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Special order Winchester M75 Target Rifle
December 20, 2015
1:26 am
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Recently I bought a M75 3 digit # 837 with a (38) bbl. date. The rifle came with Vaver sights that were available from the factory back then.

Now all collectors know, that all M75’s are D&T’d at the factory for the standard thread that fits the Lyman and Redfield series sights. Sights can be changed to suit the individuals needs.

Not so with the factory installed Vaver rear sight, # 3675. It has an oddball size hole for a 6-44 threaded screw. A little smaller than standard. A standard Lyman or Redfield will not fit.So, all this means if you happen upon one of these very scarce Vaver sighted rifles, and want to know if they are in fact, factory, look for the smaller holes with the 6-44 thread.

Just a little tidbit of info for those who are M75 collectors such as I am.      Big LarrySmileSmileSmile

December 22, 2015
5:12 pm
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BL, The thread size used by Winchester and most all other manufacturers to mount the sight bases & scope blocks is a 6-48. The 6 represents the screw size diameter, in this case .138″. The next number is the pitch or tpi, or threads per inch. A 6-44 would have the same diameter screw as the 6-48, and the only difference is the thread pitch, i.e., 44 threads per inch. To the casual eye they would look identical in both diameter and pitch. Both of these threads are regarded as a “special”.

   Are you sure the Vaver rear base requires a 6-44? There is no mention of this on the model 75 Winchester blueprint. It just lists the 6-48 size. Also, the Vaver catalog states that the mounting base for the rear sight on the model 75 uses “factory” holes on receiver for mounting.

Just wondering???

Steve

December 22, 2015
5:50 pm
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Hi Steve. Yep, they are 6-44’s. They were both sheared off when I received the rifle by the USPS. No damage to the box. I have lots of 6-48’s for my Lymans and Redfields and they didn’t fit, so I sent the broken screws to Jeff to make me a new set and he could not do it as they were, in fact, 6-44’s. I have a custom made set coming today, if I am lucky, and will get this project done. I am quite sure this rifle was special ordered due to the Vaver 6-44 receiver holes. This sight combination on a M75 is quite rare. I have never seen another, or even a loose Vaver-Whittek #3675. This combination was listed in the 1st year books as a G 7527R. # 837 has a (38) dated bbl.

Now, my 1940 BULLGUN came with  Vaver sights, and the books states will fit standard Winchester D&T holes and it does.

Strange deal here. None of these M75’s around to make a comparison. I can assure you, the holes have not been re-tapped. Thanks, Big LarrySmile 

December 22, 2015
11:21 pm
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Hi Steve,

I found it very strange also, I have never heard of a 6-44 used on a Model 75 and it certainly is not detailed anywhere I have seen or mentioned on the drawings. 

The screw pieces Larry sent me were definitely a #6 size and measured at .137″ but would not thread into a 6-48 screw gauge.  I measured the pitch at 44 with a thread pitch gauge and it is certainly possible I could have made an error due to the small size of the screw but visually the threads seemed to be coarser than 48 and finer than 40 when compared side by side to a 6-40 and 6-48 screw.

I have no idea why they would have deviated from the standard 6-48 as it makes no practical sense to me.  I would think the difference in shear strength between a 6-44 and 6-48 would be negligible.  I also doubt they would have matched the 75 receiver threads to an odd-sized screw supplied by Vaver as that does not make sense from a production standpoint either.  

Regardless, Larry had a problem matching them and could not get a 6-48 to fit so I am really curious if the 6-44 screws will work or if there is another underlying issue.

Larry, I will make up a set of 48 pitch screws with a slightly smaller diameter of .135″ and send those to you to try also.

Best Regards and Merry Christmas to you both.

Jeff

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December 22, 2015
11:40 pm
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Screws, 6-44 type, were scheduled to be delivered today, but did not make it. I hope they didn’t get lost. They show as never leaving Memphis, but to be delivered today. Not here yet. This whole event has been a fiasco from the beginning. As soon as they arrive, I will let you guys know if they work. Thanks, Big Larry

December 23, 2015
12:04 am
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Hi Larry,

I just edited my post above but will repeat it here;  I will make up a set of .135″-48 pitch screws (slightly smaller diameter than a standard #6) and send them to you in case the 6-44 doesn’t work either.  It is feasible that your receiver holes are on the small side (I could not find a +/- tolerance for the .140″ receiver threaded hole) and that could be why your standard Lyman and Redfield screws won’t start.  It seems like a slightly undersized 6-48 hole is more likely than an odd 6-44 size.  It is worth a try at least. 

Best Regards,

WACA Life Member #6284 - Specializing in Pre-64 Winchester .22 Rimfire

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December 23, 2015
1:46 am
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Thank you my friend.   Big LarrySmileSmileSmile

January 3, 2017
8:21 am
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seewin said
BL, The thread size used by Winchester and most all other manufacturers to mount the sight bases & scope blocks is a 6-48. The 6 represents the screw size diameter, in this case .138″. The next number is the pitch or tpi, or threads per inch. A 6-44 would have the same diameter screw as the 6-48, and the only difference is the thread pitch, i.e., 44 threads per inch. To the casual eye they would look identical in both diameter and pitch. Both of these threads are regarded as a “special”.

   Are you sure the Vaver rear base requires a 6-44? There is no mention of this on the model 75 Winchester blueprint. It just lists the 6-48 size. Also, the Vaver catalog states that the mounting base for the rear sight on the model 75 uses “factory” holes on receiver for mounting.

Just wondering???

Steve  

JWA said
Hi Larry,

I just edited my post above but will repeat it here;  I will make up a set of .135″-48 pitch screws (slightly smaller diameter than a standard #6) and send them to you in case the 6-44 doesn’t work either.  It is feasible that your receiver holes are on the small side (I could not find a +/- tolerance for the .140″ receiver threaded hole) and that could be why your standard Lyman and Redfield screws won’t start.  It seems like a slightly undersized 6-48 hole is more likely than an odd 6-44 size.  It is worth a try at least. 

Best Regards,  

<br /

Just going over old posts and found this interesting quandary. Was there ever a solution to the question of correct screw thread?

Vince
Southern Oregon
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 “There is but one answer to be made to the dynamite bomb and that can best be made by the Winchester rifle.”

Teddy Roosevelt 

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January 3, 2017
12:09 pm
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Vince said 

 

Just going over old posts and found this interesting quandary. Was there ever a solution to the question of correct screw thread?  

Hi Vince,

I made a set of smaller diameter (.135″-48) screws for him but they still did not work.  The working solution for Larry was to use custom made 6-44 screws to remount the Vaver (which was broken off during shipping).  They threaded easily into the existing holes whereas a 48 tpi screw did not.  It is the only Model 75 I have ever seen that did not use 6-48 screws for the rear sight. 

As Seewin has mentioned there is no reference of 6-44 used on the Model 75 receiver in any of the existing material I have seen either nor can I imagine a reason to even deviate from the specified 6-48.  The screws that came with Larry’s 75 were in fact 6-44 (I measured them several times to be sure) but whether they were original to the gun or just forced into a 6-48 hole we may never know.  It is now another thing on my radar to be alert for while doing future research on the 75.

Since the screw pitch mystery is still unsolved I agree with Larry’s solution to just remount the Vaver  with 6-44 screws instead of re-tapping the holes to the standard 6-48.  Better to leave it as-is until there is a definitive answer.  It would be interesting if others with the Vaver sighted Model 75 (catalog G7527R) would measure their screws but so far no one has as mentioned they have one for comparison as they are fairly rare.

Best Regards,

WACA Life Member #6284 - Specializing in Pre-64 Winchester .22 Rimfire

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January 3, 2017
4:48 pm
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The 648 screws were to big to even fit the hole. The factory holes were indeed 644. I had a set made by Simmons Custom Services, which by the way, was no easy task. The screws then fit perfectly. Evidently, the G7527R, is a very scarce, maybe even rare, rifle. With an low # 837 and a (38) bbl. date, it has to be one of the first made. I don’t know why they used the 644 screws, but if the factory hole was too small for a 648, it has to be factory. It could be made bigger, but not smaller. The Vaver 3675 was made for the M75. They also made them for the M69 and M72 as well as a few others. Very seldom is one of these sights seen for sale. They are not marked and that adds to further confusion, 3675-Vaver.jpgImage Enlarger In my collection of M75’s, I have all the listed variety’s and # 837 is the only one with 644 screws. Even my G7501R, #282, has 648 screws, so just because it is an early rifle, that has nothing to do with the screw size. JWA has first right of refusal on this rifle should I break up my collection.   Big Larry

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January 3, 2017
10:42 pm
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Big Larry said
The 648 screws were to big to even fit the hole. The factory holes were indeed 644. I had a set made by Simmons Custom Services, which by the way, was no easy task. The screws then fit perfectly. Evidently, the G7527R, is a very scarce, maybe even rare, rifle. With an low # 837 and a (38) bbl. date, it has to be one of the first made. I don’t know why they used the 644 screws, but if the factory hole was too small for a 648, it has to be factory. It could be made bigger, but not smaller. The Vaver 3675 was made for the M75. They also made them for the M69 and M72 as well as a few others. Very seldom is one of these sights seen for sale. They are not marked and that adds to further confusion, 3675-Vaver.jpgImage Enlarger In my collection of M75’s, I have all the listed variety’s and # 837 is the only one with 644 screws. Even my G7501R, #282, has 648 screws, so just because it is an early rifle, that has nothing to do with the screw size. JWA has first right of refusal on this rifle should I break up my collection.   Big Larry  

Larry,

You are still not understanding what Steve (Seewin) has stated.  A 6-44 screw and a 6-48 screw are identical in diameter.  The only difference between a 6-44 and a 6-48 screw is the Pitch diameter.  The Major and the Minor diameters are identical.  Therefore, a 6-48 screw cannot be “too big” to fit in the hole.  It is simple the wrong thread pitch (too fine) to allow it to start threading into the 6-44 tapped hole unless it is forced (cross-threaded).

The only reason that makes sense to me for why your rifle was D & T for a 6-44 screw is that it was special ordered with that sight, and the person who installed it was diligent enough to measure the screws before tapping the holes for it.

Bert

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January 4, 2017
1:36 am
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I agree Bert. The 648 screws would not start into the provided holes. We are very confident this was a special order as there appears to be very few, if any, around. The original screws were broken off in shipment. Pieces were sent to experts on these things as I tried to screw in 648’s and they would not go. The gentleman that made new screws for me, that fit, told me in fact, they were 644 screws and very seldom used nowadays. Vaver was one of the best sight makers in his day. His bases for the front sight were particular only to his globe front sights. That appears to be true on the M52’s as well. The M52 rear sights are D&T’ed for the 648 screws, or at least my two are. It is a very interesting fact, that the rifle did come with 644 screws. The 644 screws that were made special for me, screwed right in. This is a weird situation, but no one else seems to have a Vaver sighted M75. Thanks, Big Larry

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