I'm not a complete dummy, working on it though...but seriously, I will soon be loading 44 mag using Alliant 2400 and 240 JSP bullets. Awhile back I took a look at Alliant's load data for 2400 and 240 gr bullets and saw that they used Speer GDHP, which I guess is Gold Dot Hollow Points.
My bullets are from Northeast Reloading and they are jacketed soft points, and also 240 gr. Does this matter? Load data as I understand is often brand specific and deviation is a no-no? But 240=240?
Yeah, me too, a grain is a grain. But now that I'm actually reading up on stuff...directions? Who needs directions?
I sent an email to Alliant, and they got right back but only discussed chamber pressure; that whether shooting a rifle or revolver the load data is tied to allowable chamber pressure. I asked Northeast too, but have not heard back.
Christmas yesterday, got a bench mount for Lee stuff and a Thumler tumbler from Cabela's
Most rifle loading tables / data I use are specific to caliber, powder, bullet weight, and speed. I can only make an educated guess that minor bullet variations would affect accuracy and performance but that's where load development begins.
You most likely won't notice a difference, but this is one reason why you start low, and work up.
If the bullet weight is the same, but the profile of the bullet is different, the bearing surface will be different. That will more or less drag in the barrel, and can change the pressure curve.
Personally, I try to find load data that is at least the same type of bullet to compare, and failing that, I use what ever data I can find with the same weight, and work up from there.
I have never had a problem, or any over pressure signs at the starting loads, no matter what bullet type the data was for as long as the weight of the bullet was the same.
I have had high pressure signs before the max load when using different bullets than the load data was tested with. Nothing insane, but primers that were flatter than I liked, and such.
A variable to consider in addition to bearing surface, in this example, is the amount of available powder capacity with the bullets seated to the same OAL. In this case when using a 240JSP bullet, which should be shorter than the 240GDHP in the load data, will give you more "room" for powder in the case. This should reduce pressure. I would feel comfortable with doing that. The other way around: reducing powder capacity with a longer bullet of the same weight, and an increased bearing surface may be problematic, specifically with faster powders.
I make the assumption that the published load data is a set of data that will give me a safe maximum and minimum load, with conservative safety factors applied. My job is to use the data to develop a load that works well for my application - whatever balance of power and accuracy I want.
If I stay within the published max and min, and use a similar bullet (weight, material, jacket, etc.) I shouldn't have any unsafe pressure issues.
For your application, look at the OAL from 2 perspectives: external as is stated in the load data, and then what that OAL gives you inside the case with the bullet you want to use, vs the one specified in the data. If you are using this same OAL, with different bullets of the same weight, that is changing the depth that the bullet site within the case.
The more room the base of the bullet takes up within the case, compared to published data, the higher the pressure will be compared to published data.
Gotcha. I've a 77/44 that I'm going to use out back for deer, and settled on jsp ammo. The 240 winchester white box stuff is going, here anyway, for about 34s buck a box; seems to get good reviews. But I have empty brass and powder so for the price of the bullets I'll just roll my own. Good excuse to get the reloading gear I didn't have. Probably been 15 years since I last reloaded anything. Appreciate the help.
It looks like it would be the same in yoir case but the pressure can be alot more or a lot less when dealing with bullets of differnt construction even in the dame weight. Od diameter of the bullet, monolitic or hsrder thicker jackets csn increase the force needed to conform/swag the bullet to the bore so even with the same weight if one is dealing with hot loads is better to come down in charge and then build it up again looking for signs of excessive pressure.
Better come down and work on the load than being sorry due to rushing hot loads.