How much does the projectile effect load data?

[ricky1790]

New to reloading and wanted to know if 2 projectile the same weight but different styles have effects on the load data?

For instance I'm wanting to use a hornaday 165gr sst but the data I have is using a 165gr jacketed partition. Can I still use the hornaday round or no?

 

[cfullgraf]

Generally speaking, different bullets of the same construction and weight, you can use the same starting data and work up from there. So, for example, a lead core/copper jacket bullet from different manufacturers can share loading information. But it is best to research as much information that you can. Find as much data as you can for similar construction bullets. Start at the beginning data and work up from there.

Bullets of different construction, as an extreme example comparing a lead core/copper jacket bullet with a copper solid bullet, the data can be very different and it would not be wise to substitute one for another.

I would consider a partition bullet to be different enough from a lead core/copper jacket bullet that the data for the partition bullet should not be used.

Generally, the powder manufactures have lots of data on line. Bullet manufacturers tend to have printed manuals.

Just be careful.

 

[Texas10mm]

Why not purchase a Hornady manual?

 

[ricky1790]

Why not purchase a Hornady manual?

I have a hornaday manual but the powder i want to use(win748) isn't listed for that round and do to the powder shortage win 748 is all that I can find

 

[jmr40]

The Partition and SST are close enough. If you start somewhere around a mid range load and start working up you'll be fine. You may find the max load is somewhat different, maybe not. Both of those are basically old school cup and core bullets. The only time where load data might be vastly different is trying to load solid copper bullets with conventional bullet data.

There will be some difference as you approach max loads. For example a 180 gr round nose has a lot more bullet in contact with the barrel than a 180 gr pointed bullet. I'd use the same starting loads, but may reach a max load with the RN bullet with a lower powder charge.

 

[edwardware]

Good question. It matters a little, and less as the bullets become more similar; weight, length, shank length, jacket thickness, etc.

I use close-weight data without any issue, but I start low and keep excellent notes so I know each rifle's foibles, like early pressure signs.

 

[WestKentucky]

The main things to look at are bearing surfaces and bullet weight. Those two serve to resist bullet acceleration and can cause pressure changes which can be catastrophic, or conductive to bullet failure. Generally speaking, numbers will be pretty similar so you can substitute very similarly profiled bullets but only if they are of similar construction. I would not substitute a typical cup and core bullet for a copper solid for the same reason I don’t substitute 115gr data for 150 gr data in my .270. They are too dis-similar.

 

[ricky1790]

The main things to look at are bearing surfaces and bullet weight. Those two serve to resist bullet acceleration and can cause pressure changes which can be catastrophic, or conductive to bullet failure. Generally speaking, numbers will be pretty similar so you can substitute very similarly profiled bullets but only if they are of similar construction. I would not substitute a typical cup and core bullet for a copper solid for the same reason I don’t substitute 115gr data for 150 gr data in my .270. They are too dis-similar.

So are a sst and partition to dissimilar to load data? I notice the partition doesn't have a boattail and the sst does.

 

[Waterboy3313]

My advice is to do all the research you can and if you can not find published load data from a reliable source find the closet bullet data possible and work up from the lowest point. I generally start my work up about 10% lower and come up slow like .3gr increments until I'm in the ballpark.

Search for powder and bullet data on Google if you have to but I stick with reliable sources from the bullet and powder manufacturers only to get you started.

 

[AJC1]

Use a starting load and your good. If a book has a minimum and maximum, I would recommend never going below minimum. The 10% reduction is a common practice when one data set is provided it is maximum and please do reduce from that maximum. The reason for not reducing minimum loads below minimum is there is a possibility of explosion and rapid firearm disassembly. This phenomenon occurs with rifle powders normally in larger cases. The general rule is the closer to a full case the better. You may observe better averages in speed and pressure as well.

 

[Varminterror]

I would not blindly follow the Lyman data for the Nosler bullet, nor would I blindly assume transference of the Partition load data for the SST.

The Partition and the SST are exceptionally different bullets for profile and construction. The data isn’t terribly consistent between the Lyman, Nosler, and Hornady books - note the Varget max for the Nosler book is 2grn greater than that of the Hornady book. Oddly, none except Lyman list data for 748, and Hodgdon’s site doesn’t list 748 either for the 165’s. My Speer 13 lists 748 for 165 BTSP, Spitzer, and Grand Slam at 42.0-46.0grn, using a magnum primer (can’t say an older manual might run a little hotter than a more current manual). Hodgdon 2016 has 748 listed for a few bullets in 308 as DNR’s, but doesn’t have it listed for 165’s. The Berger manual has 748 listed for 168’s at 39.0-43.5grn. So no direct data, but enough to take your life into your own hands if you so choose. But don’t blindly assume one of these sources is an indicator that all bullets of that weight are equal.