Helper springs on longs? I use 'em, not to add to holding power, the mechanics of longs do that by themselves. I added them just to make them a bit faster. I too am a fan of #2 longs, one of my favorite predator traps. I also use #11s for coons. Here are a few pics. Sorry for pic of mangy coyote at bottom, does show my booster springs on the #2s. I took a REALLY cheap mod on mine and just used a few wraps of wire at the bend to help hold the booster in place, that's all. Just want to keep it in place, dye and treat it with rest of trap and it lasts for years, seriously. I haven't replaced any yet and that's about 30 years of use, seriously! Fun thread, thanks for all the cool posts and pics, everyone. Oh and yes, you can take a singe long and make it a double long, but the shape of the jaws is key. Older style jaws that were symmetrical, work great. some though are not symmetrical, a little more squared off on one side and not on the other side, those do not work.
Jim
Here are couple of singles modified into doubles. First is a 1.5 single with symmetrical jaws, and a second spring added...to make this a #2 long. I also center swivel all my traps, and don't forget to do some filing on the pan & dog assembly, as well as squeeze the eye of the dog a bit to take the travel/play out of it.
Here is the #2 I made out of an old 1.5 long with symmetrical jaws...

Here is a #11 made out of a #1, again the #1 had symmetrical jaws...

shortening the travel of the pan and making the dog fit the pan notch better with a little filing work...

Couple of badgers in modified #2 longs...
first one you can barely see it but that's wire wraps at the bend of the springs, holding the boosters in place....

Some cat pics, all in #2 longs


Coyotes in #2 longs...



coons...well they are prevalent here and any predator set I make will take a coon also, and since coon are bread and butter of our fur market here I won't be upset to find them in predator sets...but means I have to lean toward smaller traps that will work for anything I can catch here too. can see wire wraps at bends of springs here too, holding the boosters...
and of course, #2s on fox...a great fox trap...
Again, sorry for the ugly coyote pic, but shows the hold of #2 long well adjusted, and the booster springs in place, held in place at bends by several wraps of wire...
Jim