A Man with Two Reloading Manuals Just Gets Confused or Not :)

[GRingle]

Help me out please. I am perplexed. I am reloading 7 mm Mag. I have Hornady 139 SST projectiles and H-4831 powder. My thought is with Hornady rounds I use Horandy data. With that said in a 7 mm Mag, 139 gr SST, and H4831 then the starting load would be 55.5 gr with max load at 65.0 gr. I have also been told to have 2 manuals. So when I check the Lyman book for a 140 gr projectile and the same powder then I see starting loads of 62.0 gr with max at 67.5 gr. And to confuse myself even more I jump onto the Hogden web site reloading center and they list the starting load at 64.5 gr with max load at 68.8 gr. I am probably making a wrong assumption but why would this be so different between the load data. Could it be their test rigs used? While I feel comfortable to use the Horandy data I am concerned about the large ranges seen in this example on the loading data. I know starting low and slowly working up watching for pressure is the right way I am concerned about too low a starting load. Thoughts please.

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[Greenbug]

I'd start in the middle of the range at about 61.0 grains. Load 3 rounds of 61, 62, 63, 64, 65, 66, 67 and 67 grains shoot them and inspect closely for pressure signs like cratered or flattened primers and excessive case head expansion. Also be on the lookout for excessive recoil/report and sticky or stiff bolt lift (assuming you are shooting a bolt gun). When you get any of these signs, stop and back off your charge. Most likely the max charge for your gun/bullet/powder charge combination will be near the highest max listed in any manual. Go slow, and pay attention to any warning signs you encounter.

 

[GRingle]

Thank you. It is a bolt action. I will load as you suggested and watch for those signs of pressure. Thank you.

 

[RVTECH]

Only two reloading manuals? You should see my collection! The best advice? stick with your most 'modern' manual and start out with the loads on the lower end of the scale and work up carefully. Keep the old manuals around for reference reading and the coffee table and leave it at that. It is fun to look at the old manuals (especially the obsolete cartridges) but some of the data was for bullets and powders no longer available and using techniques and equipment from another time, some of which are not really relevant now.

 

[orygun]

I believe that you are right to primarily reference your Hornady manual when using Hornady bullets. There is a lot going on with bullet construction and shape that can influence powders. I know, and love, the Lyman manual, but it does not state exactly what bullet was used for the data. Hogdon's does, if I remember correctly, so it may list your bullet.
Just like every gun is different, I'm sure there is a difference in the test barrels used by different companies.
So, you've got a range that worked well for the test labs with your bullet and others like it. I agree with Greenbug for where to start. (approx 61gr) However I would load batches of at least 5 rounds per charge weight.
Now the fun starts!

 

[Greenbug]

Forgot to mention that the ambient temperature when you are testing your loads can influence your max pressure signs as well. If it is hot outside when you are developing your max load then you are probably going to be ok in any reasonable temperature. However if it is a cold day when developing your max load, you may run into excessive pressure signs when shooting the same load on a hot day. I believe that H4831 is one of Hodgdons "Extreme" lines of powder that are reportedly less temperature sensitive, but you should still take the temperature when testing your loads into consideration.

 

[deadshot2]

Having multiple manuals is kind of like having multiple scales. Which one do you believe when you get different "readings"?

If people were to add up all the money they spend on building their library of Reloading Manuals they'd see that they spent the same, if not more, for one of the excellent Internal Ballistic's programs on the market.

Whether it's Quick Load, Load from a Disk, or other, these programs are far better for determining a starting load (as well as "Danger Zone") than most manuals. Manuals don't take into consideration the internal case volume of YOUR brass. They also have an extensive database of bullets, even listed by stock numbers.

In the end, regardless of whether one uses a "Manual" or a "Program", it will all depend on your rifle. There are no two the same, period.

Of course if one wants to rely on their collection of "Flea Market", "Swap Meet", "Garage Sale" and "inherited" manuals, with the powders that are produced today, go for it.

 

[noylj]

You should ALWAYS start with the LOWEST starting load you can find. Even the lowest data was worked up with a REAL rifle just like yours, so your MAX load could well be under even the lowest max load you find.
You should know how to watch for signs of over-pressure. Using a bolt action, you have lots of good ways.

 

[Darkker]

The reason you see different numbers MOSTLY depends upon 2 factors:
1) WHO did the actual testing, WHEN.
2) HOW/WHEN/WHO made the powder.

"Testing" has been a mess of poop from the get-go. Only very recently did many begin to use universal recievers with a VERY close tollerance to SAAMI min spec chambers. Also it hasn't ALWAYS been corrected to a standard set of atmospherics. That lack of a standard parameter is how Lazzaroni's cartridges look so good. Velocities were tested at like 5,000 elevation

Powder lots ALWAYS have a variation. Remember that gunpowder isn't made by/for the private sector(reloader). It is all made by Gov't agencies, and Defense contractors for their purposes. Then it gets blended to a tighter "Canister-Grade" tollerance and re-purposed to the private sector.
When that occured, and with how many Non-Canister grades is what contributes to the lot variation. Call Hodgdon, or Western Powders(Neither of which actually MAKE any smokeless) they will give you the tollerance range, which is rather large with some powders.

Especially with Extruded powders, the Bulk Density(BD) and the Burn Rate(BR) must be kept in strict relationship to one another. ONLY the reloading community uses weight(not all of us ), The folks that make powder and ammo ALL use volume machines.


As long as the starting load ISN'T horribly(1/3) reduced over the other, nothing ill will come of it. Your specific lot may be slower and the necks won't seal well, leaving powder residue on the case; but that is about it.

 

[deadshot2]

The folks that make powder and ammo ALL use volume machines.

Yes they do. That's among the reasons you'll never see those who really want accurate ammo using "volume" dispensers like the manufacturers use.

There's also a difference between the Reloader type dispenser and one that sits in a factory machine measuring out powder for millions of rounds. One's optimized for the powder and machine, the other is kind of a one size fits all so it can be used with the "powder of the month" in a reloaders setup.

 

[Darkker]

1) That's among the reasons you'll never see those who really want accurate ammo using "volume" dispensers like the manufacturers use.

2) There's also a difference between the Reloader type dispenser and one that sits in a factory machine measuring out powder for millions of rounds. One's optimized for the powder and machine, the other is kind of a one size fits all so it can be used with the "powder of the month" in a reloaders setup.

1) MOST people, regardless of accuracy goals don't understand HOW extruded is made. That is why they don't use it. If more people understood the BD/BR relationship, they WOULD be using volume dispensing because of much better consistency. Another reason for so many using weight, is that accurate scales have been around forever. Volume dispensers that actually are calibrated in CC's have not. Most just have "graduations". A gent who occasionally posts on 65creedmore, is a Hornady factory sponsored shooter. He constantly wins matches with factory ammo. M118LR ammo is assembled with "reloader type" volume dispensers, that ammo is aimed at being accurate.

2)....Well maybe... I know that the Nosler plant uses off the shelf Dillons, so in that case, they actually ARE the same.

 

[deadshot2]

1) MOST people, regardless of accuracy goals don't understand HOW extruded is made. That is why they don't use it. If more people understood the BD/BR relationship, they WOULD be using volume dispensing because of much better consistency.

And yet I use extruded powders regularly and weigh every charge. The Bulk Density and Burn Rate issue is valid yet energy potential of a load is still based on the weight of the charge. A good volume dispenser like most are, from Lee to Harrels, will drop a charge that's close enough that for most purposes the argument is akin to "picking fly poop out of ground pepper". Weight is becoming so critical to some who shoot "almost over the horizon" are now starting to use the Sartorius electonic scale that is capable of accurately reading the weight of a single granule of Varget or other extruded powders.

Again, it's not a big deal when shooting at shorter ranges but when out there where you can't see your hits with a spotting scope weight wins out over volume every time.

 

[Darkker]

Short range is where it probably won't matter, but at greater distances, particularly IF you are trying to stay super-sonic to a distance is where the difference shows for volume.

Here is how it works, again, this is for extruded:
When using Weight.
If your powder has a higher BD, then it ALSO has a slower BR. So you put in the same weight, However now you have much less case fill, of a slower burning powder. So compared to the "standard" BD powder; Less volume of a slower burning powder gives you less pressure than what you were anticipating.

When using Volume:
Higher BD powder with a slower BR, you have the same case fill of a slower powder. Net effect is MORE(by BD) of a slower powder. That will give you very close to the "anticipated" pressures.

Scales give you weight, Volumetric devices give you volume, NOT a weight. VMD's give you a REFERENCE, but only a reference, to a weight.

Very good discussion on this topic over on shootersforum.
Poll on Volume or Weigh - Page 8 - Shooters Forum
Go to post #146, by Uncle Nick. He confirmed this with Western Powders.