Ken Rummer
40 Cal.
- Joined
- Jun 5, 2008
- Messages
- 266
- Reaction score
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I bought a GM 54, 1"x32, 1:70 replacement barrel for my Renegade from Log Cabin Shop, Lodi, OH.
During cleanup following my first range session I discovered the nipple was M6x.75 thread instead of the expected 1/4-28..
The Log Cabin Shop owner checked his stock and found several more with metric nipples. He called Green Mountain and they requested the barrels be returned. This is currently being done.
It is too early to tell what the scope of this situation will be.
Screwing a metric nipple into an English thd hole will go without a lot of extra torgue, will damage both threads and obviously will not be a strong as designed. Only GM engineers can assess the risk and I think this will be a problem for them.
The m6x.75 nipple has a .236 dia thread and has 33.8 threads per inch (my calculation) You can check this without a metric thread gage by using a 32 tpi gage. This is close enough that 3 or 4 threads will fit the gage but not the entire length of the nipple thread.
During cleanup following my first range session I discovered the nipple was M6x.75 thread instead of the expected 1/4-28..
The Log Cabin Shop owner checked his stock and found several more with metric nipples. He called Green Mountain and they requested the barrels be returned. This is currently being done.
It is too early to tell what the scope of this situation will be.
Screwing a metric nipple into an English thd hole will go without a lot of extra torgue, will damage both threads and obviously will not be a strong as designed. Only GM engineers can assess the risk and I think this will be a problem for them.
The m6x.75 nipple has a .236 dia thread and has 33.8 threads per inch (my calculation) You can check this without a metric thread gage by using a 32 tpi gage. This is close enough that 3 or 4 threads will fit the gage but not the entire length of the nipple thread.