JCN,

I always check all my cases for any signs of thinning using the same method as yours. So far they have performed well and the primer pockets are still tight(but not as tight as a new case).

Even though I always full-length resize, the die has been adjusted so it just "bumps" the shoulder back. When chambering a round I can feel a very slight resistance when closing the bolt.

I trim every time I reload the .375 because I always use bullets that need crimping. I trim the cases to 2.840 inches and usually trim off 0.003 to 0.005 every time. Does this amount case stretch seem excessive or is it normal?

When it comes to annealing, which method works better, using melted lead or using a blow-torch?

PS If you can't get Lee brand reloading equipment send me a PM and I'll mail you a lock stud and shell holder.
JCN

It sounds like you are doing everything right. That amount of case stretch is in the ball park. Check your length before and after resizing. If it is increasing from its trip over the expander ball you can polish the ball by chucking it in a drill and hitting it with some fine emory cloth. Just enough to make it look smoother, not so much as to decrease the diameter. Just mike it as you go.
The other thing I do is lube my case necks with a moly powder and steel ball bearing deal that NECO sells for about $39.00. That sounds steep but I processed over ten thousand cases before I had to order a refill of moly (about $12.00). That method really reduces drag over the expander ball for me. Unfortunately I don't know of anyone making carbide expander balls for any calibers above .338.
See if the need for trimming decreases if you back off on the velocity/pressure by about 100 fps.
Since the case slopes so much it will always stretch faster than cases with more of a shoulder.
I'm lazy, and only melt lead to make duck and goose decoy anchors. I do that outside, and only on days with a good breeze blowing. I've treated kids with lead poisoning before and don't care to spend time around the fumes. Color me a puss, but I don't really dig indoor ranges for the same reason.
Some posters on this forum told me some really good ways to anneal. I just did 1500 LC 7.62x51 cases with great results. Lee sells a cutter and lock stud combo (#90110) for $4.98, get one. Also get a 375 shellholder and case length gauge combo(#90164). Again the cost is $4.98. Take the shellholder and lock stud and attach them to a case. Chuck the assembly into a battery powered electric screwdriver or cordless drill. Then get a propane torch, light it and get the inner light blue flame about 1 to 1 & 1/4 inches long. Spin the case with the drill and put the middle of the neck so it is just touching the inner blue flame. Count one potato two potato, etc. until you count six seconds, then dunk the case into a pail of cold water. Don't let the case mouth get so hot that it glows red. A slight dirty orange almost glow is okay. The process goes a lot faster than it takes to read about it.
If your cases are stretching a full .005" each time I would pitch them after 8 firings with an anneal at #4 or #5. If they are only stretching .003" I would anneal at #5, and dump them after 10 loadings. By then your cost for the cases is down to less than 5 cents for each firing. That is good economy. Trying to make them last any longer is likely false economy.
Try Reloader 15 in your 375 H&H. You will be happy you did.
JCN

Basically, there's no particular difference between the .375 H&H and any other belted magnum case as regards case life, etc., between full-lentgth sizing vs neck-only sizing. How long a case lasts depends on how much the brass is worked. The more it is worked in reloading, the faster it wears out. The tighter or closer to minimum specs your chamber is, the longer your brass is going to last because it is not worked as radically when reloaded. This is NOT a caliber-dependent factor!!

Somewhere I read that there is a varnish or indicating paint that is available that changes color at the proper anealing timperature. You paint this stuff on the necks of your cases and fire them up. When it changes color just drop them in the water. Done to the right temp every time. "D"

It's called Tempilac. You can get it at welding stores. Use the 475 degree stuff, and just put a dab on the shoulder. Once you get your timing down you can go on time and appearance. I believe the Hornady kit also has temperature indicating paint. A lot depends on wether you are doing 15 or 150 or 1500 cases. By the time I got to the bottom of the bucket my technique had improved a lot, but the first ones were just fine also.
JCN
There was a thread a few weeks ago on this topic and I believe it was Steve Ricciardelli who posted a link to a web page that gave chapter and verse on annealing.

Do yourself a favour and get the Lee collet resizing die and say goodbye to lubes, case stretching and head seperations. I started out using a "quality" bench rest die set that buggered up the headspace no matter what I did. If I was lucky I got five reloads out of a case. With the collet die not only do the cases last practicaly for ever but I get better ammo too and it requires very little effort to resize. Also, you can adjust the amount of sizing you need so you can forget about wasting money on those dies that use bushings. Collet dies are cheap and come with a "if it doesn't load better ammo we will refund your money" guarentee.

I anneal the case necks about once every twenty reloads whether they need it or not.