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Re: How much bump?
I bump my . 308 only 1.5 to 2 thou. I keep a clean chamber though. 3 thou should preserve your brass and chamber fine as long a s you don't get a piece of gravel in there
I bump the shoulders of my semi's 3 thou and never had a problem, but I don't put more than a couple hundred through them before a cleaning.
YMMV........
I bump my . 308 only 1.5 to 2 thou. I keep a clean chamber though. 3 thou should preserve your brass and chamber fine as long a s you don't get a piece of gravel in there
I bump the shoulders of my semi's 3 thou and never had a problem, but I don't put more than a couple hundred through them before a cleaning.
YMMV........
Re: How much bump?
0.002 is plenty of tollerance (depending on your definition of "a little dirty"). 300 clean rounds through a std sized (clean at the beginning) chamber will not suffer failures to feed with this kind of tollerance.
It is almost impossible to set the shoulders back 0.001! Why? Because the (well lubricated) brass in the die will spring back from the die's compression, just like the brass in a chamber springs back after the firing cycle. In order to get the die to "take" the sizing operation, you have to get the pressue on the brass up to the yeild point. I find this means the brass has to be sized at least 0.0015 (with my dies:Redding).
0.002 is plenty of tollerance (depending on your definition of "a little dirty"). 300 clean rounds through a std sized (clean at the beginning) chamber will not suffer failures to feed with this kind of tollerance.
It is almost impossible to set the shoulders back 0.001! Why? Because the (well lubricated) brass in the die will spring back from the die's compression, just like the brass in a chamber springs back after the firing cycle. In order to get the die to "take" the sizing operation, you have to get the pressue on the brass up to the yeild point. I find this means the brass has to be sized at least 0.0015 (with my dies:Redding).
Re: How much bump?
.003 for semi's?
.003 for semi's?
Re: How much bump?
Dusty, with .002 you should be fine. However, consider that there are variables in this. Type and amount of case lube matters. Age/used brass gets harder - less spring. And of course case manufacture. So, the reality of holding a +/- of .001 can be difficult unless you sort cases, anneal etc.. Find something that works in YOUR weapon - they are not all the same. Also, and I never see folks talk about this - lube the back side of the locking lugs on the bolt. That's what takes all the effort in closing, and what galls when cases don't fit.
Dusty, with .002 you should be fine. However, consider that there are variables in this. Type and amount of case lube matters. Age/used brass gets harder - less spring. And of course case manufacture. So, the reality of holding a +/- of .001 can be difficult unless you sort cases, anneal etc.. Find something that works in YOUR weapon - they are not all the same. Also, and I never see folks talk about this - lube the back side of the locking lugs on the bolt. That's what takes all the effort in closing, and what galls when cases don't fit.
Re: How much bump?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wannashootit</div><div class="ubbcode-body">.003 for semi's? </div></div>
I'll consider this quote a question to something I wrote and try to explain. I do this because I consider this particular forum a place to learn and possibly pass on some knowledge earned the hard way to others. I have been at it a long time and I am still learning, so here goes nuthin Wannashootit.
The reason I bump the shoulders for my semi's .003" is simple. That is the distance where the brass chambers with no amount of resistance plus a tiny bit more <span style="font-weight: bold">FOR MY RIFLES</span>. Somewhere around .002+ the brass would rechamber but I added a touch more to make sure I would not have to slam a loaded round out. I found out the hard way years ago what happens when you size for semi's like you do for boltguns.... stuck cartridges.
Try and drop that cleaned but unsized piece of brass back in the chamber of your AR and see how far it goes.
In short, I want to make sure that the brass will chamber without having to resort to any amount of force such as dropping the bolt or using the FA. I want it to go in nice and easy but with the brass sized minimally <span style="font-weight: bold">FOR THAT GUN</span>. I use Winchester for .223 and Lapua/AA for 6.5 Grendel and I anneal all of it at least every 3 loads. It is nice having a BenchSource! I guess it goes without saying that I also trim when necessary.
I have 3 AR's with one being a 6.5 Grendel and 2 being .223 Wylde chambers. I can get away with sizing the brass the same for both .223's so I got lucky there. These rifles are not considered tools, but target rifles, so I don't abuse them and I do not worry about dirty chambers possibly causing issues.
Glen Zediker's book, explains it much better than I.
This all was just my $.02.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wannashootit</div><div class="ubbcode-body">.003 for semi's? </div></div>
I'll consider this quote a question to something I wrote and try to explain. I do this because I consider this particular forum a place to learn and possibly pass on some knowledge earned the hard way to others. I have been at it a long time and I am still learning, so here goes nuthin Wannashootit.
The reason I bump the shoulders for my semi's .003" is simple. That is the distance where the brass chambers with no amount of resistance plus a tiny bit more <span style="font-weight: bold">FOR MY RIFLES</span>. Somewhere around .002+ the brass would rechamber but I added a touch more to make sure I would not have to slam a loaded round out. I found out the hard way years ago what happens when you size for semi's like you do for boltguns.... stuck cartridges.
Try and drop that cleaned but unsized piece of brass back in the chamber of your AR and see how far it goes.
In short, I want to make sure that the brass will chamber without having to resort to any amount of force such as dropping the bolt or using the FA. I want it to go in nice and easy but with the brass sized minimally <span style="font-weight: bold">FOR THAT GUN</span>. I use Winchester for .223 and Lapua/AA for 6.5 Grendel and I anneal all of it at least every 3 loads. It is nice having a BenchSource! I guess it goes without saying that I also trim when necessary.
I have 3 AR's with one being a 6.5 Grendel and 2 being .223 Wylde chambers. I can get away with sizing the brass the same for both .223's so I got lucky there. These rifles are not considered tools, but target rifles, so I don't abuse them and I do not worry about dirty chambers possibly causing issues.
Glen Zediker's book, explains it much better than I.
This all was just my $.02.
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