Few questions on barrel selection

[alpha0815]

[Blackops_1]

I'm researching building a Grendel and was told go with a longer gas system if you go 18". You can do ILGS or RLGS. Rifle is the most common so that's what I'll use since most data will support it. Both X-Caliber and Criterion are great manuf's. I was recommended X-Caliber or PF, so really no bad choices here. These are all some of the top tier options.

Btw I'm curious why you picked a JP bolt since your not looking at their barrels? Does JP not make an 18' you like? Considering that bolts and barrels are made to a certain tolerance level at a price point. It is logical that the barrel and bolt being matched together by the same manuf. will reduce tolerance stacking. But I'm no expert so I'll be following along, my .02.

[grayfox]

Several threads on here that discuss this; upshot IIRC is that for 18" especially suppressed, the RLGS is the way to go.

[Rosecrans1]

Make sure the JP bolt is a Grendel II bolt. Most barrels are Grendel II. JP Products may not be. IMHO, it's best to buy the matching bolt with the barrel.

[A5BLASTER]

Make sure the JP bolt is a Grendel II bolt. Most barrels are Grendel II. JP Products may not be. IMHO, it's best to buy the matching bolt with the barrel.

The JP bolt is spec'd for a .136 bolt face depth. That is the depth used for the sammi grendel chamber when headspacing the bolt.

Grendel II is a wildcat abortion chamber and has nothing too do with the bolt face depth.

His JP bolt will properly headspace too any BA, PF, AA,JP,Faxon,Odion,BCA barrel. And if he goes with a custom pipe he can have it headspaced too that bolt face depth as well. X-caliber has that option.

X-caliber will let you send in a bolt with a .136 bolt face depth and charge you 10 bucks to headspace it top a 264lbc chambered barrel if that's what you want.

Grendel II and Type II is not the same thing.

Grendel II is the wildcat chamber.

Type II is a wording used by many vendors too describe that their bolt headspace is set for .136 bolt face depth.

[alpha0815]

So to address the JP bolt comments....yes, of course I've confirmed that the JP bolt is Type II. It's my opinion that JP makes one of the best bolts on the market. The enhancements made to the ejector, extractor, gas rings, and beefed up areas around the critical failure points are all improvement over standard bolt. I'm not new to AR15 and have been building them for years, dozens of them in my collection. I've been all in with 6.8 SPC and 300 BLK over the years and now it's time to stretch the legs and get into the Grendel for the superior ballistics and extended range that it offers.

Why not JP barrel? Because they are fricken expensive....that's why. LOL. Almost $600 for a black teflon coated barrel. The barrel matched to the bolt for headspace can and is a topic that gets overblown IMO. I have headspaced many bolts and barrels from different manufacturers. If you use a reputable manufacturer for either part you are fine 99% of the time. I don't own Grendel go-no-go gauges but a friend of my does and I'll be checking it myself, regardless.

But to some of the concerns, if I go with X-Caliber they will provide a headspaced JP bolt. Same with Criterion...if you order directly from them the offer only a JP headspaced bolt. However, Primary Arms arms has the Criterion barrel for under $300 when on sale or coupon code and no headspaced bolt offered. I'd be on my own there.

Will definitely go RLGS, just looking for experience with X-Caliber and Criterion (non-PF chambered) Grendel feedback as I have not personally used either of those manufacturers in the past.

Thanks!

[Rosecrans1]

Type! Type! Type! Type! It's what I meant but not what was written! But JP sells both bolt face depths and that was my main concern to bring up. Thanks for correcting!

[A5BLASTER]

Type! Type! Type! Type! It's what I meant but not what was written! But JP sells both bolt face depths and that was my main concern to bring up. Thanks for correcting!

No JP does not sell both bolt face depths. The only bolt they sale for the grendel is with the .136 bolt face depth.

[Rosecrans1]

You know........I need to start taking meds before posting. You are correct.
I was thinking JSE. (Who I have dealt with over the past 15+ years).

https://www.jsesurplus.com/65grencompletebolt125andcarrierassembly.aspx

Time to become an observer only.

[A5BLASTER]

You know........I need to start taking meds before posting. You are correct.
I was thinking JSE. (Who I have dealt with over the past 15+ years).

https://www.jsesurplus.com/65grencompletebolt125andcarrierassembly.aspx

Time to become an observer only.

No reason too be an observer only sir. Jump in and mix it up with us.

I just knew about the JP bolt because I had a JP grendel barrel and bolt combo once.