i take 4 ea 4'x 1" x 1/4" steel straps! match drill em all to a #7 drill bit! 2 holes per strap, seperate em! tap half of the for 1/4 20 bolts, clearance drill for the rest of the straps!
then i match drill the barrels together with the straps (straps just seem to add additional strength less pull thru of bolts) use bolts no nuts/ screwed into the tapped portion of the strap, any excess sticking thru grind it off..
might be extra work but has eliminated a lot of pull thru bolts and washers including fender washers