In 1998, my wife, Dana, and I began our journey to Thompson land with the purchase a West Hurley Model 1928 for Dana as a very symbolic but politically incorrect Valentine’s Day Present. It shot beautifully, but that was due to a minor modification by the previous owner. The owner did a beautiful job of machining the ears off the Blish lock. I didn’t worry about this since Tracie’s book showed an Aussie mod that negated the Blish, and both the M1 and M1A1 versions have no Blish. Ah, blissful ignorance.
At our first shoot (1998), I believe it was Chris Martin who told me I couldn’t put the pieces back together that way. I said I could because this Blish lock doesn’t have any ears on it. I won the battle, but Chris won the war (and he was a gentleman about it—thanks Chris). He pointed out the M1 and M1A1 versions had a thicker rear area and a different buffer to absorb the shock the Blish would have dissipated, and, by the way, that is why the fiber washer is disintegrating. Game, set, and match to Mr. Martin. A couple of weeks later, MJ and Chuck Klein sent us a new Blish lock with ears intact.
The new Blish worked beautifully, but the gun started to hiccup on a regular basis. Was it my reloads? OK, I admit most of them didn’t gauge, but…. Anyhow this keen eyed gunsmith who after 40 years turned his Colt Commander into a reliable weapon, took action. I contacted Tracie and got a couple of things to check—nicks on the Blish and burrs in the Blish’s locking channel in the receiver. Those turned out to be negative. Finally, I noticed light hits on the primers; also Bob Hardy had a similar problem. Bob had fixed it with a new recoil spring. While old parts are generally superior to the new ones, I look at springs as an exception to this rule.
The following paragraphs of this article can be regarded as a commercial for Wolff
Springs. In a former life, I was an IPCS shooter (until I shot a machine gun). Regardless, Wolff springs were considered to be the best. Off to their web page—Yes! They have recoil springs for every Thompson model and now they make springs for 30 round Thompson magazines. A good pair of wire cutters can create a twenty round magazine spring.
A couple of days later, the springs arrive. Success? Not quite. Three times I installed the new spring, and three times I had to untangle a mess. Sugar and WTF. Then I remembered the old verses new rule, dug around, and found an old spring guide. It was only a quarter of an inch longer. Will it or won’t it? Yes!!!!!!!! Surprisingly, the kinking didn’t do any damage to the spring—a victory for modern spring technology.
How did it shoot you ask? Well it shoots beautifully, and there was a surprise bonus. (It is still shooting beautifully after 5,000 rounds and five years) Please excuse a slight digression to my IPSC days, but I think the theory is applicable to the Thompson. There are two ways to assess a recoil spring. The first is how far does the ejected casing fly? Four to six feet is the typical distance. Test one passed. Now for the surprise, in double tapping an IPSC gun, a spring that is too weak will leave the second shot higher than the first. In other words, the spring leaves the recoil energy with slide rather than absorbing it, which causes the gun to jerk upward when the slide hits the rear stop. By the same token, a spring, which is too strong, will absorb much of the recoil and eliminate the upward jerk, but will slam the slide home harder (jerking the gun downward instead) causing the second shot to be low. While this is not a totally correct explanation, it’s close enough for government work—oops, I just gave my pre-retirement employment away. A double tap is roughly equivalent to automatic fire; hence, that’s why I feel the theory is valid for the Thompson. The West Hurley used to print a vertically rising group, but now it sits there and chews up the bullseye.