drill receivers unsafe to build?

[DRB]

Being I Mechanical Enginneer, but not a metalurgist, I have had enough education on metalurgy to never trust a drill rifle. The heating during welding and cutting was uncontrolled and the cooling was uncontrolled. There is no way to say with certainty that they are safe. If one started growing headspace as it was fired I would suspect the locking surfaces got soft not that the receiver is stretching. This is the same issue that the National Ordnance receivers seem to have. Such a receiver is dangerous as excess headspace will lead to head seperations. The O3 drill rifles were welded on a lot what with the cuttoff and the barrel being welded then the barrel had a plug stuck in it and was torch cut on the bottom. I just do not think it is worth it since unmessed with 03s are not really that expensive and are much more likely to be safe. Now as to shortening an action I would say any good gunsmith who does that takes lots of precations that the locking surfaces do not get hot. On a drill rifle I bet a lot of nice red hot or hotter receivers rings did occur. Numrich used to make a .22 conversion kit for the 03. If you could find one of those I think you woudl be just fine shooting as many .22s as you wanted in a reactivaed drill rifle. Also let me say that if I were a gunsmith which I am not, I would not restore a rifle for a customer knowing that it was sold as unsafe. Only takes one blow up to put you out of buisness. I have some of the CMP MA unplugged drill rifles as well and would not consider firing them either though they have had a lot less welding done on them. My expectation on them is that with repeated use the receiver ring will crack at the weld. I do not think they got hot enough to ruin the heat treat on the lug seats but I am not sure some may have. The 03 and 03A3 receivers will probably eventually crack at the weld point on the receiver as well. So use at your own risk. FWIW I have sold nice unmessed with 03A3 receivers as recently as this year for $110. I have gotten more for them as well but they are around if you look.