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Discussion Starter · #1 ·
I just had a quick question about headspacing, and I can't see anything quite like my question in the archive. I've got a virgin barrel (with no sight block or gas block or anything already attached) pressed into my front trunnion and the bolt closes on the go gauge, and won't close on no-go. However, when the bolt closes on the go gauge, it doesn't close super smoothly unless I tilt the carrier a little. But it does close. Is this something I should worry about? :dunno:

I don't want to spend the next hour trying to press the sucker in and out and risk screwing up the diameter of the chamber, but if this is a catastrophe waiting to happen I don't have a choice.
 

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I would not worry about it, the main thing is to get the go to fit and the no go not. You are there. A virgin barrel will not install smooth so to fine tune it further will be tricky and potential for screwups is high.
 

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I'd think that you would want it to close a little tightly on a go gauge because the headspace will open up a little over time. My AR10 build closes pretty tightly on a go but won't even bugde on the no-go. It's a Fulton BCG and barrel. I spoke to them and they said that this was by design for the reason stated above.
 

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Try it with a cartridge (safely) and with just the bolt., no carrier and see how it reacts. Just a few different avenues to doube check. Sounds like you are OK., but do it once and do it right is always a good idea.
 

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First check it an set the barrel with out the carrier . If aftr you install the carrier the bolt does then not close you have a mechanical problem not a head space issue .

Tilting carriers is not part of setting head space .

If you have uneven lug engagemt then a carrier will give you a false head space check.

head space is the longest distance from the bolt face to the back of the guage PERIOD . If that distance is made by tilting the bolt then you have a mechanical problem .

I head space with no carrier look to see if the bolts shaft loos true tot he bore . i then install the carrier an recheck if it dosent close i fix the problem . I dont drill the pin hole untill It works correct with an with out the carrier ,


It's a Fulton BCG and barrel. I spoke to them and they said that this was by design for the reason stated above. what the hell does that mean ??

did fulton make the bolt control group ? bolt , carrier , barrel trunion ? do there barrels press hard by design ?? what design feature makes it hard to press a barrel or need to cock a bolt to get it to rotate in ????????????????

I proper barrel should have about .001" interferance fit an should press in pretty smoth if the bore is lubricated an the edge of the barrrel pin bore is champhered properly .

You need to set the head space properly If it takes all day so be it .
 

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First check it an set the barrel with out the carrier . If aftr you install the carrier the bolt does then not close you have a mechanical problem not a head space issue .

Tilting carriers is not part of setting head space .

If you have uneven lug engagemt then a carrier will give you a false head space check.

head space is the longest distance from the bolt face to the back of the guage PERIOD . If that distance is made by tilting the bolt then you have a mechanical problem .

I head space with no carrier look to see if the bolts shaft loos true tot he bore . i then install the carrier an recheck if it dosent close i fix the problem . I dont drill the pin hole untill It works correct with an with out the carrier ,


It's a Fulton BCG and barrel. I spoke to them and they said that this was by design for the reason stated above. what the hell does that mean ??

did fulton make the bolt control group ? bolt , carrier , barrel trunion ? do there barrels press hard by design ?? what design feature makes it hard to press a barrel or need to cock a bolt to get it to rotate in ????????????????

I proper barrel should have about .001" interferance fit an should press in pretty smoth if the bore is lubricated an the edge of the barrrel pin bore is champhered properly .

You need to set the head space properly If it takes all day so be it .
 

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when im head spacing i take the bolt out of the carrierer with the go gauge and try and rotate it by hand , with the "no go" i put it in the carrierer and try and force it closed. never had any issues doing it this way.
 

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Discussion Starter · #10 ·
Thanks for the replies. I decided that the headspace was probably bad so I attempted to to fix it. Got it right on the first refit. :happy: now I'm not scared to field test it when the time comes.

As a side note, but somewhat related, when you guys mate barrel components to a virgin barrel what's the step by step you use? Seemed to me the best idea was to get the hs the way I wanted it, install the barrel pin and then pressing on everything. If I didn't do the pin I think it would shifted as I pressed the rsb, correct?
 

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Discussion Starter · #11 ·
Thanks for the replies. I decided that the headspace was probably bad so I attempted to to fix it. Got it right on the first refit. :happy: now I'm not scared to field test it when the time comes.

As a side note, but somewhat related, when you guys mate barrel components to a virgin barrel what's the step by step you use? Seemed to me the best idea was to get the hs the way I wanted it, install the barrel pin and then pressing on everything. If I didn't do the pin I think it would shifted as I pressed the rsb, correct?
 

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you might move the barrel if your installing componets if the barrel is not pinned correct.

If the barrel has a gas port drilled I like to assmble the componets first bu t leave them un pinned . I leave the GB pressed back a little . I install the BG over the port an use this to align the barrel when installing it inthe trunion . I leave every thing back from its final position by a little an once I have it head spaced an pinned an all the stuff is aligned an not canted I then press the RSB back to were the Dust cover fits correct., then move the GB were the gas tube fits correct an still over the port . when its all right an looks good drill the pin holes .

on a barrel that has no gas port I just press in the barrel were the extractor cut is correct an set head space . I doubel check the bot an extractor does not hit or other issues I pin the barrel I then install the rest of the components I drill the port last .

SO WHAT IS WITH A FULTON BCG????????????????????????????????????//
 

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you might move the barrel if your installing componets if the barrel is not pinned correct.

If the barrel has a gas port drilled I like to assmble the componets first bu t leave them un pinned . I leave the GB pressed back a little . I install the BG over the port an use this to align the barrel when installing it inthe trunion . I leave every thing back from its final position by a little an once I have it head spaced an pinned an all the stuff is aligned an not canted I then press the RSB back to were the Dust cover fits correct., then move the GB were the gas tube fits correct an still over the port . when its all right an looks good drill the pin holes .

on a barrel that has no gas port I just press in the barrel were the extractor cut is correct an set head space . I doubel check the bot an extractor does not hit or other issues I pin the barrel I then install the rest of the components I drill the port last .

SO WHAT IS WITH A FULTON BCG????????????????????????????????????//
 

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Hey guys instead of starting a new topic I figure Id ask in here.

Working on my headspacing, NO-GO gauge and the bolt only turns about half of its full rotation. GO gauge closes all but a sheet of papers width. I can see a tiny bit of light between the top tab(for lack of a better word) on the bolt and the trunnion. I also tested with 20 random rounds, closes completely and smoothly with every one of them.

If I understand correctly from reading the Accurizing the AK thread, the tighter it closes with the correct headspace=more accuracy. Dont have a problem backing it out a bit again but if I accidently came upon "perfection" I dont want to mess with it :)

Thanks in advance, I've still got some things to do on the receiver while I wait for your advice.


EDIT: Nevermind guys I tapped the barrel out a hair more and the GO completely closes now. Thanks Sprat(I think?)I for mentioning the pulley puller in the other thread, worked very well with a stack of pennys on top of the chamber opening.
 

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Thanks for the replies. I decided that the headspace was probably bad so I attempted to to fix it. Got it right on the first refit. :happy: now I'm not scared to field test it when the time comes.

As a side note, but somewhat related, when you guys mate barrel components to a virgin barrel what's the step by step you use? Seemed to me the best idea was to get the hs the way I wanted it, install the barrel pin and then pressing on everything. If I didn't do the pin I think it would shifted as I pressed the rsb, correct?
It depends on the barrel type/configuration. If it is a predilled gas port and/or HGR retainer slots it is often easier to populate but not pin the components so you can "clock" the barrel to be vertical alignment. Then drill the barrel pin channel.
If undrilled gas port then the extractior clearance is the main clocking. Drill channel & pin and then "stack" components rear to front and mock up with receiver cover, gas tube etc, as you proceed.
 
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