Small base dies case stretch ar-15

[Paseclipse]

I have noticed that Rcbs 223 small base dies are stretching my lc 2013 cases..
New case fired .001 to .002 length increase when fired in ar-15. I measure the case and size it with a small base die set correctly for .002 shoulder bump.
The case stretches .005 when sized. Now the case is 1.756, original length 1.750 +.001 from being fired and + .005 from sizing.. Fired only one more time and I am at 1.762. Trim is know necessary. So two firing with small base die and must be trimmed.

A guy at the range uses same exact gun and load lc 2013 case, Hornady fmjbt 55 grain 26.0 grains blc-2 and light crimp. He uses std fl dies works fine in his gun. He could not recall how many times fired before trimming.

My question is if you have no malfunctions using std fl dies about how many times fired before you hav to trim your cases.

When I first started loading 223 I was also on the SBD bandwagon until I figured out it really isn’t needed unless your chamber is on the tight side. SBD’s work brass a lot harder than FL die’s because it’s sizing the brass to the minimum.

Maybe give FL sizing a try and only use SBD’s if you really need to? You’ll probably get more life out of your cases.

Perhaps the .005” case stretch during resizing has something to do with the expander ball pulling through the case neck?

To avoid this problem, I use this secret technique that most reloaders try to avoid. Ready for it? I trim my brass after every firing!

No measuring and sorting or wasting time to keep track of how many times a case has been fired, just clean, trim, load, shoot.

It seems like you waste more time trying to measure and avoid trimming than just running it through the trimmer. I dont need to add another step in my process to slow me down, I just run it through the trimmer. If it only trims a little bit, then it trims a little bit, if it trims more, then it trims more.

^^^^ This.

I do the same thing because it’s faster to run cases through the trimmer than to individually measure each one or even check them in a gauge.

[J-cat]

One benefit of not trimming is a longer neck which helps to stop bullet setback during feeding by virtue of more surface area adhering to the bullet.

[bazineta]

OP, I just trim every time -- I have a Wilson trimmer, and frankly once practiced with it, it's practically as fast to trim as it is to measure, so I just trim.

However, the thing is, unless you have a very tight match chamber, I'd recommend trying a standard die instead of a SB die; no point in working brass without necessity.

[ar15robert]

I shoot .223 out of my mini 14 and ar15 plus i pick up everyone elses in my group who dont reload so i have multiple brass from different guns.

I also use the FL dies and have been doing so for about 16-17 years with no issues.I started with small base dies but found they werent needed for my rifles.I also trim all of my brass after each firing or the brass i get it just makes things easier down the line esp if you do light crimping.Some brass i see more material coming off when trimming others not so much.

[1911colt.ml]

I use the Small base die because I fire my 223 reloads out of several different rifles. Most of my AR type chambers are on the tight side so I like them.

[LynnJr]

When you first get your new brass it has to fit in every chamber including those made for bolt guns.
The chambers in semiautomatic guns tend to be larger so the cases can feed and extract without any jamming issues.
What that means is the brass from a semiautomatic tends to come out larger.
By using a small base die you are now squeezing the base down more than normal and that brass has to go somewhere so it grows in length.
Yes you can just keep trimming it but you are weakening the area right in front of the web by oversizing your brass.
Small base dies are not where you should start they are used when properly set up full length dies are not sizing the base of the case enough for proper functioning.
If standard dies work with your guns chamber you are over working your brass with small base dies and it won't last as long.

[J-cat]

Not true. The extra .001" of sizing at the base does not reduce the life of the case in any meaningful way. I have reloaded FGMM 20 times, yes 20 times, using a small base die. I trimmed .070" of case neck in the process as the case stretched. What goes first is the primer pocket, then the case head, and SB sizing doesn't play into it.

['ol shooter]

A good discussion.

[LynnJr]

Not true. The extra .001" of sizing at the base does not reduce the life of the case in any meaningful way. I have reloaded FGMM 20 times, yes 20 times, using a small base die. I trimmed .070" of case neck in the process as the case stretched. What goes first is the primer pocket, then the case head, and SB sizing doesn't play into it.

100% wrong.
If your trimming brass after each firing that brass is coming from somewhere.
The OP's brass is growing in length because the chamber is allowing the brass to expand outward and forward and he is then squeezing it down excessively.
This causes casehead separations and loss of brass life.
In your example your gun may need small base dies but if it doesn't you are also overworking your brass.
Yes you may be getting g 20 loads from a piece of brass but without small base dies you might get 59 reloads. We don't know because you only gave us part of the story.

[8185854610]

UPDATE I took 20 pieces of brass and measured them for overal length. They are lake city 556 2013 brass. Bought new have been fired twice. I set up redding small base dies with .002 shoulder set back. Process 10 pieces of brass which were exactly 1.755 in length. Lubed with imperial wax. And full sized them, the remeasured the average length increase was .006.
I repeated the same process with identical brass with lee std full length dies same shoulder set back. The average increase in length for the 10 cases was .005. The lee dies offer much less force.

[fguffey]

UPDATE I took 20 pieces of brass and measured them for overal length. They are lake city 556 2013 brass. Bought new have been fired twice. I set up redding small base dies with .002 shoulder set back. Process 10 pieces of brass which were exactly 1.755 in length. Lubed with imperial wax. And full sized them, the remeasured the average length increase was .006.
I repeated the same process with identical brass with lee std full length dies same shoulder set back. The average increase in length for the 10 cases was .005. The lee dies offer much less force

Less force? And that is it? I would think someone could find another 'therefore'. If I was interested in 'less force' I would use a force gage. And then there are gages that are not being used when making comparisons.

F. Guffey

[8185854610]

It was about 1/2 the pressure (pressure on my arm guage) on the press lever with the standard dies, and that's it. Get a gauge and duplicate the test and post the update, might be helpful?

[fguffey]

The sb die is not causing your cases to stretch. .

Because reloaders are conditioned to respond to words, groups of words and phrases it is impossible to separate stretch and flow. There was a time I would ask the question: "Is it stretch or flow or is it stretch and flow?" and that just made every reloader angry and it seemed they scorned the day they ever learned to read.

It makes no sense to me how a die can stretch a case. It is right up there with moving the shoulder: I ask "How do you do that?", no one has ever said; "I do not know".

F. Guffey

[fguffey]

It was about 1/2 the pressure (pressure on my arm guage) on the press lever with the standard dies, and that's it. Get a gauge and duplicate the test and post the update, might be helpful?

John Lewis, I understood every thing you said but I thought with all of the talent reloaders on this forum someone could add something to your conclusion. Something like: "This is what he discovered' therefore, etc. etc..

F. Guffey