Tapping 12 g. Tru-Choke thin wall problems
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  1. #1
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    Default Tapping 12 g. Tru-Choke thin wall problems

    I have several shot guns that use Tru-choke thin wall chokes and recently ordered the reamer and tap to install these in a double barrel shotgun. I read their instructions. Reaming the barrels went fine. I tapped the barrels and that went ok. I tried to install a choke and it turned a quarter turn and stopped. I was looking at the tap and it stated that it is a .775 44 tpi 2 start tap. I think they sent me the wrong tap since the choke tube uses a single thread. the retailer is telling me that the tap is correct. I talked to a machinist that told me a 44 tpi 2 start tap uses to 22 tpi threads for a total of 44 tpi which means the choke is not compatible. I would greatly appreciate feed back to to help clarify this information. In the mean time I have a ruined shotgun. Thanks.

  2. #2
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    Who is the retailer?
    I don't know about choke tube threads, but a 44 tpi tru-choke going about 1/4 turn into a 44 tpi 2 start sounds plausible.
    Who is the retailer? Did you buy new chokes with the tap? Maybe that retailer sells chokes compatible with that tap?

    Now for my own choke tube thread story. I have a Benelli that use chokes with threads that are clearly a square thread profile. long ago, I bought a new custom choke tube for the Benelli, and received a tube with V threads. The pitch was correct. Everything was correct except the thread form. Customer service at the Major Retailer neither understood nor cared about my complaint. "Just send it back for a refund."

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    A 44TPI 2 start sounds plausible to me. It'll make 44 TPI, but have a lead of 88 TPI.

    Pitch and Lead are different animals.

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    I think you have the right tap. Are you sure the tube is a thin wall tube?

  5. #5
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    Thank you to every one who replied. My understanding is that a 2 start tap lead is 2x the tpi. This is still confusing. However here is the update. I took a piece of an old barrel and followed the same procedure. The coke tube did not thread in, 1/4 turn and stopped. I checked that the choke was a thin wall and compatible. It was. Also I verified all of the tooling part numbers were correct. On the test barrel I tried recutting the threads. Luckily I found the original threads. I took the keeper off the bushing so that it would not come across the threads but drop through the barrel. I did this twice and the choke turned in. Repeated this process on the original barrel and it worked. I now have a fully functional shot gun with Tru-choke thin wall choke tubes that work great. Thanks again for the replies.


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