SA ILS mainspring housing

I've had good luck with a simple Wolff mainspring change in the SA ILS housings. My RO, with the Wolff 24# reduced power mainspring (& a touch of Neco-MolySlide every few hundred rounds on the hammer hooks) is right at 3½ lbs and feels great. --I've had 100% ignition reliability with it. - I know-the number 24 doesn't sound right-trust Wolff. - 
Question:
Unless changing sear/hammer, etc. also, what are the reason(s) for swapping the SA ILS (locking) mainspring housing to a standard housing? - Unless you want flat instead of arched or vice-versa. With the reduced power Wolff ILS mainsprings available, I don't see  reason for it. - -  ??
Thanks, Russ OR

Are you sure the stock SA spring wasn't 23 lbs.?  That is the number I got from Jim Williams in the SA Custom shop.   I also tried the Wolff 19 lb. replacement spring in my RO but it was too long for the MLS and would barely tuck in the MLS.  Wolff refunded my cost.  Just wondering.

The SA ILS reduced power mainsprings from Wolff are 24-26-28. Stock is 30!!.-The #s don't/won't jive with standard mainspring #s. --- Not positive without looking, but I think the Wolffs are longer. TRUST WOLFF - Several of us did and are happy.  [url=https://www.gunsprings.com/Semi-Auto Pistols/SPRINGFIELD/1911A1 SERIES/cID1/mID60/dID267]https://www.gunsprings.com/Semi-Auto%20Pistols/SPRINGFIELD/1911A1%20SERIES/cID1/mID60/dID267[/url] .The 24s have worked fine on the 22 conversions too. ---- the little take down pin that comes with the ILS housing makes changing springs easy-just don't push it (the little pin) in too far when re-installing the housing on the pistol.
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Bigtrout, you need to search here for Robs procedure for updating the ils to use standard 1911 parts.

I don't compete with my RO so I don't have to have the ILS to be legal. I changed the housing purely because I am offended by all the infernal internal locks becoming prevalent these days. I do own a couple of Ruger revolvers that have them but Ruger was nice enough to NOT drill the hole through the grip panel (optional for the consumer to do at that time) so I can't see it. There are a couple of S&W revolvers out there that I would own were it not for the safety lock 'feature' but that is just me, I believe that safety originates between the ears of the operator and that the locks are a distraction.

Bruce

You don't need the ILS to be legal.

james r chapman wrote:Bigtrout, you need to search here for Robs procedure for updating the ils to use standard 1911 parts.

Thanks, James.  I've gotten my pull down to 44-48 oz. by bending the disco and sear spring legs per Jack Wiegand's tutorial.  The question posed to Russ by me was prompted by his installing a Wolff replacement spring in the ILS housing.   Jim at the SA custom shop did tell me that the stock SA RO is 23 lbs., not the 30 lbs. specified in the owner's manual.   Woflf's replacement ILS springs are 5/16 inch longer than the unloaded length of the SA ILS mainspring. When I spoke to Wollf's tech he said he did not know the ILS mains were so short.  The Wolff spring had the same number of coils and same wire diameter as the stock spring.  I am aware of changing the ILS MSH to the standard but chose to stay with the stock MSH after I did the leaf spring modification.  I do have a little creep in my trigger but it's hardly noticeable and I'm getting my new shoe from Frank today at the PO and looking forward to see how it feels.  I gotta tell ya, you folks are most helpful to me and it is much appreciated.

You just need to change out the internals, you can retain the original ils msh.