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EvolutionWeaponry
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Posted: 11/4/2010 5:01:27 PM EST
Yes you tighten and loosen 3 times. It helps seat the barrel nut so it doesnt work its way loose. Make sur you get ATLEAST 30lbs on the barrel nut, but overtightening can strip the theeth on the barrel nut or possibly fracture the upper receiver. However, I have put over 100lbs on a barrel nut before and with proper technique only slightly malformed the teeth on the barrel nut, no problems with it after the remainder of service life of barrel and bolt. That same carbine was carried in Afghan and tested far beyond normal field use by US soldier.
jdoming728
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Posted: 12/24/2010 3:24:52 PM EST
Most of us who have worked on cars or put anything together know the feeling between a tight bolt and a loose one... So that being said you really dont need a tourqe wrench just remember to the the nut tight and then look to see if you have to index it farther foward in order to install the gas tube... As a rule I never loosen the nut to get to the the proper alighnment always tighten... 99.9 percent of the time if your installing a new stick and carrier its not needed to check the headspace espically if your stick already came spaced and your not the one putting it together... But for saftey's sake you should have a Headspace guage set and a torque wrench.. I have build a dozen from new parts and never have found one out of spec....I always use Moss and Oly barrels and spikes carriers.....
BigDrink
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Posted: 3/9/2011 9:12:32 PM EST
Originally Posted By FALARAK:
Originally Posted By sniperfrog:
How critical is the 40 inch pounds for the receiver extension? Inch/pounds torque wrenches are pretty expensive. I installed a new Vltor stock tube and I snugged it up but it was probably more than 40 inch pounds. Is overtightening the buffer tube a bad thing?


Non-issue. That is not a critical torque spec. Just get it snug. Then - optionally stake it if you want to, or you can use *one drop* of *blue* loctite to optionaly add some insurance against it loosening up over time. I do neither. Just get it good and snug and I am sure I am well over 40 inch pounds.



37 to 40 INCH pounds has been determined as "Hand Tight". If you need to put a torque value on "Hand Tight" it is 37 to 40 INCH pounds. Apparently some have decided the carbine RE castle nut is supposed to be torqued to 40 FT lbs and people do it... and the RE's take it so Id say if you are a tad over 40 inch lbs you are fine Its obviously been proven the castle nut can be torqued from Zero to 40 FT LBS(480 INCH pounds). Commercial RE's I however would not torqued to 40 FT LBS going a tad over 40 FT LBS will break or warp a commercial tube.
Halschick
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Posted: 5/7/2011 6:57:35 PM EST
I recently had an experience with Century Arms that is worth sharing.

There was a recent posting about the Century Arms C-15 Sporter. This model rifle was my first AR purchase approximately 2 and ½ years ago. A bought it as a “shooter” and it lead to a severe case of BRD. You, who have been infected, know the scenario. A couple of SP1’s followed and then several builds from the recently available Colt Parts Kits and also a finished C-15A-1 from Century Arms.

Back to the C-15 Sporter. The quality of the rifle was good, especially for the price. It had mostly new components except for the Colt BCG and modified FCG. I first shot it about a year or so ago (40 rounds) and it functioned flawlessly.

Recently, I purchased a set of headspace gauges from Brownells and decided to check the headspace on the C-15. With a stripped bolt, it did not pass the “Go” gauge test. I almost crapped, since I had already shot the rifle and headspace is almost never an issue on properly assembled AR's. I called Century and they were very helpful. I eventually got to a Customer Service Rep. who told me that they only use “no-go” gauges when they check their rifles. He also said that “if it shot OK, what was I worried about?’ When I expressed my concern about the safety of the weapon, due to the faulty headspace, he offered to repair it at the factory, but, I would have to pay the shipping. At that point, I elected to use a local gunsmith. He verified that the headspace was, in fact, wrong. He also said that it appeared that the rifle chamber had not had the finish reaming. He fixed it for $60.00 and I am now “good to go”. I plan to go to the range this week.

I am concerned about the large number of these C-15 rifles and also the M16-A1 Kits and assembled C-15A-1’s that have recently come from Century and other suppliers with barrels “in the white” and also “parked”. Have their chambers been finish reamed or not? My advice is – Check the headspace on these rifles before you shoot them! I am not bashing Century Arms, I have bought their products for years, their Customer Service is excellent, and, as an FFL, I will continue to buy their products. I will, however, check the headspace where new barrels are concerned.

Hal

PS - The headspace on my C-15A-1 is fine.


jdoming728
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Posted: 5/7/2011 7:35:19 PM EST
To be safe I would but if your installing a New Bolt and carrier then no you really dont have to.... If its your gun but if your working on anothers gun Id check it for safteys sake.....New Parts usually dont have to be checked unless you doubt the manufacture you purchased it from then Its not a bad Idea.....
sinlessorrow
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Posted: 5/28/2011 11:23:04 AM EST
[Last Edit: 5/28/2011 1:11:14 PM EST by sinlessorrow]
I just took a spikes buffer tube off that was torqued to 38ft/lbs, after i got the castle nut off the buffer tube threads were tore up. It asnt going anywhere but it was also unusable after removal, there was little shard of aluminum all over my hands

I have mine at 40in/lbs still trying to decide if i should keep it there
6mmAR15
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Posted: 7/5/2011 10:58:19 AM EST
Originally Posted By FALARAK:
Originally Posted By AR15Texan:
Need some help with headspace. I finished building a 24" Varmint AR15. I bought the Forster .223REM GO and NOGO headspace gauges and checked the chamber tonight. The GO Gauge has 1.4636 and the NOGO has 1.4666. I could not close the bolt on either the GO or the NOGO gauge.

Below are the rifle's details:

DPMS lower with Rock River Arms LPK and two-stage trigger kit.
RRA A4 Stripped Upper with charging handle and foward assist
DPMS 24" Bull Barrel with Extension installed.
JP Enterprise free-float handguard
DPMS flat top gas block and gas tube
Mil-spec BCG
Magpul PRS stock with Rifle buffer tube, spring, and buffer

I separated the upper and lower receivers. I then removed the extractor and ejector. I placed the bolt back into the bolt carrier. Installed the key, firing pin, and retaining clip into the bolt carrier. I inserted the GO gauge and then slide the BCG into the upper. I pushed the BCG forward and saw that the bolt started to rotate about 10 degrees and stop. The NOGO gauge was about the same.

I then grabbed another BCG that has seen about 350-400 rounds. I only removed the extractor as I was having trouble getting the ejector roll pin out. I then installed this BCG assembly into the upper. I applied more pressure than before as I could feel the ejector spring compress. The bolt then snapped into battery. I then tried the NOGO and it too snap into battery with about the same pressure. I figured I was pushing too hard in order to overcome the ejector spring and concluded that this test was no good.

I then spent some more time on the used BCG and finally got the ejector roll pin out. I then tried it back in the DPMS 24" upper. This time the bolt closed on the GO gauge but it still took more pressure than I thought should be used. Shouldn't I see the bolt rotate easily on the GO gauge? Next I tried the NOGO gauge on the used BCG. The bolt started to rotate a few degrees but then stopped.

I then tried the brand new BCG on the older upper. This is a J&T kit upper with a 16" barrel. The new BCG would not close on the GO or NOGO gauge. So it looks like my chamber and bolt are too tight. Doesn't the GO gauge measure maximum SAMMI length. Should I not run any ammunition through the new AR? Should I try some other bolts?





Most NATO chambered AR's will close on a civilian NOGO. It does sounds like you are checking them correctly... but the fact you are tight on a civvy GO gauge in both weapons is highly suspect. Are you sure both chambers and bolts, and barrel extension are impeccably clean? What you are describing is extremely rare, and likely something else is happening. Have you tested using a live round? How much force is required to chamber that?


I just built a a carbine using a Colt 14.5 pencil barel..........the bolt will not close on a civi 223 no-0go gauge

Retro556
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Posted: 10/15/2011 3:13:42 AM EST
I have a 1981 era SP-1 with approx. 10,000 rounds down range that will not close on a 5.56 go Gage, no signs of over pressure.
ntwillea
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Posted: 11/26/2011 3:21:27 PM EST
[Last Edit: 11/26/2011 3:23:15 PM EST by ntwillea]
Quick couple of questions, I found Field, Go, No-Go and a set of MATCH, 5.56mm headspace gauges here:
Del-Ton Parts

Not sure which (if any) are within spec tho. According to DF's specs on a GO the gauge being offered is off by .0010?

As far as I can read off the match set these are PTG (Pacific Tool and Gauge).

1) Are these safe to use for proper military head spacing (all my barrels so far are mil spec)?

2) Anyone own these or other PTG gauges have any pros/cons that they feel would be helpful in helping me decide on avoiding/procuring them?

3) Is the match set for match barrels only? From the description the .330 is static, I'm guessing this is the shoulder angle and the 1.4xxx is to gauge wear in the bbl?


Thanks to all in advance.

EDIT-Fixed link
DR-B
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Posted: 6/30/2012 11:16:12 PM EST
Originally Posted By FALARAK:

Now - if we did push the barrel forward another .003" (for instance) this still has ZERO effect on headspace. The headspace is set from the bolt FACE to the chamber. This distance is set by a factor of the back of the bolt lugs, contacting the barrel exension lugs. This is why, ONLY the barrel extension, when installed to the barrel, controls the headspace. All bolts are made to the same spec. Therefore, the position of the barrel in the upper receiver makes no difference, because the bolt carrier is freely moving, and will just simply slide an extra .003" forward in this case. There is a large margin of tolerance here.

As an end user - you CANNOT have any impact to headspace. This is set by the barrel maker when they install the extension on the barrel and pin it. Nothing you do to the weapon can increase or decrease headspace. All you can do is *verify* headspace with a gauge, and replace the barrel if it is badly out of spec, which is extremely rare.


OK, I've been trying to wrap my brain around this head space issue and the comments above finally made it all start coming together. Now since I am a visual person, I sketched up what I think is a proper representation of head space. Please confirm.

https://lh5.googleusercontent.com/-WsGWLYCMMaQ/T-_NPy0G-9I/AAAAAAAAAdQ/yjwpxbfgRNQ/s912/Head%2520Space%25201.png
FALARAK
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Posted: 7/1/2012 8:49:40 PM EST
[Last Edit: 7/1/2012 8:49:50 PM EST by FALARAK]

Originally Posted By DR-B:
Originally Posted By FALARAK:

Now - if we did push the barrel forward another .003" (for instance) this still has ZERO effect on headspace. The headspace is set from the bolt FACE to the chamber. This distance is set by a factor of the back of the bolt lugs, contacting the barrel exension lugs. This is why, ONLY the barrel extension, when installed to the barrel, controls the headspace. All bolts are made to the same spec. Therefore, the position of the barrel in the upper receiver makes no difference, because the bolt carrier is freely moving, and will just simply slide an extra .003" forward in this case. There is a large margin of tolerance here.

As an end user - you CANNOT have any impact to headspace. This is set by the barrel maker when they install the extension on the barrel and pin it. Nothing you do to the weapon can increase or decrease headspace. All you can do is *verify* headspace with a gauge, and replace the barrel if it is badly out of spec, which is extremely rare.


OK, I've been trying to wrap my brain around this head space issue and the comments above finally made it all start coming together. Now since I am a visual person, I sketched up what I think is a proper representation of head space. Please confirm.

https://lh5.googleusercontent.com/-WsGWLYCMMaQ/T-_NPy0G-9I/AAAAAAAAAdQ/yjwpxbfgRNQ/s912/Head%2520Space%25201.png


It is a rough drawing - but correct in that it shows the back of the bolt lugs against the barrel extension lugs, and the bolt face setting the headspace to the barrel chamber.

Sorry about the mayonnaise, guys.
DR-B
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Posted: 7/1/2012 9:21:57 PM EST
Originally Posted By FALARAK:

It is a rough drawing - but correct in that it shows the back of the bolt lugs against the barrel extension lugs, and the bolt face setting the headspace to the barrel chamber.



Thanks for the confirmation FALARAK. I know it is a crude drawing, I just wanted to represent it with a picture to ensure I'm on the right track in my understanding. This leads me to a couple more questions. Understand that I am asking for academic purposes, not to justify my current build.

So, based on my sketch, which part will likely wear over time? I assume that it will be the forward face of the barrel extension lugs and/or the aft face of the bolt lugs. Also, when this wear happens, what actual condition will create an unsafe condition? Too much gap?

Thanks again.
FALARAK
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Posted: 7/2/2012 11:10:40 AM EST

Originally Posted By DR-B:

So, based on my sketch, which part will likely wear over time? I assume that it will be the forward face of the barrel extension lugs and/or the aft face of the bolt lugs. Also, when this wear happens, what actual condition will create an unsafe condition? Too much gap?



Wear over time will be:

1. Barrel extension lug face.
2. Rear lugs on bolt.

There will be limited wear on the bolt face from erosion, and front face bolt lugs from slamming into the barrel, but this wont affect headspace.

The wear over time will not create an unsafe condition. It could potentialy wear enough over time to close on a no-go or even field or field II gauge. However, this does not create an unsafe condition, as this amount of extended headspace is still far less than the headspace set on machineguns that fire the same cartridge, such as the M249. It will have a slightly diminished accuracy potential and will allow more stretching of brass. That said - the wear induced on the barrel extension is very minor given the barrel's serviceable life of around 10,000 rounds. There just isnt enough time in a barrels service life to worry with headspace from wear. However, it would be feasible to continue replacing a barrel every 10,000 rounds, using the same bolt, and see enough wear on the bolt to induce extended headspace. Generally when replacing the barrel, it is a good idea to replace the bolt with a fresh, in spec bolt. However, I have worn out barrels, and continued to use the same bolt with no cause for concern.

Again - repeating information already in this thread, too LITTLE headspace poses much more of a dangerous situation (pressure spike), than excessive headspace. (assuming the excessive headspace is not extreme, such as an improperly built barrel.)
Sorry about the mayonnaise, guys.
fridge72
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Posted: 10/31/2012 8:12:12 PM EST
For those who are more visual I found this link to be helpful also somewhere that had said gauges in stock. $30 each
dtuns77
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Posted: 11/9/2012 10:52:47 PM EST
What gauge do I use for a wylde chamber .556 or .223 REM?
SubgunFun
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Posted: 12/19/2012 4:06:39 PM EST
Ok, I ordered the NO GO gauge from Brownells and my bolt won't close on it. WoooHoo! I am glad to have that verification.
One note... I dismantled my bolt to do this, but put it in the carrier... no firing pin and no firing pin retaining pin, but the cam pin was in to hold the bolt in and allow it to turn. Well, the cam pin must have turned a tad while the bolt was closed. Wow... I had very little movement in the carrier but moved it back and forth many many times and finally the cam must have rotated back in position and I was able to get the bolt/carrier out.
So, my suggestion, remove the extractor and ejector plunger/spring, but still put your bolt carrier group together with the bolt, firing pin and FP retaining pin.
Other than that, the suggestions on this thread were excellent and now I am not worried about firing my new upper for the first time!
Thanks guys!
-SubgunFun

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RV4driver
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Posted: 12/25/2012 8:51:14 PM EST
Just a short item from my first build. I'm familiar with torque wrenches, the last thing I built was an airplane. Torque was your GOD.
IF you're not using a torque wrench, but the AR multi-tool, be aware that the ft-lb wrench is about twice as long as the multi-tool, so since the long torque wrench needed quite a bit of effort to achieve the proper max torque for the barrel nut, I would assume that just the short multi-tool would need A BUNCH of effort.

Next, don't underestimate the helpful effect of some moly grease. Without it, I couldn't achieve any more than the minimum torque. All aircraft torque values are rated as dry, and lubed. After the moly, torque THREE times, loosening each time between, the max torque was easy to achieve. So, NO short cuts.
Sure, do it without a torque wrench, but be aware of the short arm of the multi-tool, and give it some serious muscle. And be sure to use moly grease and loosen twice, torqueing it up on the last effort. Remember, the range is something like 40 to 80 inch-lbs, so it's quite broad.
Glockknocker
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Posted: 12/29/2012 10:27:49 PM EST
[Last Edit: 12/29/2012 10:33:28 PM EST by Glockknocker]
I just put a YHM free float on mine. I haven't shot it yet but does anyone think I should check the headspace before I shoot it? I noticed that I over torqued it probably by one of the gas tube holes on the jam nut since I have just a paper thin sized gap between the upper and free float rail extension. Everybody's got me all second guessing myself and wondering if I shoulda got the damn gages when I ordered everything. I looked on brownells and midway, and couldn't find a field gage in 5.56 or .223. I got a 5.56 so I figured I'd get that one if I choose to make the buy. I know ultimately its better safe than sorry, but does anyone think I need to buy the gages? Also the barrel and receiver are still the same before I did the free flair upgrade if that also makes any difference.
FALARAK
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Posted: 12/30/2012 11:38:08 AM EST
[Last Edit: 2/1/2013 10:49:08 AM EST by FALARAK]
Originally Posted By Glockknocker:
I just put a YHM free float on mine. I haven't shot it yet but does anyone think I should check the headspace before I shoot it? I noticed that I over torqued it probably by one of the gas tube holes on the jam nut since I have just a paper thin sized gap between the upper and free float rail extension. Everybody's got me all second guessing myself and wondering if I shoulda got the damn gages when I ordered everything. I looked on brownells and midway, and couldn't find a field gage in 5.56 or .223. I got a 5.56 so I figured I'd get that one if I choose to make the buy. I know ultimately its better safe than sorry, but does anyone think I need to buy the gages? Also the barrel and receiver are still the same before I did the free flair upgrade if that also makes any difference.


No. As stated many times in this thread, if you aren't changing the barrel extension, or the bolt, you CANNOT affect headspace in any way. Too many others have posted in this thread with silly or bad information. In general, there is no need to check headspace on ANY AR15 unless you are the barrel maker, or reaming the chamber and installing the barrel extension, which is the job of the barrel manufacturer or final barrel smith. By assembling or reconfiguring, you cannot affect headspace, and that has been covered already in this thread.
Sorry about the mayonnaise, guys.
rangem4
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Posted: 2/18/2013 10:27:30 AM EST
I bought a JP Enterprises 16" stainless super match barrel kit. 1:8 twist and it came with a match grade bolt.
Considering what I have read in this forum I am curious why they supply the bolt.
I am very impressed with the product. It is flat black with a highly polished feed ramp and the bolt is a thing of beauty.
The Bennie Cooley seamless compensator is awesome.
Suburban
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Posted: 2/19/2013 10:44:50 PM EST
Originally Posted By rangem4:
I bought a JP Enterprises 16" stainless super match barrel kit. 1:8 twist and it came with a match grade bolt.
Considering what I have read in this forum I am curious why they supply the bolt.
I am very impressed with the product. It is flat black with a highly polished feed ramp and the bolt is a thing of beauty.
The Bennie Cooley seamless compensator is awesome.


It's not terribly unusual, particularly with match barrels. JP may want to precisely set the headspace. The JP bolts are supposed to be made of a better steel, and last longer, but I'm not sure that "match grade bolt" is a real thing though.

http://www.majorpandemic.com/2012/01/jp-enterprise-ar15-barrel-kit-review.html
VA-gunnut
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Posted: 2/28/2013 6:25:22 PM EST
Bump for cleanup
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