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West Hurley Rear Sight Question


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#1 TD.

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Posted 17 June 2004 - 10:27 PM

How much trouble is it to swap a West Hurley rear sight for an original Lyman rear sight? Do the holes line up perfectly or is some drilling (and tapping) required? I would be interested in hearing what all is involved with this process including any negative aspects of this conversion.
Thanks

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#2 PK.

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Posted 17 June 2004 - 10:46 PM

It all depends on how your receiver was prepared. Some WH guns have the mil spec holes and countersinks, others the right diameter holes but commercial countersinks, others are tapped for screws. The hole spacing is constant among all available Thompsons, including new production.

Lyman sights are expensive and messing with their holes chafes me. I make special rivets to adapt the Lyman to the particular receiver and preserve the integrity of both parts.

The Lyman sight is better than the knock offs, but in actual SMG shooting, I find the M1A1 to be a superior sight. In the semi application the Lyman will be a fine addition.

To do the job right, special tools are required to set the rivets from both sides simultaneously.

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#3 The1930sRust

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Posted 18 June 2004 - 05:36 AM

I did a lot of research on this, mainly off the old boards, and decided it was very complicated! It seemed simple to me but, als PK stated, getting the proper rivets is critical.

When I sent my Thompson to Paul for work, I had him attach a Lyman.

user posted image

He threaded the Lyman holes and used screws from up inside the receiver...

user posted image

I suppose it minimally altered the original Lyman sight, but it is easy to remove (which will come in hand during upcoming reblue procedures), and could be reattached with rivets with no sign of alteration.

Just a thought...
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#4 TD.

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Posted 18 June 2004 - 06:55 AM

Paul & Chris - Thank-you for your replies. Great pictures!!!

Paul would be my choice of gunsmiths to perform this conversion too!

I do have a couple of more questions:

1. Did any of the West Hurley production Thompsons (not the NACs or parts guns) come with Lyman rear sights? I wonder if these may have been standard on the early WHs or available by special order.

2. Does anyone make a Lyman type sight insert or ladder that can be installed in the WH sight base? I have never heard of this type accessory but it seems like a market would exist for this type of upgrade. I assume the Lyman sight (without base) would not fit in the WH sight base.

Thanks

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#5 PK.

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Posted 18 June 2004 - 08:09 AM

The first WH guns had Lyman sights assys. When these ran out, a new base made of light alloy was used with origanel Lyman staff assys. When the Lyman staff assys ran out they were substituted with other surplus rifle staff assys and finally, those of their own make.

An original Lyman staff assy will fit into any of the after market bases used on WH or Kahr guns (minor fitting may be required). I know of no new mfg replacement for the Lyman staff assy.

Chris and I selected the screw from the bottom format with his sight because he wanted to insure that the Lyman could still be attached to another gun via standard rivets. By tapping the base holes, they retained the minor diameter needed for use with such rivets and any subsequent attachment of the sight would not fall out of the ordinary. This system also allows the attachment of accessory bases to replace the Lyman with about any other sighting device that might be desired.

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#6 Sgt

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Posted 18 June 2004 - 09:04 AM

PK-- Did you have to do anything to keep those screws from coming loose? I know that this must be a critical concern, since they are inside the receiver.
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#7 Motorcar

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Posted 18 June 2004 - 09:59 AM

PK!

I didn't mean to "chafe" you when I sent you the 27 and Lyman sight for installation! ohmy.gif
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#8 PK.

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Posted 18 June 2004 - 12:21 PM

Motorcar- not to worry; I have plenty of talcum powder. wink.gif

I install a lot of Lymans on 27a1’s and have no problem doing whatever the customer desires (within reason), but prefer to keep the sight with the issue 1/8” holes and make changes in the rivets, as required.

Sgt.- Because the heads of the screws match the countersinks and all else is held to a good fit, Loctite works wonders. Most folks don’t realize that the angle is different for metric and American standard flat head screws. The screws Kahr uses don’t even come close to matching the countersinks in their base. If you don’t have surface area, you got ‘nothin to hold.

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#9 TSMGguy

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Posted 18 June 2004 - 09:32 PM

P.K.:
Noted your reply above about the superiority of the M1A1 sight. I've never shot one. Would the "L" sight be just as good, except without the protective "ears"?

Do certainly like the adjustability of the Lyman sight on the '28A1, but find that I don't use it much.

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#10 PK.

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Posted 18 June 2004 - 09:43 PM

Howard,

The L has a more rounded top and doesn’t “frame” the aperture as well for me, but still better than the Lyman for burst fire.

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#11 TD.

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Posted 21 June 2004 - 08:15 AM

This is a great post on the West Hurley to Lyman rear sight exchange. Thanks to everyone, especially PK, for all the information posted. Staff Assembly - those were the words I was looking for smile.gif

Chris, this may be good information for inclusion in the FAQ section.
Thanks again,

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