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Re: anyone built an AR platform rifle
Posted: Tue Mar 17, 2015 8:53 am
by teul2
How would you even get a gauge in there to check the head space? The bolt face is in front of the locking lugs, so when the bolt is closed, it it sealed in the locking "cavity".
Re: anyone built an AR platform rifle
Posted: Wed Mar 18, 2015 5:34 am
by Wildfowler
I've never used them but they look like a cartridge. They come as a set and you put them in the chamber. The bolt should close or not close indicate a problem depending on the gauge.
http://www.brownells.com/gunsmith-tools ... 26876.aspx
Re: anyone built an AR platform rifle
Posted: Thu Mar 19, 2015 9:23 am
by MudHog
Information on barrel changes and go/nogo gauges:
http://www.shootingtimes.com/reloading/ ... n-minutes/
This is on a Savage bolt action rifle, but similar on other sporting rifles that have a threaded barrel. Rebarreling isn't necessarily a gunsmith required task, IF the barrel is threaded.
I'm not aware that gauges are specific to reamers. The barrel, although reamed, should still meet SAAMI specs, which is what the gauges are built to.
Re: anyone built an AR platform rifle
Posted: Thu Mar 19, 2015 5:19 pm
by Wildfowler
Should have specified that I was referring to the fact that there is a difference between 5.56 and 223 Remington. Also 308 Winchester and 7.62 x 51 even though many people consider these 22 or 30 caliber chambers interchangeable. Are slight differences in the reamer dimensions which could cause errors.
Sorry for any confusion.
Re: anyone built an AR platform rifle
Posted: Fri Mar 20, 2015 8:46 am
by Wildfowler
Okay I've got to be honest, I may not know what I'm talking about?
They sell various gauges for 223 Remington, 223 wylde, and 556. I assumed there was a difference in those various chambers.
As best I can tell after looking into this a little further the only real difference in those chambers is in the throat portion which is in front of the shoulder and I don't understand how it could be possible for the gauge to detect differences in the throat portion of the various chambers?
So now I am totally confused as to why they sell the various chamber gauges?
Re: anyone built an AR platform rifle
Posted: Fri Mar 20, 2015 9:18 am
by teul2
Wildfowler wrote:Okay I've got to be honest, I may not know what I'm talking about?
They sell various gauges for 223 Remington, 223 wylde, and 556. I assumed there was a difference in those various chambers.
As best I can tell after looking into this a little further the only real difference in those chambers is in the throat portion which is in front of the shoulder and I don't understand how it could be possible for the gauge to detect differences in the throat portion of the various chambers?
So now I am totally confused as to why they sell the various chamber gauges?
http://en.wikipedia.org/wiki/5.56%C3%97 ... _Remington
Re: anyone built an AR platform rifle
Posted: Fri Mar 20, 2015 9:53 am
by kb7722
Wildfowler wrote:MudHog wrote:
If you intend to do the upper from scratch, you will need a NO GO gauge to set the head spacing.
I've always thought the headspace "is what it is" when the barrel had its chamber reamed by the gunsmith.
How do you "set" the headspace?
I've only assembled two uppers from scratch without having any gauges so In certainly no expert.
Thanks
Yes it "is what it is" but you have to make sure that its within tolerance using the gauge. This is important since you are probably buying all the components from different suppliers. So if one is slightly out or the machining tolerance for all components were to high side or all to the low side. You may have an issue. Do some google searches. There is alot of discussion on this out there. AR15 forum is a good source.