Home Forums Reloading Big Game Rifles Riddle me this, max book load discrepancy

For the 6.5 Swedish, H4350 and a 120gr GMX bullet, Hornady lists 43.7 gr as max. But look at the Barnes 127gr LRX data and they list 37.7 gr as max of H4350. That’s a big discrepancy in powder for a small difference in bullet. Why the hell are there such differences in reloading manuals? I understand that there are vast differences in firearms used, yet it seems to me the max thresholds should be very simple… The SAAMI specifications for each cartridge state a max pressure tolerance, right? So given that, isn’t that max pressure figure largely what Max loads should be based off of? So why the discrepancies? As a somewhat new reloader, I find the alchemy of it all rather frustrating! For such a potentially dangerous activity, you’d think there would be more uniformity across the board with different loading manuals. There has to be a better way of communicating this information. Or am I missing something?

Bearing surface and composition of jackets. The dangerous part of reloading is digging up max loads of one maker and using that for another makers goods. Ignore that you might be missing something.

Like was said the Barnes are made differently and the materiel is not the same.

If you are looking for a consensus look for bullets made the same way.

Cup/Core versus solid.

Totally understand that, but it still doesn’t make a 6 gr discrepancy make sense. 1 maybe 2 gr difference is logical.

I know. That’s exactly what I did. Both bullets are monos.

Mono's of different material. Different Barrels, cases, primers and powder lots. Lots of variables, that's why we work up in our own rifles to get to our rifles max.

The Hornady manual shows 2800 fps at that max charge level. What velocity is the Barnes manual showing at their max powder charge? Before proceeding with the rest of my thought here I'd need to know if they are close.

Of course, and I do that too. But my point is, if there’s a uniform SAAMI max pressure per cartridge, why isn’t there a corresponding powder max and bullet combo listing that is even remotely close to uniform? It would not be hard to reverse engineer and come up with better data to eliminate at least some of the guesswork.

2595 FPS with max charge of same powder and 127 LRX, hence my point. That’s a massive change in velocity for relatively minor differences in bullet weight, size and construction. I’d expect some FPS difference given they are different bullets, but not 200+! That’s illogical. Assuming same components, Max should be close to max, across the board, and I’m finding that’s not the case! The Swede is just one example. I see it too in other cartridges.

In the particular case of the Swede you're also dealing with lots of differences in throats and even chamber dimensions. SAAMI max is 45,000 psi and one assumes that Hornady and Barnes have loaded to that max, so the logical assumption is that the Barnes bullet produces a lot more pressure than the Hornady. They could only reach 2595 fps at 45 kpsi while Hornady could reach 2800 as that same pressure although you've probably already surmised that.

Multiple magazine articles and book chapters have been devoted to answering your original question so I doubt anyone can supply you with an answer that can be encapsulated in a forum post. As others have noted, not just weight but bearing surface and hardness of the bullet can cause great changes in pressure from one bullet make/model to the next. Throw in differences in pressure barrels from one company to the next, maybe even different methods of pressure testing, different brands of cases of differing internal capacity, primers of different brisance, on and on, and it's a wonder when two companies come close to agreeing on the same powder charge producing the same velocities with the same weight bullets. A six grain difference is fairly large but it's not unheard of, while up to a 3-4 grain difference between manuals even using standard cup and core bullets is not rare at all.

Getting back to the specific example of the Swede. A modern rifle should be capable of handling pressures of 60 kpsi so there is a way to safely maximize the velocity for a company's bullet, and that's by looking at their data for the .260 Remington. Using the same bullet and powder you can assume that the Swede can get the same velocity as the .260 at pretty near the same pressure, although it might take a couple-three more grains of that powder over what's listed for the .260 to get there. You can actually surpass the .260 velocities but only by about 30-50 fps and you're in uncharted waters there so it's best to stay at .260 velocities which are plenty enough already. Plus, and this is the biggest selling point, with the Swede's larger capacity if you match the .260's velocity then you know you're in safe territory pressure wise.

Again, there are so many variables between loading manuals that they will rarely agree exactly even if both load to the same max pressure and there is almost no way for the average home handloader to extrapolate or interpolate from one company's data to another. I know it's frustrating but that's just the way it is.

Good answer. Thanks.

As Jim said, lots of variables and you probably won't see that much difference in a modern cartridge. Check the manuals, one may say their loads do not go over the 45k pressure while the other has a disclaimer that the data is for modern rifles only.

That's something I really wish manuals would do - list the actual pressure they load to. Some will specify that, the Speer manual has good detailed info about that in their write up for the Swede* and some other cartridges, and so does a lot of data in the Lyman books. One assumes load data publishers will go up to SAAMI published standards but I dislike assumptions unless they are as well founded as possible, if someone has definite info then it would be nice to explicitly state it.


* Seems I was wrong about 45,000 psi. Speer says 45,000 cup (crusher) but 51,000 psi (transducer). The SAAMI table I looked at online showed the 45,000 number as psi. Not a huge deal, but since we're discussing specifics it would seem remiss not to mention it.

Yes, the pressure max that they actually loaded to would be very helpful information. I actually called Barnes and asked this question and got a similar response, about all of the numerous variables involved. He said that Swede data was loaded to 51k.

To further muddy the waters if you look at the H4350 max data for the .260 Rem, same bullet, it lists 42.8gr and 2793 FPS. Again, such a large difference that seemingly defies logic. That .260 data seems more reasonable than the Swede data, at least in a modern rifle. For comparison, I should have asked the Barnes guy what pressure figure the .260 was loaded to. Evidently a lot more.

Hornady has some oddities and inconsistencies when it comes to max velocities. Latest Hornady manual I have is the older 7th Edition but for 6.5x55 loads the only test rifle is a 1896 military mauser with a 29" barrel. ?!?!? Really? Same book gives 3 different max loads for the 45-70 depending on trap door, Marlin lever or Ruger #1. That puts the old "never can tell what rifle that there hot load might end up in" argument in the shade. .270 Weatherby Mag 26" barrel 130 grain Interlock, SST or Interbond gets over 3200 but less than 3300 due to their weird way of blocking velocities. So just over 3200 fps with a 130gr Interlock & SST with a 26" barrel when the Interlock is supposedly one of the faster bullets to load? That ain't much over what some folks get with the .270 Gay when you're talking 26" barrel. Other examples there if you search. Personally don't have any confidence in how Hornady comes up with some of their data.

Hornady No 10 still has info for the 29 inch barrel and states it will be 200fps or so faster than most sporter barrels. The Barnes manual uses a 24 inch barrel.

That isn’t what it says at all. It states that velocities from 29” and 24” barrels will both produce 200 fps faster velocities than the 18” carbine barrels.

To the OP: I don’t have a current Barnes manual, but No. 3 lists a max load with the 120-grain XFB as 47.0 grains of H4350 for 3011 fps. That’s from a 24” barrel. I have no answer to your original question, other than a misprint/typo. That happens all too often with most reloading manuals, sadly.

This topic comes up regularly in all reloading forums, and the potential answers remain the same.