Looking for name and number of the gun doctor. I have a perazzi TMX that opens up with heavy loads.Put all new springs in and it didn't help.Does anyone have this problem and has anyone had work done by the gun doctor.
MIA, I'm sure, heard it from me. To state a fact, 4 top levers broke when I predicted they would. On those 4 occassions, the shooters came to me and said their guns where popping open. I told them to NOT shoot their guns, because the chance of snapping off the peg at the bottom of the top is greatly increased.
At the end of the day (one was a couple of days later at the WI ST SHOOT) they came to me with broken top levers.
Something very similar happens with the Rem 90-T. The bolt actuator (dog bone shaped part) will break if the top lever pops open.
Here is my theory....That little peg and bolt actuator doesn't have a whole lot a pressure applied to it when operated manually. It just pushes and pulls on the locking bolt. During the firing of the gun, the bbl lugs grab hold of the locking bolt and keeps it from moving....at least it's suppose to.
If the locking bolt and/or the bbl lugs are worn enough, the locking bolt's job of applying pressure to the lugs is diminished. Two things may or can happen. One is the locking bolt is jumping from the bbl lugs the very instant the recoil stops against the shoulder. Exactly the same way an inertia block reacts. Add a weakened top lever spring, and it moves more freely.
The second possibility, is that during the recoil, an improperly fitted locking bolt gets pinched or pried out of the bbl lugs.
Either one of the above puts extreme pressure on that tiny little spot on the top lever. The locking bolt acts now like a hammer, beating against that peg.
During the early production years of the 90-T, before the 8 degree bolt angle change, installing a new bolt actuator was a common and very frustrating period of time. Shooters were coming to Kolar with guns popping open or top levers not working (broken actuator). Through a lot of experimenting, the bolt angle and bbl lug angles were change from 10 degrees to 8 degrees.
With the properly fitted 8 degree set up, a top lever spring was not even needed to keep the gun closed, because the two angles..bolt and lugs, were so close to a locking taper.
The original 10 degrees (90-T)was copied from an early Perazzi TM-1. Most of the newer guns (MX series)now have a lesser angle, 8-9 degrees. Those that come into the shop, either the TM-1 or MX's, I check the angle of the bbl on the comparator. If it's at 10 degrees, I recut them to 8 degrees, then rebuild and grind the locking bolt to the same angle.
Whiz, as long as we're on the subject of locking bolts, your friend in Italy stated that the locking bolts he furnishes are ion nitrided (similar to case-hardening), to make them harder than the bbl lugs. I kind of question the reasoning behind that. From my point of view, wouldn't it be better to have it equal to, or maybe slightly less hard than the bbl lugs? Reason being is, if at some point something needs to be welded, isn't it easier to weld the locking bolt. I've welded a lot of bbl lugs, and it's truly a lot more work squaring everything up and then cutting the angle. I'd rather continue welding the bolt (or replacing it), and letting it wear a bit faster, until the point the bbl lugs need to be welded.