Weihrauch works fine on my 586 fitted with a Magicniner adaptor- no clipping, quiet as anything and velocity fine- its that good, it has set up permanent residence
. I don't know what sort of adaptor was fitted to the 1911 so can't comment on that, (although I have seen standard CP88 adaptors fitted to 1911s and have doubts as to how well they fit which could induce such issues). Nick also does a "proper" threading for 1911s to accept a (supplied) adaptor- if its as good as the 586 one, its the way to go.
The Beretta adaptor is different from other standard ones for Umarexes, rather more secure IMHO, and should cope with most silencers. You could go for a lighter silencer, but if the adaptor is naff, you will still be likely to meet with problems.