mangled bullets

[Schaut]

I acquired my grendel from a private party. It is my first ar platform rifle. The previous owner had included some of his hand loads so I stopped at a friends on the way home to see how it would shoot at 100yds. The first group was just over an inch and it went downhill from there. Couldn't figure what the issue was. I checked the ground connector link with my friend's ar in .223 and grouped well under an inch. So started considering what could be wrong with the rifle. I had an armorer re torque the barrel nut and give the rifle a general going over and it checked out okay. I shot some of my own loads through it and now the groups were consistant but far from the tight grouping I have heard about. Still struggling to get close to an inch. I believe I had posted before about scratches and gouging to the brass and that the lugs on the bolt might be the problem. I modified those and the extractor and also found the mags were leaving a long scratch on the case so that was fixed. I finally ran a dummy round through a cycle and noticed severe scratching on the bullet. Apparently caused by the barrel extension lugs as the round goes up the feed ramp and into the chamber. I can't be positive this is causing the lack of tight grouping but it can't be helping. My next move will be to take off the barrel to access the barrel extension lugs and smooth out the parts of the lugs that are contacting the bullet. Also the lugs at 2 and 3 o'clock that are probably responsible for casing marks during extraction. Anyone else had similar issues?

[seatleroadwr]

Try your rife single shot to see if that helps your accuracy. I have had the problem you described. I glued a strip of 400 grit sand paper to the end of a 12 inch 1/4 " dowel rod and chucked it up in the drill. With this I was able to polish the feed ramps without removing the barrel from the receiver.

[ducks-and-bucks]

Some may not agree but in my experiance with my grendel it is a finiky round. Lots of loads will shoot an inch group in it but you gotta find that one sweet spot with barrel harmonics and it will shrink to a one holer. It also depends on what barrel you have... If its a factory barrel I'd only expect half an inch at best. Custom barrels better shoot one hole groups for me... and usually do. I just found my load for my grendel and have shot a few one hole groups at 100 and 200 yards.

[Tedward]

I acquired my grendel from a private party. It is my first ar platform rifle. The previous owner had included some of his hand loads so I stopped at a friends on the way home to see how it would shoot at 100yds. The first group was just over an inch and it went downhill from there. Couldn't figure what the issue was. I checked the ground connector link with my friend's ar in .223 and grouped well under an inch. So started considering what could be wrong with the rifle. I had an armorer re torque the barrel nut and give the rifle a general going over and it checked out okay. I shot some of my own loads through it and now the groups were consistant but far from the tight grouping I have heard about. Still struggling to get close to an inch. I believe I had posted before about scratches and gouging to the brass and that the lugs on the bolt might be the problem. I modified those and the extractor and also found the mags were leaving a long scratch on the case so that was fixed. I finally ran a dummy round through a cycle and noticed severe scratching on the bullet. Apparently caused by the barrel extension lugs as the round goes up the feed ramp and into the chamber. I can't be positive this is causing the lack of tight grouping but it can't be helping. My next move will be to take off the barrel to access the barrel extension lugs and smooth out the parts of the lugs that are contacting the bullet. Also the lugs at 2 and 3 o'clock that are probably responsible for casing marks during extraction. Anyone else had similar issues?

I hate to say it but there might have been a reason it was sold. If it wasn't a friend, don't put to much money into the barrel or send it to a barrel professional to determine if its any good.

You really don't know causing issues like being bent or if it was dropped or fell of a truck by acident. That is an issue of buying someone else's problem. Truthfully if I had a known bad barrel it would become a great horse shoe stake and I wouldn't pass my issue on to someone else to save myself a buck. Just wrong..... You might want to cut your loses or take to a barrel guy.

Good luck

[seatleroadwr]

Another thing you might try is using some jb bore paste in the barrel. I've had a few factory barrels that started life very rough. The first group would be good but the group would deteriorate quickly. My wife's 223 has a AR Stoner barrel that we extreamly rough. I used Tubb's final finish on it and the JB bore paste and the rifle now shoots .5MOA fairly reliably.

[Bike Effects]

As a courtesy to Schaut, I have attached a picture of one of his damaged bullets.

[Schaut]

thanks b.e. Couldn't figure out how to do it directly and didn't want to go through the posting to photobucket or whatever then the url etc.

[Schaut]

I hate to say it but there might have been a reason it was sold. If it wasn't a friend, don't put to much money into the barrel or send it to a barrel professional to determine if its any good.

You really don't know causing issues like being bent or if it was dropped or fell of a truck by acident. That is an issue of buying someone else's problem. Truthfully if I had a known bad barrel it would become a great horse shoe stake and I wouldn't pass my issue on to someone else to save myself a buck. Just wrong..... You might want to cut your loses or take to a barrel guy.

Good luck

Looking down the barrel it looks fine. I don't think it would have done as well as it has if it was damaged. I'll keep ya'll posted.

[jawbone]

first thing i do when i get mags is disassemble them, then take 400 grit followed by 800 grit sandpaper and knock the edges off the inside of the feeder lips.
i'm still trying to figure out, without breaking down the barrel assembly, how to soften the 2 o'clock and 3 o'clock lugs, which are gouging. i know i could maybe take a loop off the extractor spring, but something tells me i'd be better served just softening the edges of 2 and 3 o'clock. anybody have any advice on this?

Bill?

[Bike Effects]

I'm trying to look ahead for my build and after talking to my barrel maker (Kreiger) I purchased my own barrel extension and did some polishing before it is installed on the barrel. I used a Dremel polishing point and went in from the breech end and working at an angle polished the edge of the locking lugs. I let the polishing point run between the two lugs so it could get the corners. Pulling my finger out of the extension reveals less aggressive corners. This is a difficult. Procedure to describe but was not too bad to do. You could do it with the barrel attached but not in the receiver. I won't know for months if this actually worked.