When I've been doing chamber casts, I've been getting about 3-4" of the rifleing at the same time. It gives a nice impression of the inside of the barrel. You'll just have to measure soon so it doesn't expand and give bad readins later.
Anyone see any problems with doing it this way? It won't give you the feel for the whole bore but...

lar: That's a good way to do it; it also gives you valuable info on thoat dimensions and wear in the first stretch of rifling. I've also made casts of 3 - 4" at the muzzle, for comparison, and to spot cleaning rod, etc., damage. If I remember right, for the CerroSafe material sold by Brownell, the final expansion is only about one-quarter percent, or around 0.001" at 40 caliber, and this is easy to figure into your measurements. With its somewhat higher melting point, Dan's mix must be a different alloy, and may have a different final expansion figure (I don't have data on it), but it can be used the same way. Very useful stuff - but it's a good idea not to over heat it (cadmium, etc.) and best to keep a separate Ideal or Lee stove-top pot and dipper exclusively for chamber/bore casting. floodgate

Care to explain the barrel cast method... inquiring minds wanna know..

marlinlover: Exactly the same as doing a chamber cast, but easier, as you don't have to work around extractor, bolt lug, etc., recesses. Oil the (cleaned) bore lightly and wipe with one patch to leave a slight film. Run a dowel up from the breech to within 3-4" of the muzzle, pushing a cork or a wadded-up cleaning patch, preheat the barrel with a hair dryer until it is uncomfortable to the touch, heat the chamber cast alloy until it just melts (185F or so for CerroSafe, somewhere around 225F - I think - for Mtn. Moulds' mix) and pour it in full up to the muzzle. Blow cool air onto the barrel until it sets up solid, plus a few more minutes - but not over 15 minutes, as the alloy starts to expand again in a half-hour or so, then rap the cast out from the breech by tapping the end of the dowel with a mallet. If it breaks up, you need to start again and cool a bit longer; if it sticks, you've waited too long, so hang the barrel muzzle-down and heat with the dryer or a VERY soft propane torch until the casting material melts and runs out - and cool down and start over. If you've got a gain-twist barrel (HA!), only do an inch or so at muzzle and breech, or you won't be able to push the cast out. Really easy, and very informative! floodgate