The reason nobody can make an f1 auto is that they didn't use the Burmese Pure which is a very special land race sativa. It grows in Burma high up in the mountains just underneath the cloud layers and into the clouds. This is a low light area and the light is very blue because the reds are filtered out by the clouds. It is very cool and damp and therefore the plants are mold resistant. The growing season is very short with early frosts. After many hundreds of years it has adapted to these growing conditions. These conditions are similar to ruderalis which has low light due to the angle of the sun, cool conditions with a very short growth cycle with early frosts. Similar to ruderalis Burmese Pure has a very short growth cycle and is short in stature at 5.5 feet. According to Reeferman it frequently shows PRE-FLOWERS even under 18 or 20 hours light cycle. This is what I have found as well and when I switch to 12/12 it just bursts into flowers. Because it grows in very similar conditions to ruderalis it has turned into a race that is ALMOST an auto. So, it is very possible that crossing the almost auto with auto Hindu Kush that the first crossing would show auto. Also Auto Hindu Kush is one of the originals and has a heavy ruderalis quotient. It also might be mountainous as is the area of Hindu Kush.
I didn't think about Burmese Pure being an almost auto. I just made the cross because I love the Burmese Pure and was planning to make many generations and filter them out for auto. It's very easy if you just grow on 24 hour light cycle and throw out the non-autos and keep the auto males.
However when this happened, and I got the autos on the first crossing, I thought it was very interesting and that it would be interesting for the forum viewers to see.
I always grow from seed and have hundreds of seeds of this cross from 3 different mothers and two different fathers. It's easy to pop a few seeds and put them under 24 hours with my other autos and try to stabilize them for auto.
My next project might be interesting as well. Upstairs in the vegging closet I have 2 Muay Thai auto fem a little more than a week old in 5 gallon pots. They look great and waiting in the crisper are 8 seeds of Auto Lemon Haze non-female. Hopefully I can get a male and make some nice seeds of Hazy Lemon Thai. I'll let the Muay Thai get ahead a bit and then start up the non-fems.