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Joined: 23 Jan 2008 Posts: 224

What makes a shell consistent in pressure and velocity? Is there any rule of thumb for components that makes it more predictable on what your outcome will be when trying a new reload combination?

Also, when does inconsistency in a reload become too large for a load to be useful? Is 500 lbs EV too much? 1000 lbs? 1500 lbs? 25 fps EV? 50 fps? 100 fps?

Joined: 06 Aug 2009 Posts: 960

Tom Armbrust taught me to use 1,500 PSI and 35 FPS as maximum extreme variations for consistency on any load. It worked out very well. Those figures are based on 10 shot data strings. For 5 shot data strings you probably need to tighten that up a bit. 3 shot strings IMO are a waste of time and money.

For consistent loads, the rules of thumb from my experience are like this.

Use the faster burning powders for the shot payload and internal size of the shotshell. If you go too fast on burn rate, the pressure will spike real easy with small changes in powder weight, too slow with the burn rate and the load will not develop enough heat too burn consistently. Both will cause inconsistent numbers

For most lighter loads with fast to medium burn rate powders, use a primer like the Winchester 209 to start with. If the load is not consistent enough try either hotter or colder primer. For slow burn rate powders like Blue Dot, Steel and Longshot either a CCI209M or a Federal 209A. Sometimes the Winchester 209 is OK with Blue Dot and Longshot but the hot primers should be the starting point.

Pressure is your friend. Keep the fast burning powders above 8,000 PSI and the slow powders above 9,500 PSI. Pressure helps in cold weather a lot, If your load is 10,000 PSI and higher, cold weather drop off will not be a consideration. That is across the board with all powders, assuming you are not using a mild primer with the slowest powders. What happens at 68 degrees F with a mild primer will not happen at 0 degrees F.

Crimp depth and uniformity of the crimp. 3/64" to 1/16" deep crimps that are well formed, with a slight taper. 8 point, 6 point and roll crimps must all be formed correctly, none have any real ballistic advantage over the others.

Hulls must be in great condition for consistent ballistics. The slower powders NEED once or twice fired hulls for proper combustion. Personally, I won't use anything but new or once fired hulls for hunting loads, I don't care what components are inside.

Wads, don't use a wad that you know has the chance for powder migration.

If I have to add a filler I toss the load aside. BUT If you absolutely need to add fillers, hard card wads are best, felt and fiber wads are next.

K.I.S.S. - Hull, primer, powder, wad, shot, crimp.

Don't add stuff to a load, mylar wraps, buffer, little squares of plastic, cheerios, lima beans, toilet paper(yes I know a guy that used it for filler) ETC. If the components of a load are lacking or the load doesn't fit in the hull properly get rid of the load and find one with more suitable components. I know there are exceptions.

Lastly make sure your reloader drops +/- .2 on powder and +/-10 grains on shot. For crazy perfectionists, go ahead and hand weigh if you must. It won't hurt, but it won't change much. The 2 powders I will hand weigh are 800-X and Steel they are just too fluffy to drop consistently.

That should do it.

Joined: 23 Jan 2008 Posts: 224

Interesting,

For the few primers I use, I have actually found the cheddite primer (what comes in the new cheddite hulls) to give me the more consistent loads when using longshot powder, especially with some of the heavier loads I have created. Of course, the consistency might be because I am using a new hull in those loads.

For Steel, I agree the "hotter" primers are the way to go...and I have had good luck with the FED209A.

I do hand measure all my loads that I have tested, and try to stay away from wad/hull combinations that can cause powder migration. Even this is strange to me though, as I have one load with an SP-16 wad and a cheddite hull that is reasonably consistent, despite how loose the wad is in the hull.

Thanks

Joined: 06 Aug 2009 Posts: 960

Yup the Cheddite primer is fairly robust, I am sure that with Longshot it works well.

If the powder doesn't migrate, there is nothing wrong with the wad being a little loose. It won't have any affect on things.

You have to hand weigh any load that you are having tested.

In my experience, the crimp is the #1 cause of inconsistency. Once fired hulls will be the most consistent (everything else being the same) in extreme spread of speed and pressure...which of course affects your shot pattern. The more times you reload a hull, the less consistent they become. You have to decide when those reloads become unsuitable for their intended use, be it claybirds or real birds.

Your criteria and advise are pretty sound IMO. Experience has taught me pretty much the same things.

However, in some cases, adding, subtracting, or modifying componants becomes necessary due to a lack of alternatives. This has been true for reloading for the 16, but is improving. However, if componants or methods must be modified to achieve a certain result, it should be done with caution and a reasoned, consistant, and safe approach. First, consult with an authority like a professional ballistics lab technician or componants manufacturer rep before proceeding. Listen to his advice. Reduce the powder charge to a safe level as well. Then proceed with caution and check the loads for safety and performance as you go to avoid any nasty surprises or poor results. If you can't do these things, then stick to safe published data and accept the limitations.

Joined: 06 Aug 2009 Posts: 960

Glad I have your seal of approval, I was having trouble sleeping without it.

You sure it isn't gas? Smile