Use of NS bolts with two gas holes

[RBruce]

When was the nickle steel bolt with two gas relief holes first used? TIA

Information

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[bb1]

If you are asking about the nickle steel, the change was made at #1,275,767. If you are asking about the holes, I can't help.

[John Beard]

When was the nickle steel bolt with two gas relief holes first used? TIA

Very early 1937.

Happy Holidays!

J.B.

[RBruce]

Thank you bb1 and John.