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Just wondered if anyone could steer me in the right direction, I bought a new rifle and had it threaded by a reputable riflesmith down south before having it sent up here. I requested 18x1 to fit my ATEC Maxim which I also use on another rifle. 

Unfortunately my mod will only go on one turn and stop. I'm not going to try and force it for obvious reasons. But rather than go to the expense and hassle of sending it back down the road I wondered if its acceptable to try and get hold of an 18x1 split die and make it fit that way. 

It was suggested to me to try fine valve grinding paste mixed with a little oil and thread it on half a turn a time and back it off but am reluctant to go there as my ATEC fits my other rifle fine.

And to clarify it is 18x1 my threaded cap from the other rifle fits on ok, albeit a hair tighter.

Advice or opinions would be great. Thank you. 

I would try the split die it depends how he cut the thread if he cut it on the lathe he may not of cut it deep enough.

I would expect the thread to be machine cut and checked with a thread ring gauge to confirm it was correct however you could carefully run a split die down it as a last resort. Take your time use a good quality die and use lots of lubricant.

ovenpaa wrote:I would expect the thread to be machine cut and checked with a thread ring gauge to confirm it was correct however you could carefully run a split die down it as a last resort. Take your time use a good quality die and use lots of lubricant.

What constitutes a good quality die? I'll need to buy one so any info would be appreciated.

Also why a last resort? You have me nervous now! Is it bad practice? Lots to go wrong? Measuring across the threads between my other 18x1 thread and this one there is a difference of about 6 thou.

RFD'ing it back down the road and back will cost me the best part of £100 plus any extra gunsmith charges so was keen to rectify it myself if I could. Thanks for the help so far folks.

farmer7 wrote: RFD'ing it back down the road and back will cost me the best part of £100 plus any extra gunsmith charges so was keen to rectify it myself if I could. Thanks for the help so far folks.

Have you spoken to the guy who did it?
Will he stand the cost, being as how he did the work?

ozone

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Are you sure he has cut the thread right. I would get in touch with him and have a word before you mess with the thread. Dies are like everything else there are cheap ones and more expensive ones I buy my taps and dies from Cromwell tools. (We have dozens of different sizes of taps and dies at work) Tracy tools do cheaper versions. But I would not do anything until you have spoken the the guy who did the work.

I just reread your original post a new rifle. You must be gutted.

I had a problem with the thread on my AKM where the muzzle brake was very tight and sorted it with a metric thread file a little at a time and it worked perfectly.

Yes but he has paid good money to a supposedly gun smith to have the work done professionally. It should be right he should not have to fettle it him self. If he messes with it him self the guy who done the original work will use that as a excuse not to fix it. Contact the guy you bought it from and have him sort it out. Any shipping back to him should be on his tab.

you are sure that the other rifle / cap / suppressor is actually m18x1?

if the cap fits on, it should be close enough to get it to fit. but as someone else mentioned, it may not be cut quite high enough.

i'd suggest you contact the 'smith, and probably suggest to them that it might be cheaper if they just buy you a HSS die for you to clean it up with, as £35 would be cheaper than return post each way.

if they have done it with a die themselves, it might be they have not done it deep enough and it only needs a tickle up.

how common is m18x1 in suppressors etc? are they likely to have had something machine cut to try on it?

A m18x1 thread is a very common thread any competent gunsmith should be very familiar with cutting this thread.
He should also have go and no go gauges if he is doing this on a regular basis.
(Perhaps its time I went into the gunsmithing business. )
http://www.gaugestools.com/m18x1-thread ... lug-gauge/