SMK vs Hornady...weird results

[steel1212]

I've been working up loads for my Clark Gator and have tried a technique I got from Glen Zediker in his book 'Handloading for Competition'.

Say you've picked all your components and now just need to figure out what charge will work best in your rifle. Start with your minimum charge. 25.0gr for example. Load one cartridge. Load the next one at 25.2. The next at 25.4. Continue till your max load.

Load the hottest load first in the mag continuing in order till the softest. Set a target to 200yd. Bag or rest the gun so your point of aim is repeatable. Shoot each round making notes as to the exactly where the bullet hit. You'll need a spotting scope or what I do is set up a camcorder a few feet uprange from the target to film the hits.

What you're looking for are the sweet spots. Ignore the deviations from windage. Places where 3 or 4 bullets are impacting very near each other in elevation. When it falls off the sweet spot the bullets will start going high and low till it finds another sweet spot. Hard to describe but the illustrations in the book make it clear.

Didn't believe it would work but I loaded up a few at one of the sweet spots. First try at it with Hornady 52 A-Max and AA2015 resulted in sub MOA. Easy A zone hits at 300yd unsupported prone. I've got more work to do but for a first shot at it the results were impressive.

Hank, that actually sounds like a pretty darn good idea. You'll see what tenths of grain group well together then you can work it to the final tenth....I'll have to try that. To bad my big 3 gun match is tomorrow lol.

[Patrick Sweeney]

In all cases, you load what the gun likes. I had a 20" 1/12 pencil barrel that shot Winchester 63 grain softpoints into one hole at 100 yards. It wasn't supposed to, but it did.

So I bought a truckload of those and shot them until the bore was gone.

[Dan Sierpina]

Hank,

That test was from Creighton Audet. A gunsmith and highpower shooter from Vermont. He came up with that system a long time ago to minimize the time testing ammo, hence saving the useful life of a barrel.

[Hank Ellis]

Hank,

That test was from Creighton Audet. A gunsmith and highpower shooter from Vermont. He came up with that system a long time ago to minimize the time testing ammo, hence saving the useful life of a barrel.

Thats the one. Couldn't remember the name of it when I did the above post.

Although I got decent results the first time out I loaded a bit short as per the Hornady manual. 2.230" Per the Sierra manual I can go to 2.250". Got another batch waiting for range time. Also have Hornady 55s I want to try out for 3-gun and leave the A-Max for really serious accuracy work.

Like Steel1212 I've got a 3-gun match in about 10 days and my load isn't ready. Guess the MagTech will have to do. But the targets are only to 75yd so it shouldn't be an issue.

For more information on the Audette method try http://www.washtenawsportsmansclub.org/gro.../incredload.pdf

[Dan Sierpina]

Since I don't crimp rifle ammo, I load just short enough to fit in my mags. 2.250 is a safe length for all my mags.

[kgunz11]

Audet and Zediker were doing a ladder test. There is actually a variation of that that has spun off that is much more effective since it's results compensate for temp sensitive powders and variance between cases powders and primers.

It's called the OCW theory (Optimal Charge Weight). I've used it a ton for long range precision rifle stuff (1000 yards and beyond) and it's awesome.

Dan Newberry is the author of the theory and he has some real good info on his website. He's a down to earth redneck type like a lot of us and his writing is real simple to read and understand.

What is an Optimal Charge Weight load?

With any given bullet and powder combination, there will be a specific amount of that powder which will cause the bullet to exit the muzzle at the "friendliest" portion of the vibration cycle. This does not necessarily correspond with the tightest velocity figures, however. Many load recipes have over the years become the "go to" recipes for trying out a new rifle. If your rifle fails to shoot one of these "tried and true" recipes well, you may well have a rifle integrity problem. Consider the Federal Gold Medal Match .308 win ammo. How can one recipe shoot so well in so many rifles? That's what we're after in the OCW load--a load recipe so stable and predictable that it does indeed rise above, and to some extent disprove the "all rifles are different" adage of lore...

Recent conversations with very learned mechanical engineers are affording me some better understanding of just why an OCW load works so well in the majority of rifles chambered for the cartridge at hand.

Here are some of the major points coming to light:

Uniformity of velocity (meaning low extreme spreads of velocity) are definitely not an indicator of the OCW zone. We are actually finding that in many cases the OCW zone does not have the tightest numbers--at least initially. Fine tuning of the recipe with seating depth variations and primer changes will improve the velocity consistency, but simply shooting a succession of graduated charges over the chronograph and looking for a tight velocity spread will not lead you to the OCW. As the reader comes to understand more about the main shock wave (link Chris Long's pages at the bottom of this page) it will become easier to understand how bullets with larger extreme spreads in velocity can still group tight (at closer ranges), while bullets with seemingly tiny extreme spreads may group poorly. You can tighten the extreme spread to improve long range accuracy AFTER you identify the OCW.

Engineer Chris Long's model of barrel behavior suggests (simply put, and in part):

The initial shock wave, generated by the powder charge's ignition, travels at a given rate of speed from the chamber to the muzzle, then back, in a repeated pattern. When this wave is present at the muzzle, there is naturally much turbulence and obturation of the "roundness" of the bore at the muzzle. However, when this main shock wave has reverberated back to the chamber end, the muzzle is relatively stable. This window of opportunity, according to Chris, is the best time for the bullet to exit the muzzle. The barrel is basically straight, and relatively calm.

The OCW load would then have the optimal amount of powder to push the bullet at just the right speed to be exiting the muzzle when this shock wave is at the other end (the chamber end) of the barrel.

This shock wave travels at the same speed regardless of barrel length or girth.

We note that OCW loads seem to perform very well regardless of barrel length. (We're not considering non-typical barrel lengths here). This makes sense because the relationship between barrel time (the length of time it takes the bullet to exit the muzzle) and the oscillating shock wave is nearly the same; in other words, in a short barrel the shock wave reaches the muzzle and returns to the chamber faster, but alas, the bullet reaches and exits the muzzle faster also.

The harmonics which ride the main vibration node are only of minor importance to accuracy in most cases. It would appear that the effects of the subtle harmonic vibrations can be largely negated with seating depth adjustments, but a true OCW load will normally be MOA or better in a good rifle without seating depth tuning.

If you perform the OCW load development properly, you are not (in the initial stages) seeking the optimal load for the test rifle. Heresy? Not really. There are many known "universal recipes" that work well in most rifles chambered for them. Ken Waters has made a pretty penny with his book "Pet Loads" on this concept. Many of the Waters loads have worked beautifully in my rifles, and acquaintances have had the same experience.

Federal's Gold Medal Match .308 loads do well in practically any .308 not needing a gunsmith's attention. How can this be? If you subscribe to the philosophy that "all rifles are different," and therefore need individual loads tailored to accommodate their idiosyncrasies, how do you explain the near universal MOA performance of loads such as the Federal GMM?

Universally good recipes do exist. Upon realizing this, my questions have been "How do such recipes work?" and "How can I identify such a recipe?"

Here's the link to Dan's OCW Theory website, check it out for more details and photos.