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View Full Version : Bolt Carrier Group Guide (and questions)



Stickman
10 March 2008, 19:27
Currently I'm working on writing up and finishing pictures to a Guide on various Bolt Carrier Groups. My thought on this is that there seems to be a lot of different talk about BCGs, and their different designs. I hope that some of these questions will be answered, and that people will be able to get a quick visual reference. However, I can't help but wonder what people are really looking for with a guide like this.


How much detail do you think the average reader is looking to find?

What info are you looking for?

Is there a particular BCG, or BCGs that you would want to see in this?

12131
10 March 2008, 21:12
Beside the typical staking issue that comes up from time to time on various forums, I want to know how to tell which BCG comes from which manufacturer, because you don't typically see their name on the BCG (except Young and POF). Also, how can you tell which BCG is MP tested, if the MP label were not on the BCG itself?
Thanks.

Stickman
10 March 2008, 21:33
12131,

Hopefully the pictures will help with determining MFG, but many of the carriers appear to come from the same place.

Right now I've got pictures of:

CMT
LMT
LMT Enhanced
RRA
Young MFG


I'll be adding pictures of:

Bushmaster
Colt
Olympic Arms

12131
10 March 2008, 23:24
Thanks, Stick. Is Bravo's BCG made by Bravo?

SHIHAN
10 March 2008, 23:28
This is a tough one as like you said some of them come from the same place. I have seen different carriers by the same manufactuers. Pics showing what parts are used on different carriers would be a good addition. Let me know if I can help in any way.
Chris

Paulo_Santos
11 March 2008, 02:39
There is also the LWRC. If you can, can you include which steel they are made of?

Stickman
11 March 2008, 08:34
LWRC and Bravo are two companies I hadn't initially thought of. If they are interested in getting a BCG out here, I think it would be worth including them.

More importantly than making them, I believe Bravo Company has them made to their specs, and its my opinion that the specifications are more important than who actually produced the end product.



Here are a few sample pictures of the Young MFG BCG. The others manufacturers BCGs will be shown in similar pictures.


http://stickman.rainierarms.com/galleries/WeaponEvolution.com/IMG_1411%201028%20WEVO.jpg


http://stickman.rainierarms.com/galleries/WeaponEvolution.com/IMG_1412%201028%20WEVO.jpg


http://stickman.rainierarms.com/galleries/WeaponEvolution.com/IMG_1432%201028%20WEVO.jpg


http://stickman.rainierarms.com/galleries/WeaponEvolution.com/IMG_1433%201028%20WEVO.jpg

Stickman
11 March 2008, 08:37
SHIHAN- Do you mean a break down of the individual parts of a BCG so people know what they are? Similar to a schematic?


paulosantos- I'm not sure that all companies will be willing to give the details, but I think its worth a try. I understand that there are people who already have this information, but I would need to clarify from them how they discovered their info. I don't want to write it out unless we can determine its factual, and there have been plenty of people who have posted things with good intentions only to find out later on they are incorrect.

John Hwang
11 March 2008, 09:11
Just an FYI for clarification

The Young MFG BCGs DO NOT come staked from the factory. They use red locktite which have survived 10,000 round tests by Young. The staking was done at our shop as the additional insurance was beneficial.

SHIHAN
11 March 2008, 09:42
SHIHAN- Do you mean a break down of the individual parts of a BCG so people know what they are? Similar to a schematic?



paulosantos- I'm not sure that all companies will be willing to give the details, but I think its worth a try. I understand that there are people who already have this information, but I would need to clarify from them how they discovered their info. I don't want to write it out unless we can determine its factual, and there have been plenty of people who have posted things with good intentions only to find out later on they are incorrect.

Hey Stick I ment a break down of what the individual parts are. Such as screw type used, chrome lined key etc.

Stickman
11 March 2008, 12:42
John, that info will be included in the writeup.


Shihan- Not a bad idea at all. I need to contact some of these companies and see what info they are willing to provide, or what info they know.

12131
11 March 2008, 12:51
Anyway, will your final write-up be in the form of a summarized table, you know, something similar to "The Chart"? [BD]



12131- I meant to reply to your post, and accidentally edited it. I didn't want you to think we were playing with your post, I was simply clumsy with my fingers. Sorry about that!

Stick

Stickman
11 March 2008, 13:56
12131


The information in "the chart" is geared more towards an entire weapon, while this guide is dedicated towards just the BCG. I'm not sure at this point if a spreadsheet is something we want to do or not. As it progresses, and all the info starts coming together, we'll have to take a look at it.

Stickman
11 March 2008, 13:58
Hey Stick I ment a break down of what the individual parts are. Such as screw type used, chrome lined key etc.


Good idea, it may link back to what 12131 just asked. I'm not a fan of spread sheets, but I'm not sure of a way around it. Besides, I am horrible with making charts.... which isn't going to help anything.

Paulo_Santos
11 March 2008, 14:25
paulosantos- I'm not sure that all companies will be willing to give the details, but I think its worth a try. I understand that there are people who already have this information, but I would need to clarify from them how they discovered their info. I don't want to write it out unless we can determine its factual, and there have been plenty of people who have posted things with good intentions only to find out later on they are incorrect.

It isn't a big secret, LWRC uses 9130 steel. If the other manufacturers don't provide the info, it is no big deal.

m24shooter
11 March 2008, 16:30
This looks great and would be an awesome reference for those that are building up guns or just want to increase reliability with enhanced-type BCGs. I would certainly like to see some info and confirmation from the different manufacturers, but they may not want to play.

Stickman
11 March 2008, 16:45
This looks great and would be an awesome reference for those that are building up guns or just want to increase reliability with enhanced-type BCGs. I would certainly like to see some info and confirmation from the different manufacturers, but they may not want to play.




Thats my concern as well. I can understand the need or desire to keep certain things quiet within the manufacturing community. However, the release or verification of solid information is always more desirable than the rampant spread of internet rumors.


What I may do is release the BCG Guide in an unfinished format, and then email the link to companies so they can see what we are doing. I don't want there to be any one thinking we are out to cause problems or sneak something in. I've got the listing written up of information that I would like to see for each BCG.

This way, a company can fill in answers as they see fit, and there shouldn't be any question as to how legit it is since its coming direct from them.

DepletedUranium
11 March 2008, 20:36
gonna be awaiting for the Young write up :)

Stickman
12 March 2008, 11:09
gonna be awaiting for the Young write up :)



So am I, there is a lot of information thats going to take some time to gather. I'm leaning heavily towards putting it up soon, then just updating it as I get the time.

DepletedUranium
12 March 2008, 12:06
So am I, there is a lot of information thats going to take some time to gather. I'm leaning heavily towards putting it up soon, then just updating it as I get the time.

Take all the time you need [:)], the release of the UBR should keep me at bay for a bit longer ;)

Paulo_Santos
12 March 2008, 14:35
Stick, I would try to contact Jesse or Darren at LWRC. They can be very hard to get a hold of sometimes.

jesse@lwrifles.com

darren@lwrifles.com

FYI: Your IM box is full [:D]

Stickman
12 March 2008, 23:44
Stick, I would try to contact Jesse or Darren at LWRC. They can be very hard to get a hold of sometimes.

jesse@lwrifles.com

darren@lwrifles.com

FYI: Your IM box is full [:D]



I'll have to do that. My IM box is cleared out now, I need to get one of the lazy admin to give me more space... [BD]

parabellum
13 March 2008, 14:18
I'll be adding pictures of:

Bushmaster
Colt
Olympic Arms

any chance of seeing pics of the POF DI BCG? Noveske pics would be good too, because you probably already have some from the N4 Light review.

Stickman
13 March 2008, 21:41
any chance of seeing pics of the POF DI BCG?


I spoke with POF the other day, and will include their POF piston BCG, but I didn't think they still made a DI BCG.

at4rxj
14 March 2008, 07:23
Stick,

Here are some pics I took awhile of a Smith Enterprises carrier I had (the bolt is FN)

I believe it was hard chromed. I no longer have it, but it was a great carrier when I did.

http://i162.photobucket.com/albums/t250/at4rxj/A2/DSC_0116.jpg

http://i162.photobucket.com/albums/t250/at4rxj/A2/DSC_0117.jpg

http://i162.photobucket.com/albums/t250/at4rxj/A2/DSC_0118.jpg

http://i162.photobucket.com/albums/t250/at4rxj/A2/DSC_0120.jpg

Stickman
19 March 2008, 21:58
I have posted a rough draft, and starting point for the BCG Guide. It can be viewed at the below thread.


http://www.weaponevolution.com/forum/showthread.php?p=2471#post2471

Eric
19 March 2008, 22:14
Excellent! I'm looking forward to any additional details that manufacturers might provide.

Cyclic240B
27 March 2008, 10:52
Sorry for being late to the party but what about the JP Rifles P/N JPBC-2 "Tactical Operating System"? I have always wanted to test drive one but seem to get derailed with other projects before I can purchase one. But by it's description it seems like a pretty nice bolt carrier, that offers a little more than the average BCG.

http://www.jprifles.com/buy.php?item=JPBC-2

"JP Full Mass Stainless Tactical Carrier with key installed.

For police tactical duty or any application where absolute reliability is the main criteria, we have our new TOS™ or Tactical Operating System with 416 stainless steel special design carrier that includes forward assist serrations and a dust cover notch. The bore of the JP stainless carriers has a roller burnished finish for frictionless operation with no chance of peeling chrome as in standard mil-spec carriers. The exterior bearing surfaces are hand polished. When properly lubricated, both systems make your rifle feel like it was cycling on ball bearings. Both carriers feature a 100% increase in bearing surface for smoother operation and improved alignment and lower wear in the upper receiver. Both are M15 semi auto configuration in the rear with the mil-spec longer cocking pad in the front for best reliability. This is hands down the best designed and highest quality general purpose carrier on the market. Sold as carrier with installed key or complete bolt/carrier assembly."

Stickman
27 March 2008, 11:15
Sorry for being late to the party but what about the JP Rifles P/N JPBC-2 "Tactical Operating System"? I have always wanted to test drive one but seem to get derailed with other projects before I can purchase one. But by it's description it seems like a pretty nice bolt carrier, that offers a little more than the average BCG.

http://www.jprifles.com/buy.php?item=JPBC-2




I don't know anyone at JP, but I would be happy to include it if we had one.

parabellum
20 April 2008, 00:18
The Young's BCGs look very nice.

I assume they are they MPI?

clayart
29 May 2008, 15:33
what does "staked" and "shot peened" mean?

TigerStripe
29 May 2008, 16:45
Staking is pressing a piece of metal into a screw that prevents the screw from becoming loose and being shaken or jarred out of place.
http://www.AR15Armory.com/forums/uploads/1210262474/gallery_384_42_47958.jpg
The portion surrounded by the square shows staking... very good staking.

Here (http://www.metalimprovement.com/shot_peening.php) is a good technical - scientific explanation of shot peening.



TS

kjd2121
2 February 2009, 09:19
I would like to know how a BCG affects accuracy. I recently read an article that basically stated that the BCG had nothing to contribute to the accuracy. Hmmmm, probably many opinions on this. Are there real world test to confirm?

If I were to order the YM Match BCG vs the regular chromed YM BCG what would that get me in terms of accuracy?

I want to build a very accurate AR. Your help is appreciated.

Curious to hear the responses.

Stickman
2 February 2009, 18:20
If you aren't handloading to very specific specs, I don't think you would ever see a difference. The bolt is either in battery, and locked up, or its not. When the bolt locks into the barrel extension, the carrier isn't doing much aside from waiting for gas to purge inside it and pull the bolt back out.

A poor carrier has its own set of problems, but thats another story in itself. High tolerances, and quality construction are important, but I would not expect much if any difference between group sizes by using different bolt carriers.


What sort of loads are you looking to shoot?

What distances?

What glass are you looking at using?

John Hwang
4 February 2009, 20:24
Just an FYI for clarification

The Young MFG BCGs DO NOT come staked from the factory. They use red locktite which have survived 10,000 round tests by Young. The staking was done at our shop as the additional insurance was beneficial.


I was corrected by a customer who spoke to Young and they are claiming that they haven't fired 10K rounds out of these carriers. So either I was given wrong information or I was mistaken. [BD]

Arms_Reach
7 February 2009, 16:32
Hey Stick,
I read through the entire post and like what you are trying to do. It is nice to have a place with accurate data.

That being said, I bought a YM NM BCG in DEC. In your pics/description you list a blue insert in the bolt. Mine came from Young (not another vendor) without the insert, but with an "O" ring.

Ryo
10 February 2009, 11:11
Here's a picture of a Y/M National Match BCG from Spike's Tactical. Apparently Y/M engraved the spider logo into the BCG for them. I had talked to Tom and if I remember correctly, he said that Y/M also staked it or them also.

Sorry for the poor quality picture..

http://i300.photobucket.com/albums/nn14/Ryo_Ohki2/IMG_1935copy.jpg

JustMatt
12 February 2009, 15:10
Whats the benefit to having a black oring instead of a black insert on the LMT bolt?

TehLlama
12 February 2009, 16:08
The O-ring spreads the shock out over a wider area, theoretically longer O-ring life and longer service cycle where it helps with extraction.
Practically speaking, as the spring wears out, drop in a new one with a fresh o-ring, and you're set. Bolts themselves won't go through more than a couple such replacements (if that), depending on firing schedule, so any of the above will get the job done - chamber specs, buffer weight and spring longevity are more pressing issues usually, a 5-turn extractor spring in good shape will do lots better than a worn out 4-turn.

JustMatt
12 February 2009, 17:29
Ok, so the O-ring acts just like the insert except it has a larger diameter. Gotcha, I wasn't sure if it was a LMT specific bolt thing or if I could do that to any bolt extractor.

cebuboy
24 February 2009, 03:39
Long time lurker here, if I may ask, what advantages can be had from a Young Manufacturing M16 National Match Chromed BCG vs their standard M16 Chromed BCG?

Its half an ounce heavier and has more bearing surface, does that make it more reliable than the standard chromed BCG?

Echo4Tango
14 June 2009, 01:46
Im with Cebuboy here, I think a great addition to this review would be to add a section that tells what these 'extra features' are, or more practically, what the manufacture's CLAIM it does. For example;

-The third gas venting hole is to increase reliability by lowering chamber pressures quicker than a standard BCG.

-The extra half ounce of weight is meant to slow down the cycle of operations to give the bullet more time to leave the barrel before parts start moving and there by increasing accuracy.

Obviously these are just guesses, but for the guys just getting into AR building or even the more experienced members out there that have just never had to deal with BCG's in depth before I think a section like this would help out a lot. Quite often the manufacturers themselves don’t tell you what their cool new innovations do, they just expect you to believe in them or trust that their product is better.

And I personally would also like to see a "Stick's Comments" section where you or the other Admin give your own personal experience with said product or feature because we all know that the manufacturer’s claim can often be vary far from real world performance.

The write up is great so far and now that I've just asked you to put 20 more hours into it Im going to shut up :o

niner
22 July 2009, 10:45
What is the difference in an M16 and AR15 BCG? I know ARFCOM says, but that site is blocked at work, and for some reason this one isn't :)

Stickman
22 July 2009, 22:07
The M16 carrrier is longer on the underneath, the AR15 version is shorter underneath, and will not trip the autosear.

mlosi762
25 August 2009, 06:57
Can you run an m16 carrier in an ar15? Or does that pose potential problems?

Stickman
25 August 2009, 08:45
No problems.

TehLlama
5 September 2009, 09:49
The primary reason to run the M16 style carrier (style emphasized) in an AR is to increase the mass of the moving components - as long as the gas port is in spec and the upper is properly lubricated, this means more reliable cycling, more manageable recoil, and more consistent in-battery completion. This paired with an H buffer in a carbine is part of a short-list reliability upgrade parts list.