Thanks for the permission. I want to buy a replacement/spare BCM bolt, and I have a slightly used Colt M4 upper. I just want to make sure the replacement/spare is good to go. I know given the quality of both Colt and BCM that it most likely won’t be an issue, but after researching the topic, it seemed like a worth while expense (only 30 bucks).
Thanks to the rest of you who actually gave productive replies.
They don’t check headspace with a chamber gauge, they use a “Master Bolt” because they know what they are doing. Imagine that junior. You’re learning something everyday and one day you might just grow up to be a real boy.
Are you saying a manufacturer has never made a mistake? Unless the “reputable manufacturer(s)” are all staffed by machines, then there will be mistakes made as people are human and prone to mistakes. It is a fact of life. A lot of people will never build their own rifles but since this is a “Technical” forum, then I am guessing that a lot of folks on here will either be looking to build their own rifle or have built or are building their own rifle. If they are doing that and don’t buy an upper with a bolt and barrel that have been setup already, then they may want to do it. Most times it will be safe with out the gauge but $30 to ensure safety is money well spent.
Sometimes, the old dogs need to learn new tricks and think outside of the box to avoid injury to themselves or someone else. Blanket statements don’t always work and don’t always fail.
So tell me where you born an ass or did you have to work at it?
Really a “master bolt”. And I guess the Military uses a “master bolt” when they change a barrel, or do an annual inspection. There are a lot of reasons to use and need a headspace gauge. You obviously have no clue, so why don’t you do like the wise old owl and talk less and listen more.
BTW any asinine response you may have I will never see, because I put you on my ignore list.
Let’s tone it down shall we. There are obvious needs for checking the headspace. People may swap a barrel or bolt around within various rifles/carbines that they have, or they may have an older weapon and want to upgrade the bolt.
I personally have checked the headspace of every carbine/ rifle that I have bought or assembled, regardless of the manufacturer.
Thanks for all your imput in this and other tech threads IG. It has helped me better understand how to maintain not only my personal carbine, but my dept. issue as well.
And just who the hell are you MK18??? If you can’t provide constructive commentary without being a DICK hit the road and don’t come back. Take your attitude with you.
You need to adjust your foil hat a little to the left there Newbee. On the forum for one day and already trying to throw your weight around eh?
Nice try but newbie for this forum or not I can spot an idiot when I see one. Your posts are ample evidence that you’re a loud-mouth with a complex.
He’s right, alot of your posts seem “smart A#$” to me. And you are hardly a veterano with 94 posts (not that post count indicates alot).
This place going the way of TOS?
it has been for some time, luckily the ignore function works pretty well except for quotes. I suggest some of you make use of the ignore function.
So which gauge is the best to use, field, go, or no-go? I think I’ve read that you can use all three to get the best info, but I really don’t want to spend 90 bones for all three.
Then get a “GO” to make sure you can chamber the longest in-spec cartridge, and get a “FIELD” to make sure it is safe to fire. The “NO GO” is more for setting headspace (or matching a bolt to a barrel). I have the Forster 5.56 (not .223) GO and NO GO gauges. They work on both my AR’s properly - close on the GO, don’t close on the NO GO.
I recently bought two spare bolts and matched them to the barrels in my two carbines - one bolt wouldn’t close on the GO in one carbine, and the other will barely close. In the other carbine, both spare bolts closed on the GO. This highlights the effect of tolerance stack-up and why it is good to check.
I’m not really worried about the spare bolt that barely closes on the GO, because with a little shooting, the lugs will “set” in place under recoil and open up the chamber length slightly.
Just a follow up, I ended up buying the Bushmaster field and it is very easy to use. Pop off the ejector, reassemble the BCG, insert field gauge into chamber and attempt to send BCG into battery buy pushing the rear of the carrier with moderate finger pressure to overcome the ejector spring and force the face of the bolt right up against the gauge. If it does not close, and the back of the carrier is sticking out of the upper receiver, you are GTG.
Thanks for the info guys!
You could solve the problem of continuing to shoot a gun with excessive headspace, after you’ve put many rounds through your reputable manufacturer gun. Even good guns wear out.
Unless you own a machine shop full of high dollar tools, there is nothing you can do with any information provided to you by head space gauges.
What are you talking about? If a gun chambers a FIELD gauge there is plenty one can do with that information. Stop using the gun for starters, then order a replacement bolt, and if it still fails then rebarrel it too.
Somewhere in the 90s I re-barreled a Colt Sporter Match using a 14.5" Bushy with permed brake. I wanted a shorty and this became my “CAR”. I’ve always been concerned about the headspace on this gun and despite using HS gauges for setting headspace on FAL builds and checking C&Rs I never got around to ordering a set in 5.56.
Flash forward to the present and a desire to upgrade equipment and the original bolt carrier group for the Colt Match (previously used in another build) is now back in the “CAR”. I have not even function fired it yet with the Colt bolt - and if I did so in the past I don’t recall.
I decided to get a feel for the headspace on the CAR right now using what I have available and I found the effort to be worthwhile. The Noveske complete upper I bought was used as the baseline.
WECSOG Headspacing:
Note: Despite sleeping in a Holiday Inn Express, I’m not a gunsmith. Futher, I do not recommend using live ammo for checking headspace, despite doing so myself.
For field expedient GO gauges I used A) resized IMI dummy round with the sizing die set to minimum or slightly below minimum based on a .223 case gauge; and B) factory 75gr Privi that indicated near minimum size in the same case gauge. Factory IMI M193 would work as well - it appears to me to be sized at minimum.
My factory 75gr TAP .223 (#80265) happens to measure near maximum size in the same case gauge and it became my “not-quite” NOGO gauge.
Noveske Baseline:
I used a Noveske complete upper for a baseline. The upper was removed from the lower for safety. The extractor was removed from the Noveske bolt, but not the ejector. The barrel was cleaned after the last range session and the bolt and carrier were free of any excess lube. The N4 has approximately 600 rounds fired since being purchased last month.
The slightly excess-resized IMI dummy round closed with no noticeable pressure other than to overcome the ejector spring. The bolt snapped into battery and unlocked easily.
The factory Privi round closed with lite to moderate pressure. No undue force was required to unlock the bolt.
The TAP round required moderate to somewhat heavy force to close the bolt. The bolt would Not unlock by hand - I had to lightly tap on the charging handle with a nylon hammer to remove the round. FWIW, I’ve fired exactly 80 rounds of the TAP .223 in the Noveske with zero issues.
Note: While here I also checked a spare (new and unfired) BCM bolt carrier group and it indicated tighter initial headspace than the Noveske BCG. No problems closing or unlocking the bolt with my “GO” rounds, but the TAP round required very heavy thumb pressure to close, plus unlocking the bolt was more difficult than using the Noveske. The Noveske has had time to “wear-in” so the comparison my not be relavant.
CAR Checks:
1). Both the resized IMI dummy round and the factory Privi round closed easily using the original colt bolt (sans extractor) in the Colt Upper /w BM barrel. Unlocking the bolt was normal for my “field expedient” GO gauges.
2). The TAP .223 round closed with moderate-, but quite noticeable pressure. It required moderate force to unlock the bolt as well - very similar to unloading an unfired round at the range - where a bit of a “yank” on the charging handle is needed.
Using the BCM bolt carrier group, I was not able to close the bolt on the .223 TAP. The IMI dummy and the factory Privy close with no noticeable pressure (other than to overcome the ejector spring). The bolt unlocked with the dummy round with no pressure while the Privi did require some light force to unlock the bolt.
Conclusions:
I’m confident the headspace on the CAR, while not as tight as the Noveske, is safe for me to shoot. YMMV
A full set of 5.56 HS gauges (GO, NOGO and Field) is on my want list.
YMMV and all that.
You clearly have no idea what you are talking about. Like your ass, you couldn’t find head space with both hands. You would have to assume that your chamber was reamed correctly from the manufacturer and have a MAX REJECT GAUGE to even get an idea of the condition of your barrels head space.
The bore on my Colts will be shot out long before I have any head space issues. This whole thread is an attempt to justify purchasing a tool that is a complete waste of money and causes more errornet issues than it solves. Like I said, keep sending Mark Brown your money and he will keep making garbage ass tools.