Working up a new load, need advise

[BravoSherpa]

I'm working up a new load for my Rowland 460, it's a 155 grain hard cast bullet aimed at larger wildlife protection (also because I like to tinker). I've got some existing published load data for a 160 grain JHP that I can use a start, I can seat the bullet in such a way that the cartridge volume (water capacity in grains) is the same as the published data and the COL is within specs.

I'll certainly start with a very conservative charge (7.5 gr of True Blue I think). My question though is how do I find the upper limits? Should I keep increasing the load until I see case bulging or flattened primers? That idea makes me a bit nervous. I have a chrono and I'm guestimating a target velocity of 1100 fps, but I don't fully trust the readings from my chrono.

Thoughts or advice?

 

[FROGO207]

Welcome to THR
You do not really have to be that particular about case volume. I would just load it to the cannalure if it has one. Using the next heavier bullet weight data will give lower pressure and lower VEL round with your grain weight. Assuming you start at 10% below max you should be able to increase the propellant charge with your bullet weight to approximately the published VEL of the heavier bullet if no other pressure signs develop. This may be over the charge weight of the heavier bullet. That said I have found that for accuracy in a handgun the upper limit is not always the most accurate either. I usually work up a load with accuracy/function first and speed as a second indicator. When in doubt your best bet is to contact the propellant manufacturer and email them your bullet weight and caliber. They will usually suggest a usable load that will be safe.

 

[BravoSherpa]

Thanks

Thanks for the info Frog. I've been loading 10mm for awhile so I can definitely confirm that the high end loads are less accurate. I've never worked out my own load before because there's so much published data for 10mm. My main thought is for wildlife rounds, I can buy Rowland 255 gr hard cast loads for the bargain price of $2 per round, if you can even find them (I live in AK so delivery isn't an option). Obviously that's not very conducive to frequent practice at the range, that's one reason I hand load.

I went shooting last night with some rounds I loaded, 260 gr and 230 gr JHP. In all respects the 230 grain loads produced higher energy however they frequently stove-piped where as the 260 gr. loads did not. Not worried at all because I set my starting load below the minimum just to be safe so I'm pretty sure they were just short-cycling. What's interesting is that the 260 gr bullet is a LC and not an ACP round and thus the net volume behind the round is less. I'm thinking that the gasses expanding in this smaller are is why they cycled fine even though they produced lower calculated energy. That's my theory anyhow, I'm pushing my knowldge level of reloading and physics.

I did shoot some Buffalo Bore 255 gr rounds and for the record I'll say I enjoyed shooting those from my converted Springfield 1911. I got better accuracy and control then shooting 220 gr Buffalo Bore rounds from my G20