1911 Recoil Master, spring combinations?

[Whistler]

I'm trying to figure out the ins and outs of the STI Recoil Master.

There are two strengths, light and heavy.
Light has green springs and is made for compensated guns and 9x19mm.
Heavy has orange springs and is made for .40 S&W and .45 ACP.

STI's product info:
http://stiguns.com/recoil-systems/

If you look at Brownell's they have a "twin pack" where you get both light and heavy.

If you look at the little peg on the left of both recoil rods, you can see that light has a long peg and heavy has a short peg.

Adding to the confusion is the fact that the RM is available for either bull barrel or bushing barrel. If you buy the bull barrel version you will also need to have the belly of the barrel milled flat so the recoil rod's head has room to move in.

If you look at the springs they are color coded as previously mentioned. The same color applies to both the large spring and the smaller sub spring. There is however no available info about what possibilities there are with putting a green outer spring to a rod with an orange sub spring or vice versa. Nor is there any info on the function of the long or short peg. What happens if you take a RM with a long peg and put in orange springs? The springs themselves are actually available in stand alone packages.

So to my actual problem:

I have a 1911 in .45 ACP with conversion uppers in 9x19mm and .40 S&W.

The upper in .40 has the flat milled belly and uses an orange RM since earlier. So far so good.

.45 is mostly used in Bullseye type competition, so I'd rather use a tungsten guide rod for the extra weight to stabilize. However, the barrel has been milled flat for a RM (which I ordered because it might be neat to have), but can I still use the FLGR with the horse shoe shaped rod head?

The 9x19mm upper is used for IPSC competition, so the RM would be nice for the fast follow up shots. It does not have the flat milled surface. The extra RM I bought used has the orange sub spring, short peg and a green outer spring. Can it be used on the 9x19? Are there any tables on the different combinations?

[echotango]

I think the small end/peg one is the old version.

[Whistler]

Negative, if you order the twin pack you get one of each, the long peg on light and short peg on heavy.

[echotango]

I stand corrected. Thx whistler.