Ok. This is freaking me out a little. I'm about 99% sure it's not a real big deal, but it still bugs me as I don't fully understand the mechanics behind what's going on.

I have a Remington 700VS in .308 Winchester. For the last year, I've been using Winchester commercial brass. I'd F/l size every 3-4 firings, and neck size otherwise. Trimming was done as needed, and the last time I trimmed them (~7 firings) they had quite a healthy bit of growth since the last trimming (~3 firings earlier).

I switched to Lapua brass, and trimmed all my cases to 2.005" using a Wilson trimmer, so I'm pretty damn sure that they were at 2.005", period.

After the inital firing, I think I happened to measure one or two cases and noticed they were down to something like 2.004 or 2.003. Little bit o' shrinkage during fire forming, no big deal...

Now, after 4 firings, neck sizing only (Redding Type 'S' bushing die, w/ .337 bushing), I'm measuring the OAL of the cases before sizing them. What is bizarre (in my mind) is that the cases are all measuring btwn 1.998-2.000". So the cases have shrunk 5-7 thou in 4 firings. I've heard of some shrinkage in fireforming of short BR cartridges, or cases w/ minimal taper and sharp shoulders (Ackley). But a .308 Win w/ a relatively relaxed shoulder and body taper angle doesn't seem like it should be shrinking that much.

Comments, suggestions?

Monte

How much have your cases expanded over their original size in diameter? The cases expand to fill the chamber when fire formed and the brass has to come from some where. They shorten a bit with each fireing until they reach a size that truely fits the chamber. Full sizeing them will chrush them back down and cause them to lenghten again. The Redding neck sizer you are useing only sizes the neck displacing much less brass. Think of this as a good thing. The less you trim the less you have to worry about cases separating- wearing out.

To see this occure dramaticly try measureing a new 45acp case and fireing it. Then remeasure. I`ve got cases that have shrunk ~.010" and have been fired and full sized 7 / 8X. I loose them before I ever get them back up to where I need to trim.

If you FL size them they will get long again! For most of us that use expanding buttons the necks get stretched and require trimming.

As you fire those cases the base and bodies expand and are pulling the metal out of the necks.

Well, I knew the brass had to be going *somewhere*, just where was the question (and that much of it!). The web of the case miked at 0.4685 new and 0.4707-0.4711 after 4 firings, so, I guess some of it is down there, and in the shoulder area?

As far as F/L sizing, well, from this point on I'm going to pretty much *have* to F/L size (Redding Type 'S' F/L die, or a Redding Body die and some form of neck die), to ensure flawless chambering (using it as a NRA HighPower match rifle, and need to be able to count on it during the Rapid Fire strings). Only a small amount, perhaps 0.001-0.002 or so, but still F/L sizing. So it sounds as if my cases will start growing a bit here once I start the F/L sizing regimen. Wonderful. Ah, well. That's what I got the Gracey for

Thanks,

Monte

I had the same problem with my 22-250 fired in Rem 700 vs. After resizing, I placed the brass on a tray in front of the TV during Baywatch. This seem to cure it !
Seriously, I have the same deal. I did notice that I have to "really" full length resize brass or I have a slight tightness in bolt closing. I can take a fired piece of brass and close without any bind. A resized one snugs a little. Yes I do lube case mouth Etc. Go figure. Gun shoots 1/4 moa. ?????????????
Tacksmacker

You didn't wash them in hot water then force dry them with heat, did you?
I did that with a pair of favorite wool socks and turned them into baby booties. Been a bit skittish ever since.
Jim