Case Length - How Important In Single Shot Pistol?

[Fred McIntire]

I have a Thompson / Center Encore Pistol in 7mm-08 caliber. I am reloading 140 grain Nosler Ballistic Tips over 40 grains of Varget with a large rifle primer.

The maximum case length is supposed to be 2.035". Some of the cases are measuring up to 2.050" in length.

Is this going to create a hazardous pressure if they are not trimmed? Will there be a problem extracting the fired cases? I do not have a case trimmer as of yet; however, I can see that I really need to invest in one.

Also, how do I determine, or what is, the optimum overall cartridge length for this caliber. What do factory loads measure overall length?

Thanks for the info,

Fred

 

[Dan in Va]

One way is to make a chamber casting with Cerrosafe.

The other is to get a very simple (and inexpensive) tool from Sinclair, and they come individually in all the popular calibers. It's a steel and lead alloy plug that fits in the case neck and will come to a stop when closed on the chamber. You'll need to sacrifice one case and trim the neck about 0.120" short and partial neck size enough to give enough friction so the plug won't slide too easily. Then you measure the overall length with a dial caliper. It might be called a Chamber Length Gauge.

I was a surprised to see that some of my factory chambers were cut about 0.025" longer than the loading manuals listed for max case length.

Hope this helps.

dan

 

[Ol` Joe]

Yes, :shock: if your chamber lenght is less then the lenght of your case the result could be dangerous. Loading cases that excede the SAAMI max with out knowing exactly how long the chamber is is not a good idea. Dan offered a couple of ways to find the "true" lenght of your chamber but the easiest way is just keep the cases trimmed to the recommended lenght. The manufactures cut chambers a tad long as a way of avoiding liability issues but it isn`t a excuse for ignoring steps in our loading that ensure our safty.