Why do so many people insist on using a head space gauge for an AR15, and spending $400 on tools?

Question

I build ARs as part of my job at a local gun store where I work full time.... And I'm not sure what I'm doing wrong, but I've never needed all that stuff. 

When it comes to checking headspace.... Why? Has anyone ever found new AR parts that didn't headspace correctly? They are made to the same dimensions, and there is no way someone assembling rifles can change it. The barrel extension is attached to the barrel and torqued on very solidly to exacting specifications at the factory. Every bolt is made to fit every barrel extension. Because the barrel extensions, where the locking lugs connect, is attached to the barrel... You can't take off some of the breech and rechamber to correct headspace. 
The parts are made to fit..... Modern manufacturing techniques allow this to be so. We have never tested the headspacing in a rifle prior to test firing it, and we have never had one show any signs of over-pressure. Maybe this is because we use quality parts that are made within specifications... But, has anyone else ever had an AR assembled from brand new parts fail to headspace correctly? 

Also, how are people managing to spend so much on tools, unless they're just so lazy and gullible that they must spend $50 on every gimmick that comes out? Just yesterday, I heard $400 in specialized tools... That's insane. To assemble a lower, you need a multitool. DPMS makes one that's about $25. A razor blade comes in handy for holding in detents while parts are placed, although it isn't really necessary. 

For the upper, you can either use the Brownell's clam shell type, which we use on new builds. Or, you can use the DPMS "claw" for rifles that already have an optic on them if you're replacing a barrel or something. For the average person, the "claw" is more versatile. They cost around $40. You could even go cheaper and get a block of wood that fits the mag well, and clamp the wood in a vice... It isn't the best, but it can be made to work for the home builder who just needs it once. 

Other necessities are hardly "specialty" tools. A few punches... Most people probably have those, or could borrow the necessary ones from a friend... Punches are not specialty tools, a cheap set is not expensive at all, and they're good to have on hand. 

Beyond that.... a torque wrench is a nice addition, but really isn't necessary for the home-builder. Just make sure everything is snug. 



I will admit.... With all the various tools we have for building rifles, the pivot pin installation tools and several types of wrenches for the various rail systems, etc., we probably have $400 or more in specialty tools. However, this is by no means necessary for the average person to put together a rifle at home. To a hobbyist trying to save some money building their own custom rifle... Efficiency is not the issue. If you don't enjoy building the rifle, buy one already built... I can do it faster than you can. If you enjoy it, though, and have a budget.... What's the point in spending a ton on tools to get it over with? Take your time, enjoy your hobby...

Who wants to tell my how wrong I am?

Al · Accepted Answer

Colter;

As a professional gunsmith of over 30 years experience, I have to agree with most of what you posted. I cannot TELL you haw many times I was forced to built a specialty tool just to get one job done, without having to send off for some exotic (and expensive), specific tool. Heck, I once fabricated an oversized leaf spring vice for a wheelock musket (17th Century). Took me about twenty minutes worth of work with some scrap stock and a couple of wing screws. An outfit in New England wanted to sell me one for 200 clams!

But...

No gunsmith, no matter how confident, should EVER be without a complete set of headspace gauges. If a customer shows up with a rifle in a caliber for which you don't have a gauge, either suck it up and buy the correct gauge, or be honest and send him on his way. Your customer trusts you, but NEVER trust parts that you did not make yourself...even then, you still need to be assured of correct headspace with EVERY rifle you send out.

If your work is limited to a single caliber, then you are out the expense of three gauges ("go", "no go" and "field").

I have two entire drawers of a Snap-On top box devoted to nothing but sets of headspace gauges, sorted by caliber...many of them of obsolete cartridges (the gauges themselves are antiques), that I gleaned at gun shows, the internet and other sources.

bynd · Answer

Tools Needed To Build Ar 15

Erika · Answer

Headspace Gauge

Anonymous · Answer

I have 6 AR's.  I built 2 of them.  The only AR specific tools I own are, (1) DPMS Armorers Wrench, (5) A2 Front Sight Tools, (1) Handguard Removal tool (black rubber coated, can't remember what brand.  

But just this evening I ordered a CRT-15 carbon removal tool.  I am hoping that it will save me from the dreaded pick trying to clean out the bolt carrier.  We shall see.

Anonymous · Answer

For the best answers, search on this site https://shorturl.im/Yf9EB

The M-16 and M-4 are both direct impingement. The HK 416, which is used by special forces, is piston operated.

Anonymous · Answer

Just a quick OPINION here that I know will not be chosen as best answer but...

There are certain terms that are way overused in the shooting sports industry.  And one of them is "head spacing".  Most folks have absolutely no idea what it really means (and it actually means different things, depending on the firearm and caliber).

Another favorite of mine is "minute of angle".

??? · Answer

For a standard AR15, you are probably correct that it is un-necessary, but I do it for match quality barrels, just to make sure that they are precise.  Really good accuracy is like a formula one car- the closer and closer you get to perfect, each small step you take to get there costs more money.  Sure, it is cheap and easy to get to 'good enough,' but 'perfect' takes more time, more work, and more loot.

David S · Answer

I have personally built 3 ARs in the last few months.  One SPR, Two carbines.  Most of the parts came from Bravo Company Machine

As far as tools go, i used:
Upper block from Adcofirearms.com  $30
Multi tool For barrel nut, flashhider, and receiver extension castle nut- from Aimsurplus $25
Torque wrench- (borrowed from an autoparts store) optional ..see instructions below
Grease -for barrel nut threads $4 (now I have enough to build 100s of AR-15s and grease my Garand
Cheap Strap Wench- (I used free floated handguards) $5 bucks from Harbor Freight
Vise already had several (live on farm)
Allen wrenches for low profile gas block - already had some

If you are using the standard Front Sight Base tower, then a set of punches would be needed along with a hammer

For the lower
Used multi tool from above for castle nut
Vise-grip (cheap on from harbor freight) to push in roll pins on the lower. $3


Instructions form ar15.com---- Free and easy to follow.  
http://www.ar15.com/forums/topic.html?b=3&f=4&t=226782

So my total for tools was around $65, and I wouldn't call any of them "specialized" except for the multi-tool and upper block.  


I would love to hear what special care or techniques Glacier puts into building his "match rifles".

sirbobby98121 · Answer

Hey - as long a SHE can buy shoes, I can buy new tools.


Problem?


:-)

Trending News

Why do so many people insist on using a head space gauge for an AR15, and spending $400 on tools?

9 Answers