Working with 7-08 brass. Max length is listed as 2.035. I've been told a trim length should be 2.025. Is it OK to keep loading fired brass as long as it is still under the 2.035? I was assuming the 2.025 trim length was specified so brass wouldn't have to be trimmed every time it was fired but didn't know if there was still a safety margin based on instrument accuracy built into the 2.035 measurement. For example,since I'm using a cheap Harbor Freight caliper, should I trim at 2.033 or 2.034?

The 2.035 length is the maximum you should let it grow but even that has a fudge factor built in. If you did a chamber cast you'd see the neck section probably allows for 2.045 or even 2.050" case length. Don't quote me on that but the few factory chambers I've cast and measured all allowed at least another hundredth or two breathing room. Unless you're a masochist and just love trimming , you can wait until they all get to be around 2.035 or even a couple-three thousandths over that and then trim them all back to 2.025". And don't worry if you trim them back to 2.022 or 2.023, that won't hurt anything either.

I recently messed up with some .25-06 brass that has a max case length of 2.494" and a trim-to length of 2.484" I neck size which helps reduce case stretching a lot so I forgot to keep track of this particular batch. When I finally measured them they were all at 2.510" or thereabouts and some were even 2.515", but they still chambered and fired cases did not show the pinched necks which is the tell tale sign that your cases have grown too long.

Anyway, definitely not recommending someone let their cases grow like that. Best practice is to trim them before they go over that max case length, but just to say that in a factory chamber there is no major catastrophe waiting to happen if your cases are a couple thousandths either way of the max recommended case length.

Thanks a bunch Jim.

I just trim after I hit max.

You can also invest in sinclair chamber length gauges.

Easy fix...make a dummy round trimed to the desired length,so you can set up the trimmer quick but accuratly, and trim after each sizing. Make a habit of it, as you will find some pieces will grow faster than others. This habit contributes to uniformity and accuracy of the finished product.

I have one of these for almost every caliber I load for and I guarantee you they are a great, small investment that saves tons of time!

https://youtu.be/JKnXJxaAw2U

For hunting rounds Jim nailed it. The bench rest crowd may be a lot pickier but they are slightly crazy already.