Joe H
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Posts posted by Joe H
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JC556n,
Go to Kahr's AO website under parts. There is a blow up of the frame and details of each part. Click Frame Assembly Tab.
http://www.auto-ordnance.com/Parts/Thompson-T1.asp
The spring is a coil compression spring under the pawl. It keeps the pawl in the lowered position unless acted upon by the mag tab after the last round is fired using a clip mag.
As has been noted the spring may be missing or inoperable. IMO the the OE spring is too weak.
All the FCG parts in the trigger frame have to be removed to get to the spring.
Joe
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Anticus,
Thanks, it's a striker fired build. I maintained the blish lock & oiler. The selector lever was converted to a bolt hold-open.
Joe
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Anticus,
Very nice semi Thompson. I took a different route. I built my SBR semi using a Philly Ord 80 % receiver with the Colt 1921 engraving and a 1928A1 parts kit. Vert. grip from Deerslayer.
Joe
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Joseph,
I'm not sure you have any options on the 100% semi with Colt 1921 Markings. Reconbob (Phila Ord) posted recently that he did a trial run on 100% semi receivers and dropped the project for lack of interest. You could give him a call. IMO He would be the only possibility. D Richardson does not sell any 100% receivers. Last I checked Kahr will not sell a receiver.
If a licensed manufacturer builds one (100%) for you his name and address must be on it. IMO The only way you could get a 1921 Colt semi would be to build it yourself using a 80% receiver with colt markings. You could SBR it with your name and address on the frame or barrel.
My thoughts only. maybe somebody else has better options?
Joe
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dead-eye,
Here is the link about how to do the bolt hold open using the selector;
http://www.machinegunboards.com/forums/index.php?showtopic=5767&hl=bolt++hold++back
Recent discussion about using a FA frame:
http://www.machinegunboards.com/forums/index.php?showtopic=15584
The semi trigger and trip can be made by modifying the FA parts. The sear, disconnector and pawl have to be made from scratch or bought from Kahr.
Joe
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wjkw,
Remove the FCG (trigger, trip, disconnector & sear) from the FA frame. The safety lever is the same FA or semi. Keep the FA.
Using the FA pivot plate (it has three springs, the semi only has two) install the Kahr semi auto FCG (trigger, pawl, trip, disconnector & sear). If you use the Kahr pawl spring you will have to make washers to make up for the difference in slot thickness or you can use a torsion spring. I would not plug the selector hole. Just modify the semi parts to clear. The selector will turn but do nothing. It can be converted to a hold open later if you desire.
Having the selector switch and FA pivot plate IMO is the main reason to use the FA frame.Otherwise it will loook no different than the Kahr semi frame.
Joe
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Wykw,
To use a FA frame on a Kahr semi-auto upper you will have to make a milling cut (or grind) on the front of the FA frame to fit on the Kahr reciever. Slide the FA frame on the semi -auto reciever and it's pretty obvious what has to be removed. It's a very simple cut. You also have to mill a slot for the sear tab on the semi-auto. You can see the location of the slot on the Kahr frame.
You will notice the well in the Kahr frame is narrowerer than the FA frame. That is so the FA FireControlGroup cannot fit in the Kahr frame. By plugging the back right corner of the FA frame well with weld you can prevent insertion of a FA sear in the FA frame.
All the semi auto FCG parts will fit in the FA frame without modification and operate properly on the FA pivot plate shafts. However, if you want the FA selector switch in place, the pawl, disconnector, and sear must be milled or ground ( the sear is hardened) for the parts to clear the selector switch shaft. If I remember correctly washers (about 1/8" thick) have to be added on the shafts to make up for the different well widths between the Kahr & FA frames.You can modify the selector switch as a bolt hold open device.
http://www.machinegunboards.com/forums/index.php?showtopic=5767&hl=bolt++hold++back
If you are looking for an offical approval letter from the ATF you won't find one.
Joe
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Paladin,
The kahr uses 2 bolt return springs and single spring for the striker. You maybe could combine the 2 return springs into one. For a striker fired semi you need 2 springs (or groups of springs) one for bolt return and one for the striker.
For a hammer fired semi you use the original spring as a bolt return spring and an AR type hammer fired FCG. This system has the hammer and hammer spring in the fire control group. There is only one spring on the bolt.
Any FA open bolt MG only requires the spring to close the bolt. The gun automatically fires when the bolt closes. The semi must fire from a closed bolt (ATF) so it needs a separate hammer or striker operated by the trigger to fire.
Joe
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I was experiencing problems with the extractor slipping off the bolt and jamming the gun. To sove the problem they "pinned" the extractor to the bolt by drilling a small vertical hole through both and inserting a metal pin to hold the extractor at the rear of the extractor.
Yes they did fix your issue. They didn't fix the problem. Either the extractor or the bolt slot for the extractor was out of spec. They should have replaced whichever one was. Now do you have to drill the pin out to replace the extractor? Maybe I'm too picky but it's not my idea of a proper repair. Just my .02 cents.
Joe
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Bob, as someone who has finished your receivers for a long time, they are great, don't know where we'd be without you, but I know we'd have a lot less display guns and post samples out there.....
Thanks
Dan
Ditto and add semi-autos. I've built 3 using PO receivers.
Joe
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Embalmer,
I agree with Chris.
Did it work ok before you installed the EZ springs? If I remember correctly the EZ springs add a buffer which shortens the rearward travel of the bolt. Even though it locks when you pull it back by hand the slot in the bolt that the pawl locks into may present itself to the pawl for too short a time (during actual firing) for the pawl spring to push the pawl up into locking position. An increase in bolt travel length may solve the problem. You may notice a nick on the end of pawl slot on the bolt where the pawl is trying to lock. IMO the Kahr pawl spring is too weak and should be replaced with a stronger spring which also may solve the problem. It could also be the mag spring so try another mag.
Troubleshooting:
Taking out a return spring has nothing to do with your problem.
If it worked ok before the EZ spring installation take out the EZ spring buffer and try it. If it works without the buffer then what I said above may be true and I would try another mag and if that doesn't work replace the pawl spring with a heavier spring as the buffer is needed for the EZ spring.
I doubt it has anything to do with the mag if it worked without the EZ pull. To check it, remove the trigger frame from the reciever and place the stick mag with 2 rounds in it in the frame. Observe the pawl, it's the little arm on the right side of the fire control recess. With one round out it should be flush or below the surface of the frame. When you slip out the last round it should pop up about 1/8" above the frame surface.
Joe
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Fxdrider,
Green Mountain makes excellent Thompson barrels. They are all made to military FA specs. The guys over at this site are very pleased with them:
http://www.weaponsguild.com/forum/index.php?board=105.0
You will find a couple of threads discussing the 14.125" Tommy barrels. They must be used with a permanently installed compensator (that is permanently installed per ATF specs) or a SBR tax stamp is required. IMO opinion they look best on a Tommy with a vertical foregrip like the 27A1. IMO any barrel over 10.5" just doesn't look right with the horz foregrip and particularly the M1 with the smooth barrel & no comp. Just my .02 cents.
Joe
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Guys,
A few comments from my experience regarding Reconbob’s and Schatzperson’s discussion on API. I’ve built Thompson closed bolt semis using original parts kits and Philly Ord receivers. The 1928A1 semi design included the original Blish lock. The M1 was a straight blowback. Both worked fine using light return springs similar to the EZ Pull springs. With the heavy recoiling parts of the 1928A1 and M1 I’m not sure the blish lock makes any difference nor does the lack of API in the semi auto closed bolt. In the book referenced by Reconbob “Engineering Design Handbook for Automatic Weapons” a design example of a straight blowback .45acp is given. The example is surprising, well maybe not, similar to a 1928a1 or M1 Thompson. In the example the weight of the bolt is identical to the M1 bolt and the 1928 bolt plus actuator (recoiling parts). The weight of the bolt is all that is required for the blowback design.
I agree with Reconbob that the 1921 Thompson is a different “animal”. The recoiling parts are lighter and consequently the rate of fire is double the 1928 & M1. I strongly suspect that the 1921 does actually employ the Blish principal to delay the opening of the bolt. It may also use API. I doubt just the weight of the “recoiling parts” would pass the design example mentioned above. As far I know nobody has built a closed bolt semi utilizing the original 1921 bolt & actuator. My guess is that it would need very heavy springs like the current Kahr semis. From all accounts the current Kahr semis work well with the EZ pull spring kits.
The 20mm Orelikon was designed using API. It is not a locked bolt and uses a heavy bolt and huge springs. If you tried it as a closed bolt semi it would surely blow the case.
My .02 cents
Joe
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fxdrider,
You can use a FA trigger frame on a W/H Kahr Semi Auto. You will have to make a milling cut on the front end to match the Kahr reciever. Other than that, it will fit. All the semi internals will fit in the FA frame but will not clear the FA/SEMI selector shaft. The sear, pawl & disconnector must be modified to clear the selector shaft which is not present in the Kahr semi frame. The recess must be plugged in some way so that a FA sear will not fit in your frame.
D Richardson expains the process in his book on Semi - Autos.
http://www.thompsonsmg.com/HOME_PAGE.HTM
This site may be of interest:
http://1927a1.com/thompson/mods.htm
Joe
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Sarge,
There are two parts that could prevent the frame from being removed. One is that the bolt is cocked and the firing pin sear tab is engaged on the sear. If you try to remove the frame you should feel spring tension if the bolt is cocked. The other is that the pawl is jammed and is bearing on the slot in the bolt. The pawl holds the bolt open after the last shot. It is activated by a tab on the box mag. You can see the lever at the top of the mag slot. Try pushing it. There should be spring tension pushing back if it is operating properly. It has a very weak spring.
Possibly the trigger could be jammed as a result of trying to put on the safety with a closed bolt then trying to open the bolt.
If all else fails the only way to remove the frame is to remove the pivot plate. This will unlock all the internal fire control parts. Then it becomes a very frustrating experience with a small screwdriver and/or ice pick to jiggle the internal parts so that the frame can be removed.
Joe
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Sarge,Maybe you are missing the obvious. If the gun is cocked you won't be able to strip off the frame and there will be spring tension on the frame. You said that if you leave it go that it slides back to start position. Be sure it is unloaded, pull the trigger and then try to dis-assemble.
Joe
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Zeeone,
I'm assuming your are not trying to drive the sear tab over the sear. I don't have the AGI video.
If it is just tightness in the slides (poor dimension control from the factory) and not any other mechanical binding, as noted by Sandman, it can be corrected by using a little lapping compound. Put the compound on the slides and slowly work the slide off and on, a little bit at a time. The compound is abrasive and will remove those last couple of ten thousands that are causing the binding. I've used Timesavers green for this type of work. It's a fine powder you mix with oil. You can mix it very thin for the initial tries. The other advantage of Timesavers is that it will eventually stop cutting, regular lapping compound will not. In either case be sure it is completely removed when you have completed the lapping.
Joe
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ReconBob,
"Thompson bolts are quite hard. The pdf you provided does not have the heat treating
specs but the ordnance drawings specify the hardness using the C scale and the range
for all surfaces of the bolt is Rockwell C 62-70.
This is quite hard - too hard to file or machine with hardened steel tools or even tungsten
carbide."
Remember this discussion:
Not nearly the 62 RC specified.
I've machined both 1928A1 and M1 bright bolts without annealing. Neither were anywhere near 62 RC. I had no problems using carbide tooling and in one case milled a slot using a vintage B&S HSS slitting cutter.
The M1 bolt required deep (3"+) 1/4" dia holes and deep thick slots.
Joe
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I plan to do all of the work myself, just like I do on my cars. I have a hard time justifying paying someone else to do what I can do on my own. Knowing the time it takes right now for a stamp I'm not in a rush for anything, but I'm in the market and may pick up a few to compare and look at in person before starting paperwork. I'm not in a rush, but definitely don't want a 16" barrel.
Eagle,
I have to agree with everyone else. IMO unless you are able to build one from a parts kit & 80% receiver and you want a semi that looks as close as possible to the real thing, get a 1927A1 and SBR it. Using a GI trigger frame is a great plus. As GIO mentioned D Richardson's Semi book shows how it's done. It is not that difficult, milling cut and milling or grinding some FC parts to clear the selector switch. Nothing in the world of "Thompsons" is cheap including the semi's. Give some thought to what you are really looking for.
I agree on the barrel length, the barrel lenght on the 1927A1 is bad and looks worse on the M1. Green Mountain Barrel makes a finned Tommy barrel that is 14+". With the compensator permanently (see ATF NFA Handbook) installed it is 16" , 2" shorter than the Kahr 16" barrel + 2"+ of compensator. It doesn't look too bad on the 1927A1.
Unless you are building the SBR from parts you must have your rifle's serial number to apply for a Form 1 SBR . I got one last Oct. It took 6 mo. I've heard current number is 8mo.
Joe
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what is the going rate for this item? Post-Dec 2012? i can post pix if you all like. also could i install some old wood from, say, a 1928 model and save my originals? I know the buttstock is bolted on rather than "slide on rail." so i may need to drill a few hold in an old stock. i'm not going to change the barrel length.
FM,
I sold a W/H in 2010. Good shape, 1 - 30rd clip mag, no case, Round cocking handle, EZ pull springs on GB for $775. Fits in range David quoted above. Except for the recent craziness Kahr/ W/H's resale prices have been pretty stable. Pic below.
A 1928A1 buttstock won't fit the typical W/H Kahr. An M1 buttstock probably will.
Joe
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A original wood set would really make that thompson POP. Just my thought.
Ryan
jhm,
I no longer have my W/H semi so I can't be sure, but there is a high probability that the military M1 butt stocks( not the 1928A1) will fit the W/H Kahr rifles. The horz. forearm ( M1 & 1928A1 are the same) may have to be modified a little if you have the 3/4" gripmount (military is 1/2"). N/K had a large stock of Thompson military FA parts when they introduced the Semi so a lot of the non fire control parts are interchangeable with the military version.
Hopefully someone will chime in who has made the conversion.
Joe
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Actually the Kahr and WH springs have the exact same OD. The difference is wire gauge. The .006 smaller wire of the original springs makes the ID .012 larger.
I was looking at spring weight comparisons. I was surprised that the recoil springs each have more "rate" than the much larger firing pin spring. Larger OD and larger wire diameter makes for a spring with about half the force. Isn't bigger always supposed to be better?
Learn something new every day.
As far as springs go, spring performance depends on a lot of factors such as metal used, diameter, method of manufacture, heat treating. Did you measure the force of the recoil springs and the firing pin spring? Keep in
mind that the firing pin spring also doubles as a recoil spring--it is just not called that.
Guys,
If you don't have it already and are working with springs this site will give you pretty much everything you need to know:
http://www.planetspr...?id=compression
Most springs used in firearms like the Thompson are made from music wire. Allow about .010" dia clearance between the guide / hole and the spring.
That "firing pin" / "return" spring on the W/H Kahr is identical to the FA TSMG 1928A1 spring only shorter. Not surprising, since when N/K introduced the semi they had a large stock of FA parts from their purchase of Auto Ordnance.
Joe
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I ordered several extractors so I'm going to try that. I also have some high-durometer Sorbothane on the way and am going to experiment with springs. i contacted Deerslayer and he's no longer selling his spring/buffer kit. I know I'll piss away $80 worth of time but I have a tough time coughing up that much for 30 cents worth f plastic and $8 worth of springs.
CTS,
Check your PM's.
Joe
Bolt wont lock back on last shot
in Thompson Semi-Auto Discussion Forum (West Hurley & Kahr Semis)
Posted · Edited by Joe H
I built a semi using the Kahr FCG. I had a similar problem. My problem was the slot I milled in the bolt for the pawl, but I doubt this would be a problem in a production gun. I did have a Kahr semi and the one thing I noticed was that the original equipment pawl spring was very weak. I had to use a much stronger spring in order to set up a bolt hold open device that would work properly.
IMO the first thing I would do would be to replace the pawl spring and maybe be prepared to use a stiffer spring.
My .02 cents
Joe