IME over a period of many years, a
really heavy gun won't be well enough supported by elastic suspenders. They'll help, but things will still sag to one side. If you choose such, the Perry brand, which attaches to the belt, and the Holdup brand (
Holdup Suspender Company manufacturers of the patented no-slip suspender clip), which attaches to the pants waistband, are your best options IMNSHO, and I've used them for years with lighter weight guns plus all the other gear that goes on my belt.
The Perry varieties are all elastic, even the "heavy duty" ones
except for one; that's the Industrial Original Perry Suspenders, which use non-elastic polymer webbing for the two main straps, with only the support-brace strap at the rear being elastic.
These work best for me for carrying all-steel 1911s or revolvers.
I will even use the lightweight nylon Occidental Tool harness suspenders for helping to support a heavy sidearm plus two reloads plus multi-tool plus keys plus other stuff sometimes!
A gun on the belt supported by suspenders is basically a form of low-riding shoulder holster, and every type of support can be helpful when it coms to carrying around a three pound chunk of steel on one side of your body.