had as much as .010.
There more are things that influence this than simply pushing the shoulder back.
Many of us who have the means and time to do it have experimented with just about every sizing combination imaginable. The truth is, it simply doesn’t matter that much until you get into a potentially hazardous situation of entirely too much headspace that can lead to a head separation after numerous firings.
A while back, a fellow Benchrest Shooter and friend of mine, were discussing some of the topics on the Internet, and he made an interesting statement. It kinda went like…..”Benchrest shooters, who shoot groups measured in thousandths of an inch, work in numbers to the nearest “thousanth” of an inch. Shooters who shoot at 12” diameter pie plates and consider a hit good enough work in “one ten thousanth” of an inch”
He was being facetious, but there might be some truth to that.
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