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Posted: 2/4/2010 2:15:19 AM EDT
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Well I finished my rifle for the most part last week and just now
got around to messing with it today. I decided to check to see how she cycled. Seemed okay, but I noticed that when she ejected a round, the primer had a mark on it from when the bolt was slamming it into battery. I cycled a few more through and they all had the same thing. I decided to check the headspacing, the NO-GO gauge passed fine as the bolt would not lock Down. But, when I put the GO gauge in, it wouldn't seat without alot of pressure either. Now I did pull an oh shit and and when I went to eject the gauge accidenly let it slam home  .
It did take a bit of force to eject it again but I got it out and inspected the chamber with a borescope and found no damage. I pulled upper off and tryed cycling some cases by hand and they seemed hard to lock into battery aswell, they also would still have a firing pin mark on the primer  the GO gauge takes a bit of pressure to engage into battery by hand aswell. Do I need to take this thing in and have it reamed or what? As I have never seen this before.
Here are the specs. Noveske 16.1 recon SS Denny's guns super m16 bcg VLTOR MUR-1A RRA Lower with 2 Stage trigger Smith Vortex FH YHM specter length FF Harris BiPod OD Miad OD UBR OD Rail covers |
| A firing pin mark on the primer is standard. All of my ARs have always marked the primer when feeding a round. That is why it is recommended to use harder primers when loading for a rifle with a floating firing pin (like the AR). It is probably a good idea to not chamber the same round repeatedly, just to err on the side of safety. |
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A firing pin mark on the primer is standard. All of my ARs have always marked the primer when feeding a round. That is why it is recommended to use harder primers when loading for a rifle with a floating firing pin (like the AR). It is probably a good idea to not chamber the same round repeatedly, just to err on the side of safety. Ditto what he said! There is no firing pin spring in the AR, so it should leave a small mark on the primer. It sounds like your upper is fine! 
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Primer marks are normal...
If you don't remove the extractor and the ejector, it will cause the feeling you describe while trying to close the bolt. It takes force to get the extractor to snap over the rim of either a cartridge or a gauge and the ejector is also spring loaded which adds more pressure. I would strip the bolt of the extractor and ejector then retry, you might get better results. Pasted from the build it yourself section of the AR-15 Forum... 
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Headspace: There is some dispute over the need to check the headspace on AR15/M16 rifles on these forums. Some say you must. Some say you should. Some say you don't have to. Whether you check the headspace on your rifle is up to you. The following is provided for your information… First, try this URL for an explanation of Headspacing: www.hybrid.ualr.edu/satu/headspace.html Then try this one for more enlightenment: www.fulton-armory.com/headspace.htm The Forster/SAAMI gauges available from Brownells are primarily intended for use with .223 Remington civilian rifles, but can be used with your AR15. The M16/AR15 series use their own peculiar specs for headspace, making it necessary to ignore the "Go' and "No-Go" markings, and look instead at the measurement marked on the gauge. The current military specifications for the M16 series call for headspace of not less than 1.4646” and not more than 1.4706” on a new rifle. The commercial Forster/SAAMI gauges are marked in 1,000ths of an inch instead the 10,000ths of an inch that the dedicated M16 gauges are. When installing a new barrel, the commercial gauge measuring 1.465" can be used in place of the M16 "Go" gauge. Consider the 4/10,000ths of an inch difference an extra margin of safety. The commercial 1.470" gauge (the commercial "Field" gauge) can be used to confirm that the headspace is within spec for a new rifle. Unfortunately, there are no gauges available to measure between 1.470" and 1.4730", the latter being the measurement on the M16 "Field" gauge. The M16 Field Service gauge measures a dimension of greater than 1.4730”. A rifle with a bolt that does not close on a Field Service gauge is considered safe to fire by the army, but not the Marines who use the military "No-Go" gauge for that measurement. Without using military Go or No-Go gauges, or commercial gauges marked with their measurements, you cannot know whether or not it is truly in spec. An interesting tidbit of information is that the Colt M16/AR15 Field gauge measures a dimension in excess of 1.4736”. It seems that the military has built in a bit more of a safety factor with their gauge. You should remove the extractor parts and the ejector, which normally requires four hands. Removing the ejector is a two-handed job if you have the proper tools, specifically a Sinclair Bolt Vice for the AR15. You can’t really reset the headspace on an AR15 with a chrome-lined chamber. That is set when the barrel extension is installed on the barrel. If you have an unlined barrel, with short headspace, a gunsmith can adjust it by cutting the chamber deeper with the appropriate chambering reamers. If the headspace is long, or the chamber chrome-lined, the only option is to try a different bolt until headspace checks good, or you run out of bolts. Then it is time for a new barrel. To recap, the specs are as follows:
New Rifle Headspace: 1.4646" to 1.4706" SAMMI headspace gauges to use: 1.465" and 1.470" Unsafe Rifle Headspace: 1.4736" Use the Colt M16/AR15 Field Gauge: 1.4736" or, The US military gauge: 1.4730” Note: The Forster/SAAMI "No-Go" gauge measures 1.467" Sources for Gauges - Brownells: www.Brownells.com SAAMI gauges and a whole lot of new AR15 parts and accessories. Sarco: www.sarcoinc.com Military “Field” gauge as well as other maintenance items and M16/AR15 parts and accessories. Quoted: Using the 1.4730 GI Field gauge, the carrier stops WAY short of the normal, in battery position - about 1/8" short. When I was checking HS on my ARs, I was REALLY perplexed by the tail end of the carrier sticking out WAY past the end of the upper. I'm thinking "wtf? how could this gauge have any meaning whatsoever if it's 1/8" (.125!) over what's "in battery" for this rifle??? I was initially stumped!
After digging through old posts from the AR15-list, I found that this is due to the last part of the carrier travel being dedicated to bolt rotation, thus the bolt will not move much further back into the carrier (bad way to word that - we know it's the carrier moving over the bolt, not the bolt moving into the carrier). In those old posts I also found that I wasn't the only person confused by this issue. Torque Values:
Compensator (Flash Suppressor) - 15 to 20 Ft. Lbs. Barrel Nut - 30 Ft. lbs. Minimum, not to exceed 80 Ft. Lbs. to align the next slot in the barrel nut. Carrier Key Screws - 35 INCH pounds to 40 INCH pounds. Lower Receiver Extension (Buffer Tube) Rifle - 35 to 39 Ft. Lbs. Carbine - Tighten the locking nut to 40 INCH pounds plus or minus 2 INCH pounds. The following link is a view of barrel break-in and cleaning from Krieger Barrels and Gale McMillan on a discussion forum:
From the Krieger Barrels web site: www.kriegerbarrels.com/RapidCat/catalog/pagetemplate.cfm?template=/RapidCat/common/viewPage.cfm&PageId=2558&CompanyId=1246 From Gale McMillan, courtesy AR15Fan: yarchive.net/gun/barrel/break_in.html All information in this thread was originally posted by Dave G, unless otherwise stated. |
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I decided to check the headspacing, the NO-GO gauge passed fine as the bolt would not lock Down. But, when I put the GO gauge in, it wouldn't seat without alot of pressure either. Now I did pull an oh shit and and when I went to eject the gauge accidenly let it slam home .
It did take a bit of force to eject it again ... This is the reason most are hesitant to loan out their GO NO-GO gauges. I'm certain you know that you don't eject gauges. You just don't care whether you damage them and put them out of spec. |
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I decided to check to see how she cycled. Seemed okay, but I noticed that when she ejected a round, the primer had a mark on it from when the bolt was slamming it into battery. I cycled a few more through and they all had the same thing. I decided to check the headspacing, the NO-GO gauge passed fine as the bolt would not lock Down. But, when I put the GO gauge in, it wouldn't seat without alot of pressure either. Now I did pull an oh shit and and when I went to eject the gauge accidenly let it slam home .
Noveske 16.1 recon SS Did you remove the ejector and extractor from the bolt first? |
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No, I did not remove the ejector, my gauges have the cut out for the ejector. I took into account the pressure it took for the extractor. It still felt like it took more pressure than it should to lockup. As for removing the extractor, I don't have a bolt vise.
And Richard, by it took a bit of force, it was no more than what is required to engage a round on a removed upper by hand, which is more than I think it should be. Also, It's my equipment, if I want to use the ejector to extract my gauge, then grab it from the bolt I will. It's not like I ment for it to slam home the first time, and it's not like I ejected the thing accross the room. As for everyone else, thanks for the input, I will check the firing pin strike on the 6 other rifles in the house, I don't recall this but maybe I never looked hard enough. |
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A firing pin mark on the primer is standard. . This, and it IS covered in the tacked thread marked READ FIRST. Alright, well just delete the thread then. My fault for missing that. But it wasn't my only question, as every other ar I can let the bolt slide closed slowly and it will chamber just fine, on this one, it takes a bit more than that. |
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As for removing the extractor, I don't have a bolt vise. No "bolt vise" is needed to remove the extractor. Not being a #$% but you should be at least that familiar with your weapon if you built it...?? 
I am familiar with it, I know a vise is not required, even "guide" said it's a 4 handed job, last time I checked I only had 2, it also suggests a bolt vise. |
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As for removing the extractor, I don't have a bolt vise. No "bolt vise" is needed to remove the extractor. Not being a #$% but you should be at least that familiar with your weapon if you built it...??
I am familiar with it, I know a vise is not required, even "guide" said it's a 4 handed job, last time I checked I only had 2, it also suggests a bolt vise. That's the EJECTOR not the Extractor. Extractor removal is a part of field stripping. |
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Here is a thread covering this very question and Bill Alexander explained in detail: http://www.m4carbine.net/showthread.php?t=28296&highlight=headspace%2A Thank you, that was the most helpfull post, I should have looked there, at least people are not dicks about someone asking a question over there. |
I answered all of your question in the first response. If you think people are being dicks it's because you are over thinking your gun. Have you shot the gun? Does it function? Often people monkey with their guns and fuck them up before they even shoot them to see if they work Quoted: Quoted: Here is a thread covering this very question and Bill Alexander explained in detail: http://www.m4carbine.net/showthread.php?t=28296&highlight=headspace%2A Thank you, that was the most helpfull post, I should have looked there, at least people are not dicks about someone asking a question over there. |
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I answered all of your question in the first response. If you think people are being dicks it's because you are over thinking your gun. Have you shot the gun? Does it function? Often people monkey with their guns and fuck them up before they even shoot them to see if they work
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Here is a thread covering this very question and Bill Alexander explained in detail: http://www.m4carbine.net/showthread.php?t=28296&highlight=headspace%2A Thank you, that was the most helpfull post, I should have looked there, at least people are not dicks about someone asking a question over there. This and the fact that checking headspace is not even required on an AR for the most part and if you do it the EXTRACTOR should always be removed. More logic to be used is why would you think a primer strike has anything remotely to do with headspacing anyway. That will never add up. If I was you I would put it back together and run it and never look back. |
| I'm sorry, my quesion was poorly written. This is the first time I have noticed firing pin marks on the primers of any ar. I did not mean to relate it to headspacing, the other quesion was the weapon not wanting to close on a go gauge. But I have been set straight on the issue. I will be shooting it this weekend to sight it in. And I did have the names confused in my head on the ejector and extractor. But I did not remove either one. If I have issues I will be sure to look remove them and re test. And outdoorsman, my commen was not directed towords you, thank you for your post, as it cleared up my question about the primer marks. |
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I'm sorry, my quesion was poorly written. This is the first time I have noticed firing pin marks on the primers of any ar. I did not mean to relate it to headspacing, the other quesion was the weapon not wanting to close on a go gauge. But I have been set straight on the issue. I will be shooting it this weekend to sight it in. And I did have the names confused in my head on the ejector and extractor. But I did not remove either one. If I have issues I will be sure to look remove them and re test. And outdoorsman, my commen was not directed towords you, thank you for your post, as it cleared up my question about the primer marks. Well I am sure when you take it out it will be just fine dude. AR's will ding the primer just a tad, but not nearly so bad as some of my chicom rifles do  Just enjoy your rifle and dont get too technical with it. I wouldn't if it was mine. I built a few FALs and had to do headspacing but the build with them is far more difficult than an AR. Some people here want to help you and some people just like busting other folks balls. I personally just wanna see you take that rifle out and have fun at the range and give a report back. And put those guages away you wont even need them for at least 20k rounds and then I doubt you have problems.
Anyway, good luck |
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