reconbob

You may have to go thru WayBack Machine but if you go to NFAToys.com the drawings you seek can be downloaded for free in pdf format. Bob

When I was in high school I had a part time job as a janitor. One night we had a job where we had to treat maybe 20 big wooden desk tops with oil that came in cans labeled “gun stock oil”. We used rags to coat the desk top with oil then dry rags to wipe off the excess. Half way through we figured we’d go get a snack. I neatly folded the rags on the wooden parquet floor in front of the elevators figuring any oil on the wooden parquet floor could be wiped off with no damage. 30 min later we get back and I go to pick up the rags and I burned my hand. You could see the heat waves shimmering above the rags. We must have got back just before they would have burst into flames. Prior to this I did not take the “oily rags cause fires” seriously but ever since I am very careful. Bob

Aha! Thanks! Bob

What is OOB! I can’t figure that one out? Bob

Yes, 8-40 is the thread. Thanks! Bob

The receiver has the prick punch mark on the top of the receiver just to the left and rear of the front. I thought that this was where the mark was made when a gun was rebarreled. I have seen receivers with two such marks meaning that they had had a second and third barrel fitted? Bob

Thanks - trying now. Bob

I don’t remember exactly but I think it sold for a little over $5000. Bob

I have a pitch gage. But the screws are so short you can only align the gage with maybe 3 threads and I can't tell for sure. I will do a test and tap a random piece of steel 8-36 and see if the screw fits. Thanks! Bob

Hello - I have the screws. I know the major diameter is 0.164" but the screws are so short there are only a few threads to check with a thread gage. This is a transferable West Hurley M1928 that previosly had the pop-riveted sight so I want to get it right. Bob

Does anybody know?. Bob

Do not remove the pivot plate. If you do, the sear, sear lever and trigger will not "drop down" because they all have springs which will push them up blocking the bolt. Usually this lock up is caused by the disconnector not snapping back under the sear lever when you let go of the trigger. Remove only the safety. Then use a punch or screw driver and reach into the safety hole and push the sear down. You will be able to depress the sear farther down than when you pull the trigger. If this does not allow the bolt to go forward report back. Bob

I have Doug's rivets. Pack of 20 for $15. Postage $8 = $23 Yes, I checked. They weigh less than 1 ounce but cost between $7.30 (near) and $8.75 (far) to mail. Best to email me at Philaord@aol.com. Bob

I go to NFAToys.com every week or two to check or get a drawing. It usually does not come up on the first try, but I eventually get there. Today after a bunch of tries and two different browsers it does not come up. Is it gone for good this time? Bob

Frank - I respectfully disagree with you rating this bolt damage/deformation as "quite common". I have had hundreds of Thompsons thru my shop for builds or repairs and almost never see this deformation. Years back I processed 900 used, torched Thompsons (Sarco project. This was long before 1986 and they wanted to reweld/build them into guns). The bolts were torched but the sear notches were intact and there was thought of rebuilding them. None of the bolts had this damage/deformation. I have bought and sold hundreds of used bolts and this damage is so rare (if it is military bolt) as to not exist. I am willing to be educated/corrected. Anybody who reads this and is willing to take the time, check your Thompson bolt and let us know if it has the damage/deformation shown in the photo above. Bob/Phila Ordnance

Thompson bolts and sears are very hard. Over Rockwell 60C. That is so hard a file will skid right off. While there is no danger here, I would stone the little ridges off so that the engaging surfaces stay smooth. At the minimum I would replace the sear, which might be $25. If you can afford it I would also replace the bolt. This wear is not normal. I have seen many many WW2 Thompsons that have many thousands of rounds thru them with the only wear being the loss of bluing. No deformation ridges as in your photo. In your first photo the loss of bluing on the trigger frame behind the sear is the result of the deformed ridge of the bolt scraping on the trigger frame which is not hardened and softer than the bolt. There is no way of knowing for sure why your bolt is deforming. Faulty heat treatment 80 years ago? Was the bolt exposed to heat somewhere along the way affecting its hardness? Another thing - when you shoot a Thompson you must fully and decisively pull the trigger. If you sloooowly pull the trigger to fire single shots the sear drags on the bottom of the bolt and the bolt will just nick the sear encouraging this deformation. If you want to fire single shots set the selector to single, and fully and decisively pull the trigger. Bob

Saw this on GB. I am no expert but I thought the M1921 bolts had a rounded recess in the back. This looks like the squared back of a 28/28A1 bolt. Or did they make M1921 bolts that look like this? Bob

I did quick check of a dozen stocks and I found one with this mark. This stock has the cross bolt, but no other markings. Bob

I have some M1928 stocks I will look closely and see if they have a similar mark. Bob

Yes, I saw that picture in a biography of Puller. I did not know the M1921 extractor was different than the M1928 extractor? Bob

I don’t think that is a stamped marking. M1928 stocks frequently have letters or numbers to match the parts for assembly stamped or marked with chalk on the stock under the buttplate, and on the inside of the buttplate and on the stock slide. But these marks are clearly impressions made by the stamps. On your stock the X is not an impression but the result of the surrounding wood being impressed and leaving a rough X as a result. Maybe this is an impression made by some tool or fixture to hold the the stock during manufacture? My $0.02 Bob

This is a clever fix, but I think could accurately be described as a blacksmith approach. If correct tools are not available I guess any port in a storm. I do not think it is a good idea to randomly heat a trigger frame red hot, because the line between heating and burning is a fine one. If the steel is over-heated or "burnt" it will become brittle. I have seen many frames like this that are so battered that I assumed it was not an attempt to remove the frame from the receiver, but an attempt to destroy or demilitarize the frame. A better safer fix is to clamp the trigger frame in a Bridgeport type mill as shown and use a standard 3/16" wide x 5/8" keyseat cutter. The T- slot in the trigger frame is 0.190" x 0.660" so frequently one pass thru the T-slot is all that is needed. Bob

Sears are as hard as files so any markings would have been done before heat treatment. Bob

This is a quality copy of U.S. Ordnance drawing "Thompson Submachine Gun, Cal. .45 M1928A1 Longitudinal Section". The original date of the drawing is December 31, 1941 with the latest update dated April 20, 1945. Full size 24" x 40". I found this in Doug's (Richardson) files. The drawing is of interest because there are no measurements or dimensions on the drawing. it is a cutaway view of a complete assembled M1928A1 Thompson, with every part indicated by an arrow with a leader going to the name and Ordnance drawing number of the part. Also of interest is that the M1928A1 Thompson depicted has a finned barrel, but an M1A1 rear sight with the triangular guards. The 28A1 Thompson was no longer in production in April of 1945 so who knows what they were thinking. This is a rare drawing because it has no drawing number and so does not show up in any searches of the archives. They moved most of the U.S. Ordnance technical archives to Picatinny Arsenal, and I know that not everything made it there. (For example - the drawing for the M1A1 Thompson bolt.) You can get drawings from the Data Release Officer under the Freedom of Information Act, but they search by drawing number, not name. My guess is back in the day Doug had his sources and was able to get this before it was lost during the move to Picatinny. I am selling fresh, new prints/copies of this drawing for $25. It gets shipped rolled up in a tube, not folded. Postage is $12.50. If you live in New Jersey it may be $1 less, if you live in California, it may be $1 more, but $12.50 for all. You can send check of money order made out to Robert Bower, and mail to: Phila Ordnance, 222 Roesch Ave, Oreland, PA 19075. Thanks Bob/Phila Ord

We have to remember that - except for a couple of oddball guns that had only a brief production life - the Thompson was the first submachine gun. And the gun designers were craftsmanship/commercial quality types who did not have simpler, later guns to copy or influence them. In those circumstances we get the one-piece, hardened steel grip mount. I also had never heard that the original pattern grip mount had a high breakage rate. Over all the many years I have been at this I have never seen a broken original pattern grip mount. But TD has put that idea to rest. Bob