I’m developing some loads for my drilling in 7x57R. Normally I’m taking it slow with very safe loads, but I’m making some FMJ-loads for my upland ptarmigan hunting, and would like it as fast as I can. But I suddenly realized, I do not have a qlue about pressure signs on these guns. Headspace is normally large, so the primer reading are mostly worthless. No extractor marks etc etc. Does anyone with experience on double rifles, or other break barrel guns have som input for me?

Working up loads for a double or break action with regards to pressure signs is certainly different than with a bolt gun where primer appearance, head stamp damage, etc can be observed, mainly due to the much lower pressures these guns operate at.

This is certainly not a definitive statement but is the best advice on the matter I've been given, other than closely following published load data.

After firing the rifle, slowly open the action but only just, and avoid activating the extractors. Point the muzzles upward and the brass should fall out of the chamber. If it doesn't a light rap on the barrel near the action with the heel of the hand should cause the brass to fall. If it doesn't, and remains in the chamber, start suspecting excess pressure.

Thank you, that acctually make sence.

Since you do not have a "clue", have you considered buying one of the virtual ballistic software programs such as QuickLOAD? I have found the software I purchased to a significant asset.

I have quickload. And calibrated after chronographed loads, it is absolutely excellent, and seems to be close to spot-on with the simulations. But when it comes to very fast powders for the calibers, I just don't trust the pressure data simulated.

I've loaded some 40 grs hornet bullets to 2400 fps for my .22-250 with shotgun powder (Lovex S035). During this project i got some extractor marks when I reached 2600 fps. However, Quickload (calibrated the Ba from chrono data) tell me I've reached a max pressure for this load is 19000 psi. So I have a feeling that quickload does not manage to calculate the pressure spike with this fast burning powder, because the pressure signs are there. S035 is in the burn velocity around Green Dot.