Oddities of 308 BCG's - with pictures. Now with Aero/Toolcraft comparison. - Page 1

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[ARCHIVED THREAD] - Oddities of 308 BCG's - with pictures. Now with Aero/Toolcraft comparison.

Posted: 7/25/2016 5:22:10 PM EDT

I recently purchased a Toolcraft 308 bolt carrier group. I'm using this BCG with a Krieger 6.5 barrel I ordered a few months ago so I had to strip the bolt down and mail it to Krieger for head spacing. I noticed a few interesting features of the Toolcraft 308 BCG and I'm kinda wondering how other manufacturers have handled these parts. First off I noticed the extractor has two O-rings and the ejector spring is different from 5.56 springs. Here is a picture of the 308 parts.

I went ahead and pulled out some AR15 parts to compare the ejector spring, Viton O-ring and ejector springs. We can see Toolcraft appears to have used fairly standard Viton O-rings. Their extractor spring is a heavy 5 coil design similar to the Sprinco I pulled from my spares box. I also grabbed a standard extractor spring off of a spare extractor I had laying in the parts box. While examining the 5 coil extractor spring from the Toolcraft bolt, I noticed it doesn't have a rubber insert, it has a secondary extractor spring inside the primary spring.

I took this close picture of the 308 parts showing the nesting springs.

Anyone know how other companies have handled the increased extraction and ejection needs of the 308 type rifles?

ETA: This morning I pulled out my Aero 308 BCG and did a little comparison of some of the small parts. The Aero bolt uses a similar nested extractor spring design with dual O-ring's. In these pictures the Aero parts are on the left, the corresponding Toolcraft parts are on the right. The tip of the Toolcraft firing pin is a larger diameter than Aero's. I think Aero may have went for the smaller diameter for less high pressure problems similar to the JP high pressure bolt. It's about .007 smaller in diameter. The Toolcraft firing pin appears to have about .010 more protrusion, I'll have to wait for my bolt to come back so I can confirm this. The Toolcraft pin is definitely longer and has .010 more length before you hit the firing pin stop.

I installed the Toolcraft extractor into the Aero bolt. It was a little more difficult to get the pin in but it appears to swap in and work. I clipped a round of 308 under the extractor and let the ejector throw it out without any problems. I didn't install the Aero extractor in the Toolcraft bolt because it's on the way to Krieger.

Here are some comparison pictures of the carriers. As you can see, Toolcraft has milled more off and appears to have left a sear trip in the profile. The Aero carrier is on top in all of these pictures.

Next I put them both on a scale. The Toolcraft is a bit lighter.

Posted: 7/25/2016 7:35:05 PM EDT

[#1]

308 game..............nothing standard..................

Posted: 7/25/2016 9:19:44 PM EDT

[#2]

I like the spring in spring design....it omits rubber....but with two O-rings.....we're still knee deep in rubber!!!! LOLOL!!!!

Like the above poster said....welcome to the word of .308 ARs.......

Now, to keep on topic....

Both my JP and my CMMG .308 bolts are pretty standard. Extractor spring with rubber insert and an O-ring assist....same with my roomie's Armalite which is a good ten years or more old.

To me, those Toolcraft parts look pretty nice. I'd hate trying to get that extractor back in the bolt, however....OWWWWW!!!!

Posted: 7/26/2016 12:14:22 AM EDT

[#3]

Thanks, I was looking at their BCG. That bolt and extractor appear to be nicely made, is the bolt carrier nicely machined as well?

Posted: 7/26/2016 9:43:30 AM EDT

[#4]

Quote History

Quoted:

Thanks, I was looking at their BCG. That bolt and extractor appear to be nicely made, is the bolt carrier nicely machined as well?

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I have no complaints so far. The new Toolcraft carriers are serrated on the side. The picture on Joe Bob's website didn't show it, but the carrier had them. I was happy they did as I plan to pair it with an Aero upper and the serrations should allow the forward assist to work properly.

I need to pull out my AIM and Aero 308 BCG's and do a comparison thread. I haven't stripped either one of them yet.

Posted: 7/26/2016 10:10:34 PM EDT

[#5]

how about KAK industries ? they went with dual ejectors and i almost want to try one but worry the dual ejector would weaken the bolt head ?

reviews are good though.

https://www.kakindustry.com/lr-308-parts/kak-industry-head-308

Posted: 7/26/2016 11:44:55 PM EDT

[#6]

Quote History

Quoted:
I have no complaints so far. The new Toolcraft carriers are serrated on the side. The picture on Joe Bob's website didn't show it, but the carrier had them. I was happy they did as I plan to pair it with an Aero upper and the serrations should allow the forward assist to work properly.

I need to pull out my AIM and Aero 308 BCG's and do a comparison thread. I haven't stripped either one of them yet.

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Quote History

Quoted:

Quoted:
Thanks, I was looking at their BCG. That bolt and extractor appear to be nicely made, is the bolt carrier nicely machined as well?

I have no complaints so far. The new Toolcraft carriers are serrated on the side. The picture on Joe Bob's website didn't show it, but the carrier had them. I was happy they did as I plan to pair it with an Aero upper and the serrations should allow the forward assist to work properly.

I need to pull out my AIM and Aero 308 BCG's and do a comparison thread. I haven't stripped either one of them yet.

Thanks, I look forward to seeing the comparison. The Toolcraft and the Rubber City BCG are the two I'm considering at this point.

Posted: 7/27/2016 9:39:26 AM EDT

[#7]

Bump for more pictures.

Posted: 7/27/2016 1:58:03 PM EDT

[#8]

Quote History

Quoted:
how about KAK industries ? they went with dual ejectors and i almost want to try one but worry the dual ejector would weaken the bolt head ?

reviews are good though.

https://www.kakindustry.com/lr-308-parts/kak-industry-head-308

View Quote

I've got one and it's been great so far. I'll try to remember to post some close up pics later.

Posted: 7/27/2016 2:05:57 PM EDT

[#9]

Quote History

Quoted:
I've got one and it's been great so far. I'll try to remember to post some close up pics later.

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Quote History

Quoted:

Quoted:

how about KAK industries ? they went with dual ejectors and i almost want to try one but worry the dual ejector would weaken the bolt head ?

reviews are good though.

https://www.kakindustry.com/lr-308-parts/kak-industry-head-308

I've got one and it's been great so far. I'll try to remember to post some close up pics later.

I'm looking forward to your pictures. If you don't mind, can you mic the diameter of the firing pin tip? I would like to see how it compares to my Aero and Toolcraft. Next I need to find someone with a JP high pressure bolt.

I went ahead and made the kak link hot. https://www.kakindustry.com/lr-308-parts/kak-industry-head-308

Posted: 7/27/2016 11:04:21 PM EDT

[#10]

thank you for making it live, i have tried and just cant figure it out. i am old and technology eludes me sometimes.

Posted: 7/29/2016 4:48:12 AM EDT

[#11]

I took detailed pictures of my Armalite AR10 carrier the other day. But the photo bucket app refuses to work. As soon as i get them hosted, I'll post up for another variable to throw in the mix.

Posted: 7/29/2016 9:16:09 AM EDT

[#12]

Quote History

Quoted:

I took detailed pictures of my Armalite AR10 carrier the other day. But the photo bucket app refuses to work. As soon as i get them hosted, I'll post up for another variable to throw in the mix.

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Thanks. I'm looking forward to seeing them.

Posted: 7/29/2016 10:39:29 AM EDT

[#13]

I finally got some pictures taken of my AIM 308 BCG. First for the weight:

Here is the weight of the bolt and associated small parts. I'm using a POF rollercam on this build, but it should be within .1oz of their standard cam pin.

Here is the AIM bolt next to my Aero bolt. AIM is on the right.

Here are pictures of the three carriers side by side. Top to bottom is Aero, Toolcraft and AIM.

Posted: 7/29/2016 5:36:00 PM EDT

[#14]

Are the carriers different length, or is this angle issue with the picture? All 3 have different sized trigger slots. Lots of variations.

Posted: 7/29/2016 5:39:43 PM EDT

[#15]

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Quoted:

Are the carriers different length, or is this angle issue with the picture? All 3 have different sized trigger slots. Lots of variations.

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They're the same length. As you noticed, they have a lot of variation. I would like to know who is cutting AIM's bcg. I used to think it might be toolcraft.

Posted: 7/30/2016 2:44:13 PM EDT

[#16]

In all the DPMS patterned .308 BCG, the extractor pin stands proud of the front of the BCG face.
I had one walk out on me. I peened the top slightly so it stayed put but I can still break it down for cleaning.
It's an issue in the design.

[ARCHIVED THREAD] - Oddities of 308 BCG's - with pictures. Now with Aero/Toolcraft comparison.

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