I fly the small size on 4inch M rockets . They are rated to 70 lbs. I let the diameter dictate the button size more so than weight.
On tall large diam. I go to the 1515. Usually 30-35lbs and 6in. diam. is where I switch.
I have flown my 6in Ultimate Endeavor on small buttons where there were no larger rails several times without any drama.
Actually there are 2 sizes of 1010 buttons. Normal and small or streamlined.
The normal ones will ALSO work in 1515 rails. I fly mine in them all the time.
Next time your at a launch take a button out to the 1515 and check it out.
Especially if like most clubs that don't clean their rails. You will get a better, less binding fit by using the 1010 buttons in the 1515 rail.
This will NOT work on BlackSky rails.
Thanks all for the info.
Looks like I will go with the small buttons with provisions in place to be able to install large buttons later if necessary.
Jim I test fix some small buttons on a 1515 rail I had on hand.
Looks like you are correct on that. Thanks for the info
On the subject of dirty rails I think we will see more of that.
One reason will be more and more fliers flying SkidMark motors.
They dirty up a rail in short order.
I have a 1010 rail that I have flown quite a few flights off of.
It looked good as new until I flew a SkidMark off it.
Very hard to clean.