Brownells 6.5 Grendel BCG...????

[Chance-dg]

Bought a Brownells 6.5 Grendel Type 11 BCG for my WC barreled build. Read a couple of threads on this BCG with too short a bolt. <2.820. Measured this bolt and sure enough the bolt is 2.793 long ( measured 3 times) with a firing pin length of 3.265.

My Monster bolt is 2.820 of course with a firing pin length of 3.282 using a Bravo Co. Ion Bonded BCG with the 5.56 bolt replaced with the MONSTER Bolt matched with a MONSTER GB 16 in. barrel and everything plays well together.

What are the ramifications of using the Brownells Grendel BCG as is with my WC barrel?? Should I return the Brownells BCG and either purchase a Wilson Combat Grendel BCG ($225,00 and out of stock). Or get another MONSTER Bolt and get a different carrier group? I have not heard good things about Tool Craft BCGs but have no experience with them.

I have not fired this weapon yet as I just finished (I thought) building it.

Any info and advise/recommendations are appreciated. I have gotten so much great info and advise from other members and obviously have much to learn.

Thanks to all

[VASCAR2]

https://www.brownells.com/gunsmith-tools-supplies/measuring-tools/firing-pin-protrusion-gauges/firing-pin-protrusion-gauge-prod26477.aspx

[Chance-dg]

Thank you....I too am too cheap for the WC BCG......I am going to remeasure my bolts and firing pins tomorrow when my eyes aren't tired and reverify everything...then I am going to call Brownells Monday morning (I have had a vendor account with them for almost 20 years) and get it straightened out, get the Monster bolt and a stainless FP and make everything in spec. plus measure all my other 5.56 bolts and FP's and make some notes in my journal.

I don't ever tear down more than one BCG at a time...won't even have 2 on the bench at the same time so I don't have an old fart brain freeze and get any critical components bass akwards…..too easy to make simple dumb mistakes.

I will post an update when I am straightened out

Thanks again

I am sure I noted the wrong length down for my MONSTER bolt

[VASCAR2]

One thing I failed to mention is how accurate are our calipers. I suspect my calipers are good to within .002 maybe a little less accurate (or how repeatable). You throw in all the variables and you see how tolerances can stack and create issues. It just bugs me a manufacturer would continue to manufacture a 2.800 inch long 6.5 Grendel bolt.

Odin Works was the first to experience pierced primers which was traced to excessive FP penetration and 2.800 length bolts. The first Toolcraft 6.5 Grendel bolts were 2.800 but they quickly changed to 2.8100 length. There were one or two other companies that had an initial run of 2.800 length 6.5 Grendel bolts but switched to 2.810 length bolts.

Like I mentioned in my previous post. Your Brownell’s BCG is very close and the only way I’d know for sure is to check the protrusion with a gauge. When I figured your BCG might be .002 long I was using the figure of 3.279 for firing pin length. The specification for FP length is vague but lets say spec is 3.279 +or- .001. A FP length of 3.280 like one of mine might pass. To many variables in the thousandths of an inch to know for sure.

In all my research most sources indicate AR-15 firing pin length is 3.279. One source listed FP length of 3.279 with a tolerance of -.009. Other sources listed different FP lengths + or - .001. Most sources refer to bolt length, bolt face depth and FP protrusion more than FP length. There doesn’t appear to be an accepted manufacturing tolerance for bolt FP as long as protrusion is in spec. With mass produced products it kind of makes sense to use the FP protrusion to account for variations in the manufacturing process.

[drykilned]

I bought and installed a Brownells 6.5 Grendel Type II BCG last year and installed in my BCA Barreled Anderson upper. Had multiple failure to lock into battery causing jams requiring one to mortar the BCG in order to correct the jam. Did that only with mag in place and chambering a round from the mag. Worked fine single loading through chamber by hand. I returned the BCG to Brownells and bought another BCA bcg for almost half the cost of the Brownells. Worked just fine. Have built two 18" SS BCA barreled uppers, both now with Anderson receivers and lowers. one with velocity 3# trigger and one with CMMG premium lower parts kit and trigger. Long story short, BCA bcg works, Brownells did not.

[Chance-dg]

I was on the phone with Brownells tech support for about 20 minutes and they assured me this bolt would be fine even though the bolt length (tail is short) the FP has been shortened to accommodate the bolt length. If I return it the reimbursement would be a gift card for Brownells
Option 0: Pay $225.00 plus shipping to Wilson Combat for their Grendel type 2 BCG to match my WC barrel
Option 1: Pay more for a Faxon BCG
Option 2: Pay more for an Odin works BCG
Option 3: Use the Brownells BCG and hope it doesn't malfunction
Option 4: Get a Monster bolt and FP from SixFiveArms and use the Brownells carrier
Option 5: Take the gift card (and use for something else above) and spend additional cash for an Alexander Arms BCG or another from another source
Tool Craft etc>

what would the HOARD do???

[BCHunter]

Just run it,...brownell sources these products from various manufacturers. Most likely a Toolcraft.
If it doesn't work for some reason, you can return it and pursue other options.

Of your options
#2 Odins works are short same as your brownells
#4 option is just the bolt you have to buy a standard firing pin, from another source,...usually people buy a 5.56 bcg. Switch out the bolt with the monster bolt and reuse the firing pin.

Check other sites for prices on bcg. Joe bob outfitters, armor alley, palmetto state arms, should have bcg around 100.00ish

[Chance-dg]

I took option 4 on my last build Group Buy 16" Monster barrel and bolt and used a BCM 5.56 BCG and just swapped out the bolt and it runs great

Thanks

[VASCAR2]

As long as you know Brownell’s uses a shorter bolt and requires a shorter firing pin I think you can safely test the BCG. If the firing pin protrusion is on the edge of being in spec you might not experience any issue but I wouldn’t use standard small rifle primers with thinner cups. I use CCI 450 or CCI 41 primers (thicker primer cups) in my AR-15’s just to be on the safe side.

I have three Monster bolts IIRC and they are very good bolts. I’d have no hesitation using the Brownell’s bolt carrier and a Monster bolt with milspec firing pin.

[Chance-dg]

Good call Vascar2...….I have only 1 case of cci 400 (1000) I will sell and switch to 450s I already gota hold of John and am getting another MONSTER bolt and mil spec FP...…..will package up this Brownells bolt and firing pin and mark them well......back bottom of one of the safes

thanks

[Chance-dg]

I only have $94.00 in the Brownells BCG...I have a vendors account with them and caught it on sale before xmas…..so with the MONSTER bolt and a FP say $70.00 for both and shipping really a little less than I have in my Bravo Co BCG and other MONSTER bolt.

Really a great learning experience here $165.00 plus all the gained knowledge.....Hope this helps someone else that comes to the forum!!

[Chance-dg]

I have a good assortment of carriers from AP, BCM and a lower end one from Ruger in my other rifles and carbines.....the Sig is out as it is a piston drive.

[Lastrites]

My fairly recent ToolCraft works well, correct spec's and a bargain at $79.

[Chance-dg]

that's good.....was it 6.5 G when you got it or did you add a Monster bolt in it??

[FLshooter]

I have purchased several PSA Toolcraft bolts and complete BCG.I find them to be great quality and the price is good.$72 for a bolt,hundred dollars for the complete BCG.