Question for Colt Canada arms tech

73582

73582

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I have read it and word on the street is when swaping barrels between IURs, MRRs and SAS uppers that it is not required to check head space.

Can any techs comment on the accuracy of this? Swaping an Danish IUR barrel into a MRR upper.

Your comments much appreciated.

Thanks
 
Properly?
How would you know if yours was made “properly”?
I know, by checking the head space!
Always a good idea to clean and check the headspace.
 
In general AR15 is designed such that head spacing gauging is NOT required. Headspace gauging is only used to see how much the weapon is worn for replacement. Hence, the use of the "Field gauge".

With the major manufacturer like Colt, FN, DD.... there isn't really a need.

If you have a barrel or/and a bolt of un-sure quality or manufacturer, this may give you a piece of mind. You do need to know the purposes of the 3 gauges - Go, No Go and Field. You need to have Go and No Go. In all these years, I only found one headspace problem in a factory rifle.

The money spent on these gauges are generally not worth it for one or two builds just for that piece of mind.
 
Thanks. I am aware these are like lego but as noted "properly" is the key word and was looking for a concensus on CC products.

2 out of 100 didnt spec sort of thing. The biz im in have housings that are suppose to be premachined and no shimming required. Very rarely one crops up out of spec when checking lash.
 
As a weapons tech I have run into many rifles made by colt Canada that failed headspace gauging. I'm not talking about the field reject gauge, just the standard no go. Do NOT confuse interchangeability with head space people. These are NOT the same thing. For example, a bolt that is considered to be interchangeable will not guarantee good headspace, as the chamber may be worn and will still fail gauging. The purpose of checking headspace with each barrel or bolt combination is to ensure that it is correct and therefore safe. Remember: headspace is the distance from the face of the bolt to the shoulders in the chamber were the cartridge seats. Even if the parts are considered to be interchangeable, these are just tolerances and many things can affect these; not limited to equipment wearing out at the factory, improper assembly, dirt, oil, carbon, third party parts replacements (cam pins, bolt heads, etc.)...

Always be certain that your rifle is in good condition. A ruptured cartridge is no joke. It can cause injury and damage your rifle.

If you're really in a pinch, you can always look for indications of excessive headspace on your cartridges after firing. Things like pushed out primers and stretching of the cartridge case can indicate possible excessive headspace and are a warning sign that a ruptured case may be to come.
 
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LouCoassin said:
As a weapons tech I have run into many rifles made by colt Canada that failed headspace gauging. I'm not talking about the field reject gauge, just the standard no go. Do NOT confuse interchangeability with head space people.
Click to expand...

Out of curiosity is this with 5.56 go/no-go or 223 go/no-go gauges? As I understand it, the 5.56 no-go is basically a 223 field, no?
 
5.56, but it doesn't matter. Its the same principle for both, but 223 is not 5.56. The cartridge has minor differences.

I'm not familiar with the exact differences between the no go 5.56 and the field reject for the 223. You would have to look up the specifications for each. After doing a little research, the headspace on 5.56 is longer by approx. 0.004" which isn't very significant. This info comes from Forester Products who make headspace gauges.

Headspace:
5.56 = 1.4736"
.223 = 1.4636"
.223 field = 1.4696"
 
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