Problem. M7 requires a 6.1mm drill.
1/4"=6.35mm!
1/4"=6.35mm!
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Blown nipple.
- Thread starter andy52
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The drill diameter is not a huge problem. A 6.1mm drill is 0.2402" in diameter. A 15/64" drill bit is 0.2344" in diameter and should provide a 75% thread fit when used for a 7mmX1mm tap. A 'B' letter size drill is 0.2380", and a 'C' letter size drill is 0.2420" in diameter, the first being slightly more than a 75% thread fit, and the second slightly less, but any of the three better than what you have now.
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Oh boy.....
Has not a 1/4" nipple blown out?
If so the current hole will be to big for a 7mm thread.
If I'm correct a helicoil kit will be needed or go to an 8mm threaded nipple.
Yup, my buddy got the gun reasonable enough so fixing it is still a good investment. When he first got it he showed me the peen marks and asked about them, I told him I had no idea why someone would do that guess I do now....
You cannot fix stupid, but you can numb it with a 2X4.
If the 1/4 -28 nipple is blowing out then that means the hole is already close to .250"
Woody Morgan
62 Cal.
OK guys it's fixed.....I think 
. I didn't re-drill the hole I just re-tapped it with the 7x1 tap and the existing hole. The threads came out nice and clean and a 7x1 nipple snugged up firm. Tomorrow I'll face off the breech plug to remove those ugly peens and post up some photos but the story won't be over until it's fired.
. I didn't re-drill the hole I just re-tapped it with the 7x1 tap and the existing hole. The threads came out nice and clean and a 7x1 nipple snugged up firm. Tomorrow I'll face off the breech plug to remove those ugly peens and post up some photos but the story won't be over until it's fired.
7mm=.275" -.250"=.025"
I think you may have very shallow threads!
I think you may have very shallow threads!
I'll post some photos but the threads look fully cut to me.
Can you tell me what the thread size is on a William Moore shotgun? I just recently did the same procedure on one due to rusted threads and it fired just fine, now granted it was loaded with a smaller charge than this rifle.
No idea friend.
Feltwad would be the one to ask.
Great community here. I’ve learned a lot on this one thread, and I hope I don’t ever have this experience.
It is a PITA, but sometimes you have to do what works. I didn't tell these guys that I broke the tap off in the hole when I was working on this and had to cryogenically freeze the piece in the hole and shatter it with a punch to get it out....
. It happens.user 51067
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The threaded breech-hole for the nipple was clearly cross-threaded and re-threaded with the improperly threaded nipple! "Drifting" the metal with a punch to tighten the hole is a "hack" move! An insert (time-sert, helicoil, etc) could be safely used. Even welding the hole shut and re-drilling and tapping would be better than what was attempted!
user 51067
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A hole like that would most certainly need a bottom tap, or (as you now know) you would break the tap off in the hole!It is a PITA, but sometimes you have to do what works. I didn't tell these guys that I broke the tap off in the hole when I was working on this and had to cryogenically freeze the piece in the hole and shatter it with a punch to get it out....
Yes, I was using a bottom tap, plenty of lube, and cleaned the chips regularly. All I blame it on is a cheaply made Chinese tap. The freeze method worked easily enough to get the piece out so all is well at this point.
user 51067
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I grind my own bottom taps from the regular taps that are no longer as useful. And no CHI-NA anything unless it is a tool to be destroyed in the process of whatever I am creating (ie: Harbor Freight). Too many "good thing" accidentally "die" as a result of "bad tools"-especially screwdrivers!
Here are the results before and after. I faced off the breech and removed as much of the peen marks as I could. The nipple treaded down firmly now I need to touch it up with some borwning and take it out and shoot.
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Griz44Mag
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Been there - done that. On an engine block - can be done - but it's a big PITA.It is a PITA, but sometimes you have to do what works. I didn't tell these guys that I broke the tap off in the hole when I was working on this and had to cryogenically freeze the piece in the hole and shatter it with a punch to get it out....
I had leakage from a helicoil - I used a solid SS one the last hole I had to re-thread.
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where there is will, there is a way! good work.
think i would have left the peen marks for decoration. but i do weird stuff to MY toys to make them mine,
think i would have left the peen marks for decoration. but i do weird stuff to MY toys to make them mine,
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