Grendel Bolt Issues, Won't Full Battery ; Toolcraft, Radical Firearms, KM Tactical

[RedZero]

I have three new grendel builds that have run into trouble. All three are type2, two of them being Grendel calibers and one being Beowulf 50cal that uses a grendel type2 bolt. I bought two of the bolts and the third was included with a parts purchase. I noticed that i wasn't able to go full battery and after going through the firearms multiple times i finally determined it was bolt issues.

Tool Craft
0.136 = Bolt Face Depth
2.802 = Bolt Length
0.273 = Lug Length
3.266 = Fireing Pin (SHORTER FIRING PIN)

Radical Firearms
0.136 = Bolt Face Depth
2.800 = Bolt Length
0.279 = Lug Length
3.277 = Fireing Pin

KM Tactical
0.124 = Bolt Face Depth
2.797 = Bolt Length
0.273 = Lug Length
3.277 = Fireing Pin

Tool Craft does chamber a round in all three firearms thankfully, but it is the shorter fireing pin design. I bought this late 2019 early 2020 from Optics Planet so don't think these bolts are not still around becouse THEY ARE.

Radical Firearms bolt will not chamber a round in any of the three firearms. The only diffrences are the fireing pin and the lug length. I haven't been able to find the accurate lug length spec on the grendel bolt to know that this is indeed out of spec or if my others are. Fireing pin protrusion IS too much. ????

KM Tactical bolt, they apparently sent me a type1 i guess. Bolt Face Depth is 0.124 which won't work in a type2 barrel extension. ???? at their attention to detail and quality control but i should have expected as much from them.

From what I read on the forums here, the Alexander Arms Grendel bolts work really well? Im asking becouse I'd hate to buy a couple and still have more issues. Its bad enough that I've lost all faith in the these three rifle,s and now gonna have to fork out a $350 dollars for headspace gauges for reassurance in the two calibers.

Anyone able to possibly messure the Alexander Arms grendel type2 bolt lug length for me? Im just curious.

[VASCAR2]

[RedZero]

@vascar2 Thanks, good additional information there. Ill also check out the monster bolts, much appreciated. The KM Tactical bolt came with some Beowulf parts I purchased. Some stuff is hard to find right now which has forced me to buy from places i wouldn't normally deal with. Desperate times and what not.

[VASCAR2]

It is amazing how the supply of firearms and ammunition had started to level out and prices were starting to moderate. Overnight between Covid-19 and the riots firearms and ammunition inventory has been sold out. Fortunately I have a decent stock pile of reloading components and ammunition. I was working on another pistol build but decided to wait till the panic subsides to finish it.

This reminds of 2008 and 2012 elections where there was a run on firearms, ammunition and related products. Hopefully you can get your builds on track. Any time you step away from 5.56/223 in the AR-15 there is more potential for issues. Not as much commonality or knowledge base. Not insurmountable but just something you have to be aware and try to resolve, usually on your own.

[MSRAddict]

Now you have me wondering...

I started measuring my 6.5 Grendel upper BCG parts. I am also seeing variations in bolt and firing pin length. I have one 16 IN barrel carbine working and one 12 IN PSA barrel/BCG with issues. My original bolt from PSA had the extractor body sticking way far out from the bolt body. Bad extractor or bad pivot hole, not investigated yet. Using a different bolt, I am still seeing failures to lock up the bolt on second round and once I got lockup but had to tap the BCG back out of lockup with a live round in the chamber. I have a new Monster bolt that I will try next. I probably have two useless bolts. Yay me.

[VASCAR2]

[MSRAddict]

Thanks for the great ideas. It sounds like you suspect the bolt may not be going back far enough after firing to give it the spring energy it needs to fully chamber the next round. I will check this out, as well as your other excellent suggestions.

[Kswhitetails]

I'm confused. Let me get this straight - You have three Grendel bolt uppers, a 16" carbine, a 12" PSA pistol, and a Beowulf. None of your bolts will reliably chamber a round or rounds under fire, have I got that correct?

Your Radical is trash. Bolt lug too long, that explains that one. Get ahold of them and see what they'll do for you.
Your Toolcraft looks as though it just need a longer firing pin, if I've read that right. Use the pin from your Radical bolt?
KM Tac should be on top of replacing your type one bolt without delay.

IMO - Headspace gauges are unnecessary; Measure the shoulder on an unfired factory round or brass, then fire your first round from the hip and take measurements again on that fired piece of brass. That will give you your growth number, from which you can determine chamber length to shoulder. This isn't a 70Kpsi precision magnum chamber; go/no-go gauges don't mean in gas guns what they do in bolts. Assuming caliber is correct: It either chambers (chamber is long enough) or it won't (chamber isn't long enough). AR chambers are somewhat sloppy to begin with - to assist in the auto-loading extraction cycle.

The AA bolts are gtg. As are the group buy from sixfivearms. I'd do the group buy first, unless you can't wait a few more days, they're as good and cheaper.

It seems like you're the victim of tolerance stacking and QC failures...

[MSRAddict]

Just had another try at the rande.

Sorry it took me so long to report. I opened the gas block 1/4 turn and changed out the bolt for my new Monster from SixFiveArms. Everything works like it is supposed to. I might back the gas down a little and see what happens next time. I am done buying anything but Monster Bolts from SixFiveArms. Those guys rock! Thanks for the help, everyone.

[VASCAR2]

Thanks for the update, glad you got it running!