Grendelhunter.com - Complete 6.5 Grendel Upper

[Aged1]

Any update on how it shoots??

Shooting summary on mine (22" fluted stainless, rifle gas, 1-8 twist, 16.5 key mod hand guard, and bolt/bcg) drum roll, ONE HOLE. And that's brand new bbl. the hole could get smaller with more practice.
Other parts of that story..100 grain Sierra varmiter with 27.5 gr of Leverevolution, not magnum primers (trying but local sources are OUT). I have varied the powder charge +|- a grain...drats...still one hole. The. Shot some Hornady 123 gun eld, and still one hole.
PLUS I have send Grendelhunter a few emails and the response is always timely, and helpful. With the last exchange he offered a unsolicited " gift". I'll keep specifics to myself to spare him unneeded requests. But even without the "gift/special treatment" I give Grendelhunter high marks. An AR expert I am not, but one hole groups make that meaningless.

[dgunnut]

I was able to get it out to the range this weekend and put 30 rounds through it. Overall, it shot well. 4 of my 8 groups were 1" or under. A few groups that were larger were likely caused by my cleaning the barrel in between to properly break it in. And/or they could have been shooter error.

Over time I will be getting other ammo to try and getting dies so I can reload for it. I'll keep you guys posted on it as I do more.

Here is a link to the video on the first 30 rounds:

https://youtu.be/CAj3Jy21pZc

-dgunnut

So, since I posted my initial results I've been back to the range two more times. Unfortunately, something must have changed, because I struggled to shoot anything close to an inch, where before I had several groups under 1".

I have shot more of the Hornady SST (although a different lot than before), Hornady Black, and Hornady A-max. The majority of groups are now 2-3"! I first tried taking off the scope and re-attaching it, with no major improvement. The last trip I shot some handloads using 107 SMK's and IMR 8208XBR at various charge levels and the best grouping I got was close to an 1", with the rest all 2" or more.

I'm baffled by why first indications showed this to be a fairly accurate upper, but now 100 rounds later I struggle to get anything decent accuracy wise. The only thing I can think of that I changed was applying loctite to the barrel thread protector to keep it from coming loose. I can't imagine this would have an effect on accuracy...

I am planning on putting out a video in a few days with more info and showing some of the targets. I would like to think it's not the shooter, especially since during my last range trip I took along my new Savage FV12 in .22-250 and shot decent with that.

I am looking for any ideas you guys may have on things to check.

-dgunnut

[brassbrite]

Triple check every bolt, nut, barrel nut, scope mount, etc etc....

I was looking over my guns the other night and discovered that I had several scope mounts that came loose after the last outing at the range. I am always meticulous about keeping everything tight.

I guess when you shoot the head transfer can cause things to swell and contract with heating up and then cooling causing loose components. I cant say for sure that this is what is happening but I always seem to have to re-tighten things after a few trips to the range. Then they settle in and are fine.

Also make sure you break in your new barrel correctly. That will help with long term accuracy.

Interested to find out what the problem was. Let us know what you found out please.

[brassbrite]

^heat transfer

[brassbrite]

I just ordered a 20in barrel and bolt yesterday. So I am kind of interested in knowing whats going on.

[Lastrites]

I just had the opportunity to quickly look over a co-employee's 16" Grendelhunter upper he just received, the one that was on the close out sale. I noticed right off on this upper that the gas block appears slightly canted, coupled with the barrel possibly not being centered in the Strike Industry rail as it appeared to my eye. Also on that rail it uses 4 set screws to either lock the rail to the receiver or they assist in timing the rail square to the upper, doesn't appear have any lock-tite on the screws which I felt was odd as I certainly would have used it on those screws.

Bwtn the gb being possibly canted and likely the rail needing adjustment I am certain my future holds a tear down and reassembly of his upper. But I suggested to him to simply give it a complete cleaning, toss a scope and some irons on it and boresight it and we are going to run some ammo through it at the office.

Dgunnut, besides checking the obvious of loose screw/nuts and although you've only shot 100 rounds or so, do you think it's possibly you've had a build up of copper in the barrel? While a copper build up is a stretch with such a low round count, it's something to consider.

[dgunnut]

Triple check every bolt, nut, barrel nut, scope mount, etc etc....

I was looking over my guns the other night and discovered that I had several scope mounts that came loose after the last outing at the range. I am always meticulous about keeping everything tight.

I guess when you shoot the head transfer can cause things to swell and contract with heating up and then cooling causing loose components. I cant say for sure that this is what is happening but I always seem to have to re-tighten things after a few trips to the range. Then they settle in and are fine.

Also make sure you break in your new barrel correctly. That will help with long term accuracy.

Interested to find out what the problem was. Let us know what you found out please.

Good thoughts. I was planning to check all fasteners next, but need to go through it.

I laughed out loud when you mentioned "make sure you break in your new barrel correctly". I've seen advice on this topic ranging from clean after every shot for the first 100 using light grade sand paper (joking a bit of course) to never clean it...ever

I mentioned cleaning it every 5 rounds during the first 20 and people jumped all over me that I shouldn't clean it.

Definitely open to hearing what your opinion is on the topic and if anyone has hard data that shows how to break in a barrel "properly"

[dgunnut]

I just had the opportunity to quickly look over a co-employee's 16" Grendelhunter upper he just received, the one that was on the close out sale. I noticed right off on this upper that the gas block appears slightly canted, coupled with the barrel possibly not being centered in the Strike Industry rail as it appeared to my eye. Also on that rail it uses 4 set screws to either lock the rail to the receiver or they assist in timing the rail square to the upper, doesn't appear have any lock-tite on the screws which I felt was odd as I certainly would have used it on those screws.

Bwtn the gb being possibly canted and likely the rail needing adjustment I am certain my future holds a tear down and reassembly of his upper. But I suggested to him to simply give it a complete cleaning, toss a scope and some irons on it and boresight it and we are going to run some ammo through it at the office.

Dgunnut, besides checking the obvious of loose screw/nuts and although you've only shot 100 rounds or so, do you think it's possibly you've had a build up of copper in the barrel? While a copper build up is a stretch with such a low round count, it's something to consider.

Mine was also on the close out sale awhile back. I will take a closer look at it to see if the rail is not aligned or gas block is canted.

I thoroughly cleaned it between the first and second trip. Don't recall if I used a copper solvent or not. Then I cleaned just the barrel between the 2nd and 3rd range trips. I specifically used a copper solvent at that time. Similar results during both 2nd and 3rd range trip.

I'm looking at swapping the scope back to another upper shooting that upper to make sure the scope and mount combo is Ok. I have the scope in a Burris PEPPR mount with the quick detach features. I haven't had an issue with the scope and mount before, but who knows...

[mdewitt71]

Any new info or reviews?
Looking at the Grendel Hunter 18" SS upper.......

[Crusty]

Dez Arms' recommended break in procedure

[Crusty]

[Armadillo66]

I wish Grendel Hunter had target crown barrels in other lengths than 16" Although I really like that upper for the price so I may settle for 16" if I order one from them

[doofus65]

Would this also affect the ability to extract?
I had a stove pipe when out hunting last fall and I checked the front block and I see some soot.

[Crusty]

Look for the Johnny's Reloading Bench Youtube video about Grendel extractors. There's a significant number of Grendel extractors out there which lock up cases in the rim groove as they exit the bolt. His fix is valid and it worked for me.

Stronger extractor springs and o-rings cause excessive extractor force which shaves brass off your cases and the shavings are left on the bolt face to cause other problems.

Stovepipes can be caused by the action cycling too fast (though a grabby extractor can do it too).

Regardless, the soot indicates pressure leakage that will not be conducive to the most consistent groups. I use blue Loctite to seal my gas blocks and tubes, and when I get around to it I'll buy some high temperature blue LT for that purpose. I also have a short length of vacuum hose that I push onto the end of my gas tube afterwards and blow through it to make certain that I didn't block off the gas channel with LT.

[rmiller107]

working on coordinating a group buy for a complete upper if folks are interested

http://www.65grendel.com/forum/showthread.php?16038-Interest-in-Complete-Upper-Group-Buy