I would think your gun, ammo, or accessory would have to be pretty hot to have it's radioactive contaminant detected by a geiger counter(which is the test it would have to pass in order to be a problem).
What?????
Are you suggesting that being able to be detected by a geiger counter somehow defines being "pretty hot" in some manner that not registering on a geiger counter would mean it could still be radioactive, but not pretty hot?
What is pretty hot? Do you mean to imply that "pretty hot" is a dangerous level?
Simply burning wood releases radioactivity. Do you have a compost pile? It is radioactive. At death, plants and animals stop intaking of carbon 14, an unstable isotope created by solar radiationing impact nitrogen 14 in our atmosphere. As the formerly living animal decays, the carbon 14 is realeased and the amount released can give some idea how long ago the animal was alive, starting about 100-200 years back to about 40,000 years for some of the less precise measuring equipment and back to closer to 100K for more precise measuring equipment.
Do you have tritium night sights? They are radioactive, only their radioactivity poses no risk so long as you don't break the little vials and breath the gas. Simple exterior skin tissue is enough to block it from entering your body.
Your microwave is radioactive.
Not all solar radiation is blocked by our atmosphere and it can be measured.
Lead is radioactive.
http://periodic.lanl.gov/elements/82.html It is a common shielding material to block stronger types of radiactivity.
Depression glass is radioactive.
Many things around us each day are radioactive and they can be measured with geiger counters.
Could military materials be radioactive. Absolutely, regardless of the country of origin. They would not necessarily need to be exposed to nuclear radiation tests to be radioactive. The decaying wood stock is releasing carbon 14.
The question is more of one pertaining not to if there is radioactive materials that we are buying, such as military surplus, but do said materials actually contain radioactive materials of the type and amount to be harmful to humans and if so, over what time period of exposure.
Keep in mind that we are surrounded by radiation. There is background radiaiton "noise" in the atmosphere and in the ground. It is hard to measure radiation at levels lower than the background noise, but it can be done to some extent with many controls added to the process. Just because something cannot be detected as radioactive does not mean it is not. Sensitivity settings for most commerical geiger counters will have their lowest levels or lowest useful levels set above background noise radiation levels.