Case stretching (or lack of it)

[ChiefPilot]

I fired the first batch of .223 I made up over the weekend, and they worked great but the cases didn't seem to stretch at all. When I made them up, I needed to trim all of them and did so, getting them to about 1.250" +/- .004". I found that after running them through my AR, they were all ... 1.250" +/- .004". What gives?

Don't get me wrong - I'll be ecstatic if I don't need to trim & debur every time, but I expected at least some case growth.

The load BTW was 24.5gr of WC844 pulldown under a 55gr M193 projectile.

 

[RecoilRob]

Were you loading once fired military cases? If so, they normally need to be trimmed because the 5.56 Nato round is a bit longer than the .223.

Once you have them all trimmed, you shouldn't need to again for several firings if ever.

 

[Ol` Joe]

Did you measure them before or after the sizeing operation following fireing? Sizeing is what normally causes them to grow as you reduce the body and the brass flows foreward. I would expect a little lengthening, but you should see 4-5 fireings anyway without trimming. Chamber size plays a part also in how much stretch you`ll get.

 

[Sunray]

Case life is dependant on the load. Hot loads will stretch cases and otherwise wear them out faster than light target or moderate loads.
"...don't need to trim & debur every time..." You won't. It's not a bad idea to do a quick check after 4 or 5 firings, like Ol` Joe says, but you'll likely not see much stretching using your load. Mind you, you should work up a load for your rifle and not just pick one.

 

[ChiefPilot]

Thanks everyone for the help!

Were you loading once fired military cases? If so, they normally need to be trimmed because the 5.56 Nato round is a bit longer than the .223

Yes, they were mostly LC brass and I did need to trim almost all of them. One or two were already between 1.745" and 1.750", but the majority of them were well over 1.760".

Did you measure them before or after the sizeing operation following fireing? Sizeing is what normally causes them to grow as you reduce the body and the brass flows foreward.

I measured them after sizing, although next time I will do a before & after to see how much difference there is - thanks for the tip!

"...don't need to trim & debur every time..." You won't. It's not a bad idea to do a quick check after 4 or 5 firings, like Ol` Joe says, but you'll likely not see much stretching using your load. Mind you, you should work up a load for your rifle and not just pick one.

Excellent! I was hoping this was somewhat normal since trimming them got to be kind of old. About the load, I started with 24.5gr as a starting load and since it worked so well I decided to just stick with it. I don't have a chrono so I don't know what the muzzle velocity is, but it cycles my rifle reliably and is plenty accurate for plinking between 25 and 75 yards. I might work up to a "M193" load of 26gr at some point, but I'm just as happy to save powder, wear & tear on the rifle, and not have to resize as often using the lower power load.


Thanks!

 

[P0832177]

What dies are you using? You can get a carbide expander ball that helps with case lengthening during sizing operations. Make sure you lube inside the case neck so as to help with lengthening.