Mossberg MMR Woes - Need Troubleshooting Advice Please

Smesh

Smesh

New member
After over a month on the road, I finally made it back to the range to sight in the replacement Nikon Coyote Special scope that I thought was the problem with my rifle. Unfortunately, my range session was similar this time around.

I bore sighted the rifle at home, then set up a target at 25 yards. It was all over the paper at first, but seemed to settle down a bit, and I had a couple of strings where I could keep three shots into about 3", but that was fleeting, and obviously very poor performance.

Next I tried two 12x12" shoot and see targets stacked one on top of the other at 100 yards. I could not get a group under 8" and most of the time I couldn't stay on paper. I ended up putting three boxes of Hornady Varmint Express ammo with 55 grain V-Max, in the hopes that I just needed to get some lead through it. Previously, I had broken the rifle in with a shoot and clean regimen before initial sight in. I did manage to hit some gongs out to as far as 300 yards, but it seemed like it was hit and miss by very wide margins.

Since this is not the only ammo I've tried, I'm thinking it must be a different issue. I've changed the trigger springs and while there is plenty of creep, I've used proper rests and techniques and I can't for the life of me figure out what could be the problem. Aside from getting the rifle bore-scoped, I'm stumped. Most of my guns are custom bolt guns, and some I tweaked myself, including triggers, pillar bedding, lapping, etc. But when it comes to AR's, I have never really tried to accurize one. Is there something I should be looking for that's a common source of problems with these rifles?

I'm used to tiny groups, and while I didn't expect bolt gun accuracy, there is no way I would take this rifle into the field as is. I might try one of my proven scopes on it first, but if I can't get at least 1.5 MOA, this rifle and scope are both going up for sale.

 
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Mossberg requires me to send the rifle to Texas, then it will go to CT, then back to Texas, then back here, and of course it needs to go through FFL's. They don't have any service centers here in CA. That said, they have not had any real problems with these rifles.

Is it possible that converting it over for the bullet button (done by the dealer) or putting in a trigger spring kit could have caused something to go haywire? Is there anything else I can look for? Any recommended gunsmiths in the Sherman Oaks or general LA area I could take the rifle to for an inspection? The tech mentioned something out misalignment of the barrel as a possible problem.
 
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what scope mount are you using, how was it installed, what is it torqued down to? with how light the recoil is on a 556/223, it doesn't happen often, but it can... some rifles are picky about rest placement, have you tried a bipod or only used a rest? have you tried single feeding?

i have had a [beeep] of a time with my LWRC. I sent it in and they replaced the trigger and buffer assembly and now it seems to shoot like a completely different gun.

alignment is a definite possibility.
 
I'm using the Burris P.E.P.R mount, and while it should be machined out of one solid piece for proper alignment, unless I turned the scope power ring between shots, that should not be a factor. I have torqued the mount and rings down to spec. Double and triple checked. And Nikon was nice enough to swap me out a replacement over the counter at their LA service center, so I don't think it could be two scope problems in a row.

I have an F-Class heavy rest and bunny ear rear bag, and if you look at the video, you'll see my form and tools are not the problem. There is no muzzle jump to speak of, and I was careful not to allow the studs front or rear to contact the bags under recoil.

I did use a Harris BR bi-pod after as well while engaging the steel plates at 200 and further, but that was after I abandoned trying to shoot groups. I have NOT tried single feeding. I did have a couple of FTF that resulted in kinked shoulders but I figured that was due the empty brass failing to enter the brass catcher causing the action to hang up. I didn't actually see the brass miss the catcher (it always ended up in the bag), but I assumed it bounded off the opening and caused a misfeed on the next round. This only happened twice and I did NOT use those rounds for groups. I didn't have any stuck empties, just those two mis-fed live rounds. I'm using 5 round mags.

I don't know much about alignment setups on ARs, but I think first step is to take it to a gunsmith here and get them to look at it. It's going to cost some dough and be a significant hassle to send the gun to Mossberg and will take at least a month to get it back, if not more, so it's worth it to pay a gunsmith to look at it.

I guess I should have picked up a Predator Pursuit, but this was available immediately and was camo, and I couldn't pass it up. That said, I've read a lot of good things about the MMR. Hopefully it's a quick fix.
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Thanks for your
 
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Originally Posted By: SmeshI'm using the Burris P.E.P.R mount, and while it should be machined out of one solid piece for proper alignment, unless I turned the scope power ring between shots, that should not be a factor. I have torqued the mount and rings down to spec.

when the mount was installed, did you press it forward against the recoil lug and then torque it down? My mount is torqued down to 55 in/lbs (AR10, but i do it for everything now). I have seen people have problems by not torquing them down properly and not having pressed them forward against the recoil lug.

the 556/223 has such light recoil, this is not often the issue, but it is an easy fix.

does your fired brass look normal or does it have gouges/dents/signs of gas bypass?
 
Both my MMRs shoot from .450-1" @ 100 depending on my loads. All my handloads are under an inch & I swap uppers weekly on one of them from the .223 to 6x6.8 and don't have that issue. I have after market triggers in them & bipods always attached. I ran them both at 400 yards Sunday and didn't have anything close to what you are seeing w/yours. I have a PEPR QD base on them both also.
 
Yeah 5spd. Your posts are what convinced me to buy one. I've been reading up on it and some people seem to say barrel nut torque could cause issues like I'm having. Barrel heat can cause fliers but I did wait between groups, and I've never seen a barrel react that wildly to heat so I doubt that is a factor. I just don't want to send in the rifle if I can avoid it. Sending from CA is a real PITA and will incur some $$ that might be better spent here on a simple fix. Hoping someone has some wisdom here on what to look for or knows a good gunsmith close by.
 
Is yours the Hunter model without the flash hider? If so, inspect the crown for any dings or damage. Maybe try removing and re-installing the scope mount and check to ensure the scope is secure in the rings.

The one thing I have to disagree with Captninsano is about the recoil on these rifles. While the felt recoil is next to nothing on these rifles the bolt slamming back and forth is hard on scopes. Most scopes are designed to handle the recoil impulse of bolt action guns where the recoil is backwards. With the AR the recoil is backwards and and then forwards. I have already had to replace one scope on my 20" AR that I use for hunting and target shooting. The scope was the Springfield 5.56 with the BDC set up for the 69gr Match king that Federal loaded. I used that same load in my rifle and it eventually destroyed the scope.
I am waiting on my AR-10 to do the same.
 
Well I hadn't thought of the rifle being hard on the scope. I'm familiar with that situation with air rifles, but not AR's. Everything is tight for sure. My first shot this time at 25 yards was slightly high and right. I adjust and had the next two rounds almost cutting the same hole. Then a wild flier several inches high and left, right off the target. Dumbfounded, I repeated the same thing. Two shots more shots into about a .75" group (at 25 yards mind you). Then I went out to 100 yards. From there it was everywhere. Nothing made sense. I'd hit way high and left, adjust down, then way low and off the paper. split the difference and way high and right. Wasn't any point shooting groups that far off zero, but I finally tried that too. Forget it. On a 12" wide by 24" deep target (2 shoot n see targets stacked), I ended up with I think 5 shots that hit the paper.
 
Cap I'll check the brass, and check to see about pushing the base forward onto the lugs. I'm sure I did it, but worth repeating. Torque on the base was 65 pounds/inch according to spec. Rings too but I can't recall. I think 20 pounds/inch.
 
The brass does indeed have some strange markings. Every case has two gouges on the neck and looks to have a lot of residue all the way past the shoulder. I just don't know how abnormal that is for an AR. Being Canadian, I have never owned or loaded for an AR. I've fired them, but for the most part, that was a long time ago and I wasn't picking up brass to inspect it, or worrying about precision accuracy. Oh and it's indeed a hunter model in brush camo.
 
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The brass looks pretty normal to me, the 2 small scratches are just from when it hits the points on the barrel extension on extraction from the chamber. AFA those groups, wow I can't imagine what would make it shoot that poorly besides a bad barrel or bad scope. And it would be weird to get 2 bad scopes in a row, but not out of the realm of possibility. If the crown looks good I would try one more scope, if that doesn't work IMO it's time to tear it down.

One question: when you first mounted the new scope, how far off was it from being zeroed? Most of the time for me when everything on an AR is true it doesn't take much scope adjustment to get it zeroed, if the scope was optically centered (as a new one should be). If it was a long way off that would lead me to believe that the barrel is bent, or otherwise not right. My $.02
 
The marks IMO are from the M4 ramps and nothing to worry about.
The soot is normal from any AR15 Ive seen, all mine are like that after firing, my RRA/Cmmg/dpms/R15 that I had at one time did the same.
Take a cotton dabber and put it in the muzzle around the crown and see if any cotton is pulled from it, if so its got a snag there and a deburring tool will fix that.
It has to be something very simple IMO.
I would do a scope swap before going further as stated.
 
I think its safe to say you have worked through the basic stuff and now you need to decide if its worth money out of your pocket to have a smith look at it or just send it back. I didnt have to go through a ffl when i shipped mine in for service, is that a cali thing?

Do you know someone with another scope base you can try? Do you have a scope alignment kit to verify the base is not messed up? A second bad scope is possible, unlikely, but possible.

The good smiths i consulted in my area wanted 65-150 just to look at it... I decided to just send it in and let the manufacturer sort it out... It sucks to be without the gun, but hopefully they can get it sorted out quickly and get it back to you.

My lwrc had a lot of the same problems. 4 shot group would shoot 2-3 touching and the others 1-5" away. some would group consistently in the 3" range. Others would be all over the place. It was very frustrating. They claimed to replace the trigger and buffer assemblies. When i got it back it took about 15-20 rounds for it to start cycling properly but it seems to be shooting better. Have only been able to shoot at 30yards because of time but i put 8-9 through the same hole.

I hope you get it sorted out. I know it can be frustrating. I put almost 400 rounds through mine before throwing in the towel and sending it in for service. A lot of money in ammo and time on a problem outside my control.
 
Originally Posted By: SmeshI've been reading up on it and some people seem to say barrel nut torque could cause issues like I'm having.

Have you checked this yet? I don't know a TON about AR's, but I play with them quite a bit. Seems like loose barrel nut could be a factor. I could help you tear it apart and check it out, but I'm up in Monterey.
 
Thanks guys. I'll try a bullet proof scope on it before I send it back. I brought some loose scopes back from Canada in my carry on last week, so now I have a bunch to pick from, and mounts too. I really can't see two bad scopes in a row, but I pulled the Nikon Tactical off my .338 right after deer hunting this year and it was functioning fine other than a broken illuminated reticle knob, so I planned to bring it in for repair. That doesn't effect the internals though. I also have a Nightforce NXS with some badger ordinance rings but that's a bit overkill. I miss having a range right outside my back door. Ugh.
 
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