I've used both of these powders for 15 or 16 years. I've always heard the warning about not using reduced loads with either powder. I always stick with published data. My question is why the data from Hodgdon (as well as Winchester data before W296 being Hodgdon) show one minimum charge yet Sierra shows a minimum charge well below their data.

As an example for 454 Casull with their 300 gr JSP Winchester shows 29.5gr of W296 as a minimum. Hodgdon shows a 28.5gr minimum with H110 for a FA JFP. Both charges are fairly close in weight. Sierra shows a minimum of 24.1gr of H110 and 24.8gr of W296 as minimums for their 300 gr JSP.

I know they're using different bullets but the max charges shown in data for all three bullets is very close. For max charges there's 1gr difference for H110 and 1.5gr difference for W296 when comparing Hodgdon/Win data to Sierra data. Their max data is within 3-5% of the Sierra max data. With max charges that close I wouldn't think the minimum charge listed by Sierra is due to a bullet that seats deeper or is harder resulting in higher pressures.

Hodgdon data says not to go more than 3% below the minimum H110 charge listed. Winchester data says not to go below minimum charges shown for W296. The minimum powder charge in Sierras data is 15.5-16% below H110 and W296 data. The min to max spread Winchester lists for W296 is 2 gr. Hodgdon data shows H110 has a 1.5gr range between min and max charges. Sierra data has a 5.2gr spread for W296 and a 5.1gr range for H110 from min to max.

This discrepancy in data is something that's always confused me but I didn't think about it much before. I'm only asking now because I'd like to try the lower end Sierra loads. Sierra's lower velocity load is appealing to me due to issues with my hand. I have a good supply of the 300 gr Sierra JSPs and W296 and I'd like to use that combo. I just keep questioning the Sierra data since its so much lower than Hodgdon and Winchesters data. Anybody know the reason for this?

I don't know the why, but I have seen similar numbers with the 45 Colt. I have some 240 grain JHC's and just wanted to see what Sierra had for "Ruger only" data. Sierra's maximum load is more than 2 grains lower than Hodgdon's starting load, and Sierra's starting load is 6 grains less than Hodgdon's. I have also seen similar with Hornady compared to Hodgdon, with max loads from the bullet maker being less than min loads from the powder maker. I don't get it either.

Glad I'm not the only one! With most powders I wouldn't be too concerned. All I've heard since I started loading H110 & W296 is don't load below the minimum listed in their data. Having published data loads that are all over the place kind of defeats the purpose of the rule to "only use loads from published data".

I wonder if they use slightly different testing procedures that give them different results? For instance, would using a fixed pressure barrel give different results from testing with an actual firearm?

Maybe go with the bullet manuel for the bullet you are using.Sierra for Sierra Hornady for Hornady.They have the pressure equiptment for testing pressure and most use only there own bullet.Sierra has always been very helpful when I have a question so a call to them or Hornady may help.Most reloading books will tell you that there loads are safe in there guns and there data was safe on the day they tested. But the loads are GUIDELINES and not written in stone. But you will find an occasional load that they no longer recomend so the safe bet is to call them and ask. Go slow, Check often.

Well, I know Hodgdon's and Accurate have pressure testing equipment because they provide those numbers in their data. Neither Sierra nor Hornady provide pressure measurements in their books. I just believe the powder makers have more confidence in their product than the bullet makers do and the bullet makers err on the side of conservatism. I put my faith in the powder makers, but I like to reference bullet maker's data when possible. On all occasions bullet makers numbers have been lighter. But does that make them right? I don't know.

I am looking at Sierras data for Sierras bullet. I cross reference data whenever possible too. Powder manufacturers like Hodgdon/Winchester also pressure test loads. They're also most likely to know intricacies of their powders. When they say not to reduce their load data with a specific powder there's a reason for it. That's why I was curious about data showing loads 15.5-16% below what they say can be used with that powder.

There's often a reason data changes. Its not always a change in powder charge weight, primer or a bullet/seating depth, etc. Its not always a case of "go slow, check often". As an example Lyman started adding a footnote to use a case filler over light charges of fast powders like 2400 in large cases like 45-70. The data itself didn't change. It had nothing to do with working up loads and looking for signs of excessive pressure. The reason for that footnote is there were instances of detonation when the powder had settled against the bullet.

Through people asking questions and communicating the reason for detonation was discovered. As a result, a lot of people were aware of it before Lyman added that footnote to their data. By researching .45-70 loads I became aware of it long before that data change. You'll still see data that doesn't call for a case filler using those powders in large cases.

Detonation might be a rare occurrence but I don't want to have a gun destroyed or worse because I didn't try to educate myself. By cross referencing data and noticing when there's a significant discrepancy, hopefully I'll avoid being a statistic that causes a company to realize there's something wrong with their data.