First your choice of a Security Six is not the best choice in a revolver if you are going all out to be a winner.
WHY???
Reason #1: Speed Loaders
The Security Six cylinder spacing is not the same as the S&W K Frame or the S&W 686 L Frame / GP100.
In English that means you do not have a good selection of speed loaders. Pretty much the Turn Knob HKS MK3-A is it.
Now if you are just shooting for your personal enjoyment, the HKS speed loaders will work fine. They are just 1/2 to 1 full second slower to reload with than a Jet Loader or a Safariland Comp III.
Reason #2: Springs
While the Wolff spring kit
(Midway Number 734104) is reasonably priced at under $10. From the user comments it does not reduce the felt trigger pull much at all.
Reason #3: No Fiber Optic Front Sight available for a Security Six.
My advice would be to upgrade to a 6 Inch GP100.
You have a choice of L Frame / GP100 Jet Loaders or the Safariland Comp III Spring Driven speed loaders.
The Adjustable Sight GP100's have a Quick Change Front Sight system.
The GP100 has all Coil Springs

AND Wolffe makes a great Spring PAK for the GP100 with some choices in spring weight.
If you are stuck on the Security Six. By all means get several MK3-A Speed Loaders, and have a good time.
I make Kydex speed loader carriers, and I am pretty sure the K Frame speed loader carriers will work. I would need to measure a MK3-A to be sure about the diameter. I have almost every HKS speed loader in my
Try Box except the MK3-A and the J32 and K32. I guess I should add those as well.
The Kydex Belt Carrier shown is for a J Frame / SP101, but they are all pretty much the same design from a K22 to the 25-5 for a 45 Colt.
The Speed Loader in the Carrier is a Spring Driven J Frame Jet Loader, the one beside it is an HKS 36.
The HKS speed loaders will work just fine from the Kydex Belt Carrier. What will not work is a Safariland Comp I. Nothing to get a grip on with the tiny knob.
I hope I have been of some help. Nothing wrong with shooting to have a good time. You need a monthly match to shoot to stay sharp. I shot IDPA back in the 1970's. It got to be a job instead of a hobby, and I quit around 1977. I started shooting again the last 8 or 10 years. We were shooting Defensive Pistol monthly. The last 2 years we added lots of Reactive Steel, and we went to shooting Steel one month, and Defensive pistol the next. Last year we added ICORE Revolver on Sundays following the Saturday Match.
I can tell a HUGE Difference in my shooting since I started shooting a match every month. The whole gang that shoots with me have all made the same comment reguarding improving. Have A Great Time!
Bob
ICORE MO2908
Big Creek Kydex