I mainly use Loctite/Araldite while its expensive, alternatives like Marine-Tex are not widely available in EU , shrinkage is where its at , unless you plan to redo the bedding every season, which is quite often done by some folks in the BR world particularly in wood stocks that move quite a bit.
epoxy resin shrinkage is typicaly 2-7% but depends on fillers, in any case, shrinkage is volumetric so the thicker the bedding more it shrinks. I would actually be surprised if the 0.1% Speedy mentioned for Marine tex is quite accurate as much of the shrinkage occurred before he machined the blocks to size. So was more a test of long-term stability than overall shrinkage.
''Speedy about bedding compounds. Speedy offered some interesting advice based on long-term testing of various materials. Speedy favors Marine-Tex because it is very stable over time, while other materials can shrink up to 6% dimensionally. A good bedding job should be a perfect fit to your barreled action. If the bedding material shrinks over time, that is NOT a good thing….
Speedy’s customer asked: “I know you’re not a Devcon man in regards to bedding compounds but I respect your input in such matters and my question is this in regard to aluminum actions. If Devcon was considered, for an aluminum action, would you prefer aluminum compound formula or steel formula? I personally prefer Devcon steel and Marine-Tex for steel receivers but my experience with aluminum is limited. Also do you have a release agent preference that works better with aluminum?”
Speedy answered: “My only preference of one epoxy over another is their stability over time. My buddy who works for the Texas State Weights and Measures Department had me cast several of the most common types of epoxies used for bedding into 1.000″ machined blocks. After one year of being kept in a controlled climate and measured for shrinkage monthly, the Marine Tex shrunk only 1/10th of 1% (i.e. 0.1%) whereas almost all the others (including Devcon Steel formula, Devcon Aluminum formula…) shrunk 3% to 6%. The only other compounds that matched the Marine Tex were Araldite 1253 and Araldite 2014, with the latter being quite expensive for daily use.”