Who actually makes the bolt in the BCG?

AR/M4 AR Technical Discussion
1

Question for those in the know:
As title asks - who actually makes the bolt?

Recall reading that a “batch” of 158 carpenter steel costs something in the range of $500.000, based on which I assume only a limited amount of manufacturers actually have the means to purchase and manufacture the bolt.

And what about the carriers and other parts?

Is there some magic castle in the sky that machines all the bolts (and carriers), which then “fall” to earth for all the manufacturers to put their finishing touches on (gas key, staking, HP/MPT etc etc).

Based on this info, aren’t all BCG’s more or less identical in origin, but the parts/testing used during final assembly is where it all happens?

Or am I completely misguided and misinformed?

(by the way - this is not a question why or not HP/MPT is redundant…:wink: )

2

There’s probably just a few manufacturers… the question would likely be to the customer… “what do you want done to the bolts and how do you want them marked?”

Then the bolts that fail a QC check probably go to the bottom feeder companies… etc.

3

So it would be safe to assume that there’s virtually no or little difference between a BCM, DD or even Colt BCG - other than the logo…
Is the info about the carpenter steel correct, or just another internet fish wives tale?

4

No. I’ve noticed that the COLT finish on my Colt bolts is tougher. I’d run any of those bolts though.

5

I have been lead to believe that there are variances allowed in the TDP IF the manufacturer can prove that the material they are using is equal to or better than what the spec calls for.

So I think Colt differs in some areas and is why their products are better (in certain areas) than other companies. I imagine this is why they would sooner NOT compete in a contract than have to share their knowledge with a competitor (assuming that it is a multi-award contract and everyone has to share the TDP).

C4

6

I don’t quite think you understand what ordering metal means. There is many variables to look at, such as density, truness, quality etc. Just because you buy type “A” such and such type of material, doesn’t mean it will be quality. You will find this out if you ever have to deal with buying stainless etc stock metal.

B: the logistics. It may cost 500$ to buy, but can cost an additional 1k to ship. Metal is heavy, especially SOLID metal.

Also, provider means a lot, as this goes back to my original ordeal. Quality. Ordering from a shit provider means you will most likely get shit as a result. Bolt makers don’t skimp, they generally buy from top end providers, and pay a premium on metal, due to the fact it was all made in top tier company locations.

Also, shipping. Sure you can buy a massive rod (they generally come in rods, but heck, you can buy square solid as well, just expect a massive amount of cost to machine the square metal down to round), you have to take into matter of the rod being bent, which is generally what happens when ordered from a dealer. If the OD isn’t enough, there is no way to true it to straight flat. IE the smallest defect in curvature can basically make your buy go from hopefull, to holy crap I just wasted all that money, plus leaving you stick with a massive rod, or many chunks of metal. This leads me to the other part, and that’s when buying bulk almost no company cuts it down without a decent cost, into sized pieces. This is the worst thing to do, as if it’s not true, it can ruin many, MANY pieces. Remember, when a bolt MFG takes a massive rod and cuts it down, they can make trueness per bolt cut on the actual rod, thus eliminating as much out of wack metal as possible. All things to think of.

IMO, if a company can’t get metal, they can’t get it. If you can get something, it’s most likely metal a company has skipped on. And last, having a company that makes bolts themselves make custom bolts just seems bas-awkards, as if it was beneficial they would already be making them, themselves.

Just my 2 cents.

7

I’m kind of confused by your last statement. Just for clarification, do you think the KAC E3 bolt is not beneficial?

Or do you mean something like asking DPMS to make a 9310 bolt is stupid?

8

As for the KAC E3 bolt, no clue, never used one. What I said had no meaning about whether something is good or not.

I meant contracting a company to make a slew of bolts for you seemed rather strange, and IMO many companies would probably just sell their own stock of bolts, rather than just make some for someone. Generally a company uses their own distributors and sources for metal, to assure their reputation isn’t ruined due to some variable that could arise from someone else sourcing the metal for them.

And asking a company like DPMS? hell yea that’s stupid. LOL. It’s DPMS. I wouldn’t ever have any such company custom one, when they can’t even build their own brand ones right.

I did slightly mis-read the OPS original post though, as I was reading the article on my phone, and not on my larger screen. I see now he wasn’t talking about buying stock and having someone do something, so in that case, my post is pretty much meaningless anyways.

9

Removed by Suwannee.

10

Thanks for the clarification. And DPMS was just an extreme example.:happy:

11

Your post actually made me re-read the OP’s post and notice my error. LOL, definitely mis-read it at the very least =] O well, shit happens.

12

Regardless misreading the OP, as you do seem to have some real world insights perhaps you could enlighten us and share some of your insights going back to the original question. For instance - what is the deal with that Carpenter steel, and for that matter, manufacturing in general ?

From a consumer perspective, we pretty much know “all” there is to know about receivers, barrels and who makes what and why some are better than others, but when it comes to BCG’s, we’re still somewhat in the twilight zone. An understatement, considering it’s importance in the scheme of things.

One pretty much has to surrender oneself to whatever brand-name is put on it, without knowing much about the manufacturing process, and why some are better than others, based on nothing other than reputation.
Which is pretty effective, but not very objective, it seems.

Apparently just like barrels, there seems to be a healthy balance between art and science, but this is just hearsay, would love to get some factual info.

13

158 Carpenter is a trade name, it’s P-6 mold steel. When you say “batch” you are talking from the mill, so what is the least lbs you can buy at what price ? Anything less you go to the distributor.

14

Here is a post I ran across on a machinist forum that may either satisfy or pique some of your curiosity.

Does anyone know of a “more-readily-available” alternative to Carpenter’s Alloy 158?

We are currently making bolts for a very large AR-15 manufacturer. I have had several other smaller firearms companys contact me looking to purchase these bolts. But the material that we are currently using is supplied to us by our customer. The Carpenter 158 has to be purchased in 20,000 Lb lots and is roughly $5/Lb.

So I was wondering if there was another type of material out there that had the same chemical properties as the Carpenter 158, but could be purchased in smaller quantities (i.e. 1000 Lbs?) This is 3/4" dia. round bar stock.

It would appear that in at least this instance the weapon manufacturer paid for and sourced the material for the contracted machine shop to produce the bolts.

15

good bolts seem hard to come by these days

16

They can be, but we have LMT bolts in stock now!

http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=L7A3B

C4

17

Is the info about the carpenter steel correct, or just another internet fish wives tale?

18

Luke_Y’s quote is a great thing to remember the next time someone says “these are made by the same people that make ___________'s!!!”