Reverse Engineering Lapua Factory Ammo Part II

[Afy]

Well, having figured out that the Lapua ammo has 30.3 grains of powder for their 105 Scenar Load for 6mm BR, I loaded up some ammo to test using 30.3 grains of N150, N140 and 30.2 grains of N540 since Quick Load was showing 30.3 as being dangerous.

So the weather being rainy, and a switching wind of about 10 mph was making things difficult. Anyhow set up the target at 100 meters and off I went.

Any how the N 540 grouped reasonably well at about .8 inches edge to edge.
I blew the first N140 group, but the second one grouped to .748 inches or there abouts. Or about .501center to center.

Pic below:


Then I cleaned the barrel, couple of patches with KG-1 soak for 5 minutes, three dry patches and on to N150..

First group was a shade under .665 or .422 center to center. Which was promising.



Last five shots of the day were the N150 cartridges again.

And a group of .350 edge to edge or .107 center to center..


Who would've thought the humble Savage could do this. The Barrel is a 26 inch LW with a 1:8 twist. Or for that matter that Lapua most likely uses N150 in their factory ammo. More testing with N150 to follow.

 

[cougar1717]

I'm not sure that you will be able to reverse engineer a factory load. Ammo manufacturers buy powder by the railroad car, formulate loads based on the powder lot, and then manufacture. The next powder shipment they buy may be slightly different, so the formula usually changes for each lot.

 

[esheato]

Who cares about whether it's possible or not....load up a bunch of N150 and call it a day.

Well done Afy.

Ed

 

[Marlin 45 carbine]

I don't shoot that round but nonetheless an interesting post, I appreciate the diligence involved in working up those good shooting rounds.

 

[Jeff H]

I'm not sure that you will be able to reverse engineer a factory load. Ammo manufacturers buy powder by the railroad car, formulate loads based on the powder lot, and then manufacture. The next powder shipment they buy may be slightly different, so the formula usually changes for each lot.

got a reference for this statement?

IMHO, I doubt that anyone reformulates a charge based on the latest powder shipment, it HAS to be better controlled than that.

 

[BullfrogKen]

He's right. That's pretty much exactly what the big name ammo manufacturers do. Sometime the powder used isn't even available on the open market. Other times it's a blend.

Either way, exactly duplicating a big factory's load with what we have commercially available to us on the consumer market is just not always possible.


But who cares? Develop a load made for your rifle, and be happy. Handloads will always have the potential for better performance than factory loads for no other reason than you're able to tailor your load right to your rifle.

 

[Afy]

Ah well.. I just want to reproduce the .107 c2c group.

Part 1 if you want

 

[243winxb]

I'm not sure that you will be able to reverse engineer a factory load. Ammo manufacturers buy powder by the railroad car, formulate loads based on the powder lot, and then manufacture. The next powder shipment they buy may be slightly different, so the formula usually changes for each lot.TE] Why not when the bullet & powder maker are the same. http://www.thehighroad.org/showthread.php?t=481607

Lapua FAQ -
Quote:
Which powder is used in cartridge?

Our strategy is not to inform individual factory loaded cartridge powder types or powder volumes. Matching powders and volumes are presented in our reloading guide, in principle thus also including our factory loads.

Looks like its possible to me.

 

[FROGO207]

Afy
Looks like you are on to something good here. Have fun with it.

 

[BullfrogKen]

Looks like its possible to me.

What you quoted from Lapua's FAQs is telling you flat out they aren't going to give you the "recipe" the factory uses. They are telling you that if you buy XXXXX commercially available powder and load it with XXXXX volume, you will be able to duplicate the load in performance.

Duplication is not the same as replication. And its certainly not reverse engineering.


Ammo manufacturers use powders that aren't even commercially available. Sometimes even the manufacturer can't duplicate the same load from the previous batch. Its not uncommon for a manufacturer to use a mixture blended up just for the run in current production based on what's in stock.


I don't understand the desire to reproduce a factory load. I've never had a factory load shoot as well and my handloads. Ever. Develop a load that works well for your rifle and enjoy.

 

[Afy]

Actually Lapua's 6mm Norma BR cartridge is known for its accuracy and consistency. Most of the ISSF crowd use it quite extensibly.

 

[rodregier]

BullfrogKen is giving you the straight scoop.

Major categories of smokeless powder are cannister-grade and non-canister-grade. The cannister-grade offerings are targetted at hobby reloaders, and are held to certain permissible variance standards by the manufacturers. This enables them to sell a product with associated loading data that will fall within a fairly narrow tolerance band. The non-cannister-grade powders are not held to the same tolerances as packaged, so there is more lot-to-lot variance allowed. (Smokeless powder production is a bit of a black art, the result of each production run is somewhat variable. Winchester Ball powders were one innovation to permit last-step adjustments by controlled flattening of the tiny balls of powder.) The non-cannister-grade powders are sold in larger container such as 60, 100 pound drums or larger but at lower unit pricing. Multiple containers from the same production lot would be sold to the end user company. The measured amount used in an ammunition production lot for a cartridge formulation is adjusted by the factory ballistician to produce the correct pressure/velocity with each different powder production lot.

One of the smokeless powder packagers/resellers in Canada (Higginson's) has sold non-canister-grade powders in the past, I've used some of it and some from another source too. It's rather fun to do metallic cartridge load development beyond what is laid down in a reloading manual. The available info for the sold powder will characterize the powder as "similar to" xxxx. So, you use the published data for xxxx as a starting point, start low and carefully work up, observing the usual pressure signs. Ever seen IMR 4896? (not 4895). I have I like to think of it as IMR4895SC. Pretty handy for .223 Rem.

 

[BullfrogKen]

Afy,

That might be so. But world records are not broken with factory ammo. Serious competitors don't compete with factory ammo.


It might be really good, but it's still made to looser, "one size fits all" tolerances. I can tailor my neck-sized only, handloaded ammunition to outperform anything factory in the accuracy department.


Quit worrying about what the factory produces. Develop a load your rifle likes and be happy. One of the benefits of handloading is the ability to outperform the factory.

 

[Afy]

Oh I am having a lot of fun. And the rifle is shooting well too..

 

[BullfrogKen]

Here's a snippet from an interesting article discussing how factories produce ammunition.

Enjoy.

What's in a number? IMR vs. Hodgdon

The business of making and selling gunpowder is confusing to most reloaders. Only two companies, Alliant and St. Marks Powder actually manufacture smokeless propellant in the United States. Since DuPont got out of the powder business decades ago, IMR powders have been made in Canada by Expro Tech and simply distributed by IMR Powder Co. Hodgdon's powders with the same numbers are made in Australia by Australian Defense Industries (ADI).

......


Extruded powders are usually manufactured in batches of around 5,000 to 15,000 pounds at a time. When done they are tested against a reference lot. If a particular batch does not fall within the specifications for a specific powder name or number the manufacturers are able to blend with lots that may be a little slower or faster to get a lot of powder that falls within specifications. When the powder gets to Hodgdon they check it again against the same reference lot. Both reference and new powders are shot with the same components and at the same conditions of temperature and humidity. A number of 10-shot strings are fired in SAAMI standard test equipment and both pressure and velocity are measured. If the new powder is within /- 3 percent of the reference lot it is accepted and packaged.

3-Percent Rule

My guess is some of you are thinking a 3 percent tolerance is pretty big. Not so. In fact it is a very tight standard when you remember the variability of our system. It really isn't too rare to see a 10-percent variation in either pressure or velocity with a not-so-hot load. In the laboratory, variables can be controlled far better than we could ever hope to, whereas we are at the mercy of the weather and all of the different variables of our own production guns.

Of course many reloaders look at the data in somebody's manual and assume that they will get exactly the same thing down to the nearest tenth of a foot per second when the fact is we are lucky to come within plus or minus 25. Velocities in manuals are just a guide and the only way we can ever know what our loads are doing is to chronograph them ourselves. If you really want to get frustrated, shoot the same load, in the same gun, during each of the four seasons or in climatological extremes of temperature and humidity.