I have some times been able to get good castings, at others not.   I'd like to get really good high definition ones from the Aydt because the chamber looks "non-standard" for an 8.15x46r. However  the three castings I have done so far all come out wrinkled in spots with trapped air pockets on the surface.   

I plugged the bore about an inch or so into the rifling by carefully tapping in a soft-alloy well-greased bullet, much like a really deep breech-seated bullet. 
  I'm wondering if that sealed too well and trapped air.  In the past I have used a wadded up oiled patch--maybe that let air bleed out as the alloy was poured in. 
Would heating the barrel with a hair dryer or electric heat gun before pouring the alloy in help?

Found heating action and barrel to about 75-90° if possible with heat gun/hair dyer plus oiling gives the best casting, rough chambers and barrels are the most difficult and require waxing with Imperial sizing die wax, it does not give the most accurate of castings but you can usually get them out.

Mike

Warm a stripped action, but remember that to much heat = expansion, enough to matter, I do not know, but I do know that the action just need to be 'warm'.  Also, cerrosafe melts at a very low temperature so it does not take much to melt it.  I use a heat gun to warm parts and cerrosafe.  Work quickly for best results.  It does sometimes take a couple of tries to get a good cast.
Cary

i'll give that a try tomorrow afternoon.

thanks Texas-Wayne  that was very good.   great for future reference.   
Unfortunately, for some reason on my Mac (an older MacPro laptop running 10.6.8 running Safari 5.1.10) the time/dimension shift chart was overlaid over some of the text.  fortunately I get the gist of the article--cast it right and don't wait too long to measure.

Agin thanks to ALL of you who responded.

Michigan-Wayne Stiles