Shorter than before

[Joel Chavez]

Well, as I mentioned earlier in the week, my son and I finally got to shot his Topper 158 chambered for a 30/30.:-D Last night I started to reload the same fire formed brass from this past weekend, but for some reason or another, the brass is shorter. I trimmed to 2.030 exactly. Now they are 2.000. What is going on here. I used 8.0gr of Unique with Rem 110gr Sp and Win brass, Federal large rifle primers seated at 2.400". What causes the brass to shrink? I was under the impression that brass would stretch when fired. Do I have to full length resize again to make it stretch and then retrim to proper size?:???: Thanks in advance. Later.

[OLPDon]

Just a guess:
When trimming cases the cut from trimming has chatter marks that are removed after the chambering and fireing of the round just a guess if the brass is new the lost of lenght is lost due to case hitting bolt face. It could also be when you reloaded the case there is stress seating and sizing.
Don

[44man]

Very simple, the chamber is large and the brass expands to fit it. As the sides are pushed out, the length gets shorter. It happens to all cases unless you shoot very high pressure magnum calibers that stretch the brass.

[9.3X62AL]

Joel--

I've had a few calibers recede SLIGHTLY upon firing, but never anything like .030". My first guess--and that's all it is--would be that radial expansion drew the case length inward. That was my thought when I saw it in other calibers (32 ACP and 380 ACP), low-pressure straightwall blow-back pistol rounds. I'm talking .002"-.003", though--nothing like you are seeing. When the cases I spoke of were resized, they wound up pretty close to previous sized length (.675").

In case you were wondering why I bothered with trim-and-check to blow-back pistol cases, the idea was to try getting the 32 ACP to get headspace on the case mouth instead of the semi-rim, the same bit done by the 38 Super enthusiasts with its semi-rim form to gain accuracy. It worked in the 32 ACP, but didn't make a bit of difference in the 380. FWIW, both calibers in W-W and R-P brass showed pretty significant length variation, from .672"-.681". Evening things up at .675" resulted in a 12%-15% case scrap rate due to underlength.

[Joel Chavez]

Well, all sound like great explanations. Here's what I also discovered. The OD and ID size of the neck are the same as before firing. :???: These are being shot out of a single shot Handi style rifle. Should I full length size the fired brass again to stretch them and then retrim? Thanks guys. Later.

[floodgate]

Joel:

All I can suggest is, try a few each way and compare them after firing (if you have or can borrow a good dial caliper); both length, and diameters just ahead of the rim, mid-way to shoulder, at shoulder and on the neck, and let us know how they compare. This could get interesting!

floodgate

[44man]

If the chamber is so large that it shrunk cases .030" I would not be full length sizing. I too think more measurements are in order to see where the problem is. That much expansion should be visible by just looking at the brass. There should be a bulge above the expansion ring.
If they are full length sized they won't be any longer then what you started with. You will sure over work the brass that can lead to early failure.

[grumpy one]

I have found that my 30-30 cases do not lengthen even with many firings if I stick to cast bullet target loads (17.5-18 grains SR4759 with a 175 grain GC bullet). However if I fire jacketed bullets at full pressure the cases get longer on each firing. I have not specifically tested what happens to case length at low pressures (i.e. when firing plain base 115 grain bullets with 8 grains of Universal) but I'm sure they do not get longer, and they may get shorter. This is with partial full-length resizing - FLS die backed off half to one turn, for all load types.

[Bret4207]

Happens to me with 32-20 brass after the first firing. Also watch for UNEVEN lengths. That'll screw with your head.

[Bass Ackward]

I never trim until after the second firing at high pressure if that is a capability of tyhe cartridge / gun combo. Otherwise, I have seen what you are experiencing.

What is the cause? Can be larger chamber dimensions as 44 suggests. It can be varying anneal on the cases too. Or it can still be in the dies though that is less likely I would think. That's why I also load so I can seat into the lands if possible and force expansion to occur .... evenly for lack of a better word.

If you full length re-size and trim and then fire again, won't this cause the same problem if chamber dimensions or dies are the culprit? I would just neck size and shoot again and see if things have stabilized. You can fire just three measuring before and after. If it is the chamber dimensions, then just don't trim until you fire twice in the future, and that is only if you have to.

[Joel Chavez]

Thanks guys. I'll be shootin' again today or tomorrow and give you folks a range report. Centex Bill loaned me his Lee soup can mold to try out, so I'm casting some today and loading them up with Unique. I just can't wait.:-D