Please explain bullet manufacturer reload data

[longwinters]

I am reloading/shooting Hornady and Nosler bullets.  Bullet weight is 150gns and in this case is for the 308.  Here is the question.  Hornady lists different powder quantities for each style of bullet (even in the same weight bullet for same caliber).  Yet Nosler quotes powder amounts generically for all bullets in the same weight class for any specific caliber.  Hornady also lists their velocities much lower as well as the quantity of powder recommended.  Can you tell me why 2 different companies are so different in their data and what do you do in this type situation when trying to compare bullets/loads/velocities etc?  

long

[New Hampshire]

Chalk it up to a number of things.  First, Different test beds.  Some use actual guns some universal recivers.  As you probably know, what might show signs of normal pressure in one gun could show signs of high pressure in another.  Second, Cases used could be different.  Different capacity means different results.  And third, each manufacturers bullet is not made the same as another.  One bullet jacket could be harder, the other softer.  Thats why specific components are listed in the manual.  The data can be used as generic, but you need to follow the safe steps by working up and checking for pressure signs.
Brian M.

[Siskiyou]

Each gun is an individual, and I am sure the legal staff also has a say in what the companies publish.  One of my later Speer Manuals recommends destroying older(pre-lawyer) manuals.

In my younger days I developed a load for my Rem.760 in .270 Win.  It was close to max.  I had a couple of hundred rounds loaded up.  I went away from home for a summer job.  I noticed on return that I was short a few rounds.  My brother tried my ammo in his Rem 760 of later manufacture.  My loads were to hot for his rifle and he had extraction problems.  It could not have worked out better then if I had planned it.

[Bullseye]

I am really confused by a lot of this too.  The new Hornady manuals show loads where the max is 3-4 grains lighter than the old books in some cases.  I have shot some of those old heavy loads for years, what do I do now?  Are those unsafe and I was lucky?  Should I keep shooting them because I have never had signs of high pressure?

My latest dilemma is with a 45-70 Contender barrel.  The old Hornady book and the Seirra book show Contender loads that are in the lever action area.  The new Hornady book list the Contender as Trapdoor levels.  I have read many articles in which they give Contender 45-70 loads and they are on the upper end or higher of the lever action load.  Makes it very confusing.  I called T/C and they say to use trapdoor loads and no higher.  So how have all these people kept from blowing guns up all these years with the hot 45-70 loads?

Wish I had the answers, but the more research I do, the more confused I get.  As far as the 45-70 Contender, trapdoor loads are all I want to handle anyway, so that is what I will use.

[Questor]

They all use different methodologies. I like Speer's best because they give the exact OAL for each load and they use real guns with factory barrels in common configurations. Consequently, their data is most similar to reality.  Lyman's information is practically useless if you're shopping for a particular velocity. It's only good because the loads are known to be safe.

[Iowegan]

I got a new Speer #13 for Christmas. I compared my favorite loads from my old Speer #11 and they were "off the charts" in the new manual. If you haven't noticed, new factory ammo in many cartridges is loaded a lot weaker too.

I have a friend that used to work with me in the DOJ lab many years ago. He is now an advisor to the Small Arms and Ammunition Manufacturers Institute (SAAMI). I talked to him about the reduced loads and he said the liability issues have forced American manufacturers to light load. I suspect the reloading manuals have done the same thing because they also suscribe to SAAMI specs and don't like law suites either.

I see no reason why the "old" loads wouldn't work just as good as they did before the manual was printed. There are a few powders where formulas have been changed, such as Unique. Don't know if it makes any difference on the burn rate or not.

[New Hampshire]

.....and if you ever needed a reason to start handloading, this is it.  
Brian M.

[The Shrink]

There are a couple of other reasons not yet noted.  Altitude of the testing site is one, when Sierra moved from sea level southern California to the mountians their data showed the change.  Another current issue, and perhaps the major one today, is the recent advent of strain guages.  Prior to this it was very expensive and questionably accurate to measure pressure in the chamber.  Some of that data was extrapolated, and now that strain guages are used they are backing off some of those extrapolations.  

It's not that the old loads were "unsafe" in the guns that regurlarly and safely fired them.  It's that the gun that gets by with a tight chamber or throat may not handle them well, and no company (especially firearms companies and related) wants unhappy customers, or perhaps rather thay would prefer more unhappy customers with intact firearms rather than a few unhappy customers with less than intact firearms.  

Yeah, lawyers cause extreme statements, but there are real causes underlying those lawyer caused statements in very many cases.  

Wayne the Shrink