Bluegill: Swirls in the crimp are often caused by a poorly set up final crimp. Generally, too much crimp. The crimped portion is too long. Most of your crimps show either some, or a lot. Not a serious problem...the shells will still go bang. But, the top of the shell at the crimp tends to bulge outward somewhat, which can cause loading problems.
As bertn accurately describes, inconsistent shell length(very common..usually minor. But does add to the problem). Plus, inconsistent technique during the loading process, can contribute. Most problems I've encountered though, revolved around press mis-adjustments.
Luckily, the cure is fairly simple. If you are loading on a MEC or similar press, it means adjusting both the pre-crimp and final crimp.
I could go through a long-winded explanation of how to do it. But fortunately, MEC offers a series of how-to youtube videos on how to set up their presses. Shouldn't be hard to find.
Of the two, I consider the pre-crimp to be the most important of the two adjustments. As this adjustment seems to have the most influence on the final crimp.
How much is enough pre-crimp?
In most cases, if a pencil eraser will just fit into the petal opening (about 1/4"), the pre-crimp is set up about right. This will take a bit of experimentation, as the lock nut holding the pre-crimp adjustment screw in place will need to be loosened/tightened several times. Usually a pretty straightforward process. Adjust only a little at a time.
Adjusting the final crimp is a bit more fiddly. The key here is to adjust the allen screw that controls the adjustment cam in very small increments only. Likewise, the crimp depth adjustment screw. The MEC video explains this process clearly. It may take a handful of tries to get it right....so take your time.
Will take a bit of trial and error. But, when crimps come out flat and tight....you're there.
If you're loading on a Lee Loadall press....the adjustments are pre-set and non adjustable. About the only option here, is to adjust the load column's height slightly. For example: Reduce the existing powder charge slightly. Switch to another powder. Reduce the shot charge. Go to a different wad, etc. In some cases, going to a different brand of hull makes a difference.
Here's a tip: When running the shells through the final crimp, do it in several stages. First: run the shell into the crimp die. At the end of the stroke, hold the handle down for a few seconds. This sets the crimp. Lift the handle a little and rotate the shell a quarter turn. Run it down again. Repeat,etc. You should feel less resistance on each stroke. Your finished shells should come out with their crimped ends perfectly formed and smoothly rounded, every time. An aid in smooth loading. Also makes a good, tight crimp.
Yes...this may add a few minutes to the length of time it takes to load a box of shells. But worth it, in the long run.
Learned this trick some years ago. As an active cowboy action competitor, I know that championships are often won or lost on shotgun stages. So...shotshell loading and shucking through my double barrelled guns must be fast, smooth and consistent....every time. Where fractions of a second can make the difference between a Champion buckle and "thanks for showing up"....little tweaks like this can often make a huge difference in performance.
Of course, your needs may not be as stringent. But, there is a great deal of satisfaction in knowing that your final product is as good as.....or even better, than factory.
Hope some of this is useful.
Al
ps: Don't be surprised if you need to make minor crimp adjustments when switching from one brand of hull, to another. Very common. By the way, a pretty good batch of shells, for your first try. Have loaded many that looked like that, too. Shoot them with confidence. Your shells will improve with experience.
