How much does bump sizing extend case life?

For those of you who bump size your cases, how much does this extend the case life? I load for two different 223 rifles and have done some initial experimenting with it. The two chambers are different enough that I would have to keep the brass separate and have multiple sizer die settings. Just wondering if this is what others do and if it's worth the trouble.

Thanks

Bill

The amount of shoulder bump is the approximate head clearance when the cartridge is chambered. Meaning the distance the case must stretch when fired to contact the bolt face.

https://i.imgur.com/HK76WCp.jpgBelow you can see that Lake City brass is made Ford Truck Tough http://www.savageshooters.com/images/smilies/first.gif


I buy once fired Lake City 5.56 cases because they are made of harder brass than commercial .223 cases. The brands of cases have different hardness and elastic limits, meaning their ability to stretch and spring back to their original size. The recommended shoulder bump amounts are .001 to .002 for a bolt action and .003 to .006 for a semi-auto.

How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests

http://bulletin.accurateshooter.com/2014/05/how-hard-is-your-brass-5-56-and-223-rem-base-hardness-tests/

Below you can see that Lake City brass is made Ford Truck Tough :first:

http://accurateshooter.net/Blog/brasstest03.png

You hit it in one - depends on your chamber. I bump size my .260 Rem but it's not really critical - just one more thing I can control that adds a time bit of accuracy (maybe - more consistent pressures). But I load pretty moderate and the headspace was good from the get-go.

Neck sizing alone will eventually result in too tight a fit, but if you can get a consistent 0.004" bump with reloaded brass you can get maybe 15 or 20 loads before the primer pocket eventually gives out. Or the neck splits. Bumping doesn't help with the case mouth.

Just too many variables in brass, load, chamber to say how many for your rifle vs. another one.

I shoot two Savage 223's one with stock barrel, one with Criterion match and so I keep the brass segregated like you do, but I don't bump size, I only neck size. The brass never grows, will chamber easily if not loaded to the max and even when I do shoot a hot load, it is only slightly stiff on the bolt closure next time around. I do occasionally anneal it however, not that it really needs it as I've loaded some cases dozens of times with no split necks.

I use the Lee collet die which sizes the neck with almost no measurable neck tension however, after a few cycles the neck is about as hard as it's going to get, and seating becomes very consistent with good bullet grip.

And it will shoot tiny groups loaded this way.

I think it's easier in the long run to separate the brass for each rifle, and buy a set of dies for each rifle, that way when you get everything set up/finalized you don't have to adjust the dies much, if any and just reload. I do some testing during load development and find out what brand of brass a rifle "prefers", and just go from there. Sometimes the differences in brass makes a difference, sometimes not. A Rem 700 223 load prefers FC brass, while a FV12 223 load prefers LC. Makes it easy to keep 'em sorted when cleaning brass.

I have Lapua 6 BR brass that has been "bump sized" at least 25+ times and it's still going strong. Primer pockets are still snug. All my loads are mid range so the brass doesn't get hammered. I'am only bumping about .002 so the brass doesn't get moved much. The less it moves, the less it effects the brass. I'll throw in a "body size" when they start getting snug in the chamber. The bolt shows that on closing.
All of my brass is wildcat except for my gas guns.
(you CAN bump gas gun brass if you know what you're doing. Speaking from experience) ;)

Head space is set on the "snug side" on all my rigs. There's no factory brass available for my chambers.
My Lapua brass has been sized to 22 BR, 6 BR and 6.8 BR wildcat. All get the same sizing routine. Bushing bump and body size as/when needed. Some have been annealed as they loose spring back. You can tell that when you resize.
Also, with bump dies, not much if any trimming is needed. The cases don't get a chance to grow. Takes a while to find out what works best. That's the fun part. YMMV, Mikie.:cool:

Once I get a casing to fit a bolt gun chamber I neck size (Lee Collet Die generally) until the bolt balks upon closing. It takes quite a few firings with judicious loading to get to the point where a partial full length or full length resizing is needed.

Three44s