Thread: GRT users.

A couple of questions from someone new to using this.
Firstly, there doesn't seem to be an option for selecting a primer type? Is there? have I missed it?
Second, what maximum working pressure would you recommend for a modern bolt action rifle?
Thanks in advance to anyone who can offer some suggestions on this.

When you select the cartridge you are loading for GRT will give you the max pressure - with mine when I select 223 it gives me the SAAMI maximum. With other cartridges it doesn't specify who set the max but they're both a touch over 60,000psi.

GRT doesn't have an input for primers by brand - it only differentiates between 'standard' and 'magnum'. It is part of the 'Initial pressure' function. Press the gold star on the Initial pressure line and you can input what type of primer and also bullet type - it differentiates jacketed, lead and monolithic copper from memory

For maximum “modern bolt action pressure” I would use the CIP or SAAMI spec as bolt thrust is related to the taper of the case.

Another question. Does "barrel length" refer to what the factory call it or the length of rifling?

Originally Posted by Shearer

Another question. Does "barrel length" refer to what the factory call it or the length of rifling?

Barrel length is what I believe it means, total barrel length at least thats what I use.

Originally Posted by Shearer

Another question. Does "barrel length" refer to what the factory call it or the length of rifling?

It’s measured from the bolt face (when closed) to the crown.

Can you use GRT on your phone or PC only?

Originally Posted by Trav-6mmrem

Can you use GRT on your phone or PC only?

PC only as far as I'm aware.

For those who haven't heard of GRT, it is a free internal ballistics software programme. It is named after Gordon (Gordon's Reloading Tool) who unfortunately passed away last year. Last time I checked it was still able to be downloaded for free. As to what is happening with it in the future I'm not sure - there's some discussion boards for the tech minded. Anyone have any further information?

I've been using it for a year or more now and like it.
For the 3 cartridges I have used it for the p-max is set and it tells you how close you are.

One interesting thing, I load 358win, and using the same powder the Nosler 200gr accubond (White tip) hits pressure at approx 2 gr less powder than the Sierra 225gr gameking.
Due to the thicker harder jacket raising starting pressure into the rifling.
Z