Ok I have the common lee cutting tool and a shell gauge small rod. I typically use a drill and the shell guage just stops the cutting as the length of the rod. Ok my gun likes about .005 to .010 more off. Otherwise the very top of the case lodges slightly...nothing that won't extract or anything but it's a single shot rifle and I can feel it pulling a little harder with the extractor when pulling shells out on breaking the barrel open.

How else can I trim these casings a tad more without the gauge rod?

I'd like to be able to trim some casings that I don't have length guage rod for as well.

One option is to stone down the tip of that rod on the trimmer you have. Go slowly and measure carefully until you get the length you want.
There are other types of trimmers that adjust to length instead of having a fixed limit like the Lee.

As boxer noted, you can decrease the trimmed length by finely trimming the rod. If you need to increase the length, spread the split shank of the cutter ever so slightly with a slotted screwdriver blade and then set the trim length with a caliper. You will need to thread the cutter in with pliers so take care to pad the cutter or tool. I use bowstring nock plier, works like a champ.

I also have a couple of cartridges that have special length needs. I just ordered a cutter from Lee for the appropriate length.

Are you sure that its the trim length that is causing it? Are these cases that you have full length resized? I would assume your not bumping the shoulder back far enough before the trim length is too long, its a pretty common problem with new reloaders, happened to me as well as many others on here.

http://www.midwayusa.com/product/269638/forster-original-case-trimmer


Trim any case, up to 300 Win Mag, to any length you please.

this was it...I realoded my first set of used brass with a collet resizer. I went ahead and did a full length resizer after, and will now use a collet after. Now the casing is formed to my rifle, and the collet will just resize the part that matters.