Start with 3.4g of Bullseye and work your way up. 3.4 will be a powder puff BULLSEYE 10Xring accurate load all the way up to 3.8g.
What rate recoil spring do you have in your 1911? With the above light load, you may have do drop down to a 13# recoil spring or even less.
You will know to do this if your spent shell gets caught in the ejection process or you start having the slide not stay open after the last round.
Watch where the cases drop... on these light loads, they sometime only gently flip up and over about 1 foot.
Do not load up loads of rounds at the low rates.
I would do 15 (3 5 shot groups) at 3.4, 3.5, 3.6, 3.7 and 3.8 and see from rest what works any cycles best.
Bring a few low weight recoil springs and bushing wrench with you to the range.
Use different targets for each load so you can analyze the results.