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loose barrel syndrome

S

steve123

Lt. Colonel
Full Member
Minuteman
Mar 16, 2008
9,942
2,799
none of your business
#1
Yep stay away from me I don't want anybody catching what I have. I need to be quarantined or something, LOL.

A couple years ago with one of my AR's I began to have small POI shifts. I thought it was the scope and bought a higher quality one but nope, replaced the rings-nope, worked up a new load-nope. As time passed the POI shifts got even worse. So long story short it turned out that the barrel had come loose from the extension. I actually cracked it loose with my bare hands one day after reading about someone else here on the Hide having the same problem.

Well I started to have a similar problem about 5 months ago with my mainstay tactical bolt rifle but this time the shifts were smaller and sporadic as to when they occurred.

I first noticed there was a problem at the Scorehigh challenge on their first stage. I couldn't hit a 4" flapper at 255Y and ended up hitting the hostage finishing the lowest at -15, ARGHHH. What a way to start a match aye? The next stage a half hour later, which was a paper stage at the same distance, on about the same size target, the first three shots were centered in the middle and I got 80%. The rest of the match I couldn't tell if there were any problems.

All summer I shot matches at the AZPRC and noticed I'd be off .2 mil high on occasion so I'd adjust for it and be able to hit the steel. Still "very" seldom would this happen so I wasn't sure what to do. I even won quite a bit.

The POI shift problem became very apparent at the Utah shootoffs. A obvious .2 mil shift at 1000Y. Then Zero'd a 6 shot stage on day 1 and had no idea where I was hitting. Day 2 on a stage of similar difficulty I got 19 out of 20 hits. Go figure? It was driving me crazy.

I suspected the POI problem was either my HDMR scope or the barrel had loosened up. I've been busy with work so I wasn't able to test the scope.

A couple weeks after I got back I ordered a Brownells barrel vice and Surgeon action wrench(back ordered) which I picked up earlier this week. Having never removed a barrel before I was expecting to put a fair amount of pressure to break it loose. Not so, it broke loose at the slightest bit of pressure, maybe 5 lbs if I were to take a guess. I'm reasonably certain the barely tight barrel was the culprit of the POI shifts.

Interestingly enough this rifle has always grouped well during this whole experience.

Just wanted to share my "loose barrel syndrome" curse in case someone is having POI shifts.
 
#3
Re: loose barrel syndrome

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#6
Re: loose barrel syndrome

I've seen high end custom built rifles have their barrels come loose.

One theory was that the face of the custom action and the face of these precision barrels had been so perfectly machined that they don't "grab" each other when tightened down. Add in changes of temperature, travel, humidity, etc. and the problem can drive a shooter nuts.

One rifle was a custom built .50 BMG and the other was a custom built .338 Edge. Both were excellent in their machining and precision. Both calibers obviously produce a termendous amount of heat when firing.

What I don't know is how the issue was best resolved. Maybe one of the gunsmiths can chime in on this.
 
#7
Re: loose barrel syndrome

that is likely why sako, and others, use something like a glue on the threads - can make it a bitch for barrel removal - which is likely why others do not
 
#8
Re: loose barrel syndrome

Just a though, but why don't actions use a small set screw to lock the barrel in? Ever tried to remove a barrel where the front scope base screw was contacting the barrel? It'd still be easy to remove the barrel, though, so long as you knew the screw was there.
 
#9
Re: loose barrel syndrome

had my service rifle come loose during a leg match Uhhg, couldn't hit crap at 600 and corrections had no effect, the 300 rapid was all over the place, I realized it during the 200 slow fire while setting up, i grabbed the front sight and carry handle and was able to move them, I quickly borrowed a friends rifle and went on, too late, the match was long lost but since retightning the barrel nut it is back to its usual accuracy.
lesson learned, more torque is better than too little.
 
#10
Re: loose barrel syndrome

I blame the HDMR.
grin.gif


I have to say... Never heard that one before.... Glad you found the culprit.

John
 
#11
Re: loose barrel syndrome

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: billyburl2</div><div class="ubbcode-body">That one hasn't happened to me yet...But just about every other possible connector on my rifle has shaken loose at one time or another! </div></div>

Yep, I have too. Mainly bases but rings also. Blue Loctite has been my friend the last couple years.
 
#12
Re: loose barrel syndrome

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ranger1183</div><div class="ubbcode-body">I've seen high end custom built rifles have their barrels come loose.

One theory was that the face of the custom action and the face of these precision barrels had been so perfectly machined that they don't "grab" each other when tightened down. Add in changes of temperature, travel, humidity, etc. and the problem can drive a shooter nuts.

One rifle was a custom built .50 BMG and the other was a custom built .338 Edge. Both were excellent in their machining and precision. Both calibers obviously produce a termendous amount of heat when firing.

What I don't know is how the issue was best resolved. Maybe one of the gunsmiths can chime in on this. </div></div>

Yeah Ranger, I'm not sure how much the barrel was tightened. The barrel is Melonited and the action is bedded in a MAK tube chassis. Maybe a combination of slick barrel and extra vibration, who know???
 
#13
Re: loose barrel syndrome

Hey still could be the HDMR or possibly the nut behind the butt
grin.gif
No fixing the latter but I'll know if the POI shifts have stopped here in the next month or so.

I have it torqued to 80 ftlbs now so hopefully it'll stay put.

I'm looking forward to seeing what new scopes come out for 2013. Might have to sell a couple of those HDMR's.
wink.gif
 
#14
Re: loose barrel syndrome

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: attherange</div><div class="ubbcode-body">had my service rifle come loose during a leg match Uhhg, couldn't hit crap at 600 and corrections had no effect, the 300 rapid was all over the place, I realized it during the 200 slow fire while setting up, i grabbed the front sight and carry handle and was able to move them, I quickly borrowed a friends rifle and went on, too late, the match was long lost but since retightning the barrel nut it is back to its usual accuracy.
lesson learned, more torque is better than too little. </div></div>

Thanks God! Someone with empathy!
 
#15
Re: loose barrel syndrome

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steve123</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: attherange</div><div class="ubbcode-body">had my service rifle come loose during a leg match Uhhg, couldn't hit crap at 600 and corrections had no effect, the 300 rapid was all over the place, I realized it during the 200 slow fire while setting up, i grabbed the front sight and carry handle and was able to move them, I quickly borrowed a friends rifle and went on, too late, the match was long lost but since retightning the barrel nut it is back to its usual accuracy.
lesson learned, more torque is better than too little. </div></div>

Thanks God! Someone with empathy! </div></div>

I feel your pain bro.
 
#16
Re: loose barrel syndrome

+1

It happened to me during a mid-range F-Class match roughly 3-4 years ago. I couldn't hit the side of a barn and scope adjustments made no difference. When I grabbed the barrel to pick up the rifle, the barrel rotated freely in my hand. grrrrr that relay was a complete waste of ammo and time.

Jeffvn
 
#17
Re: loose barrel syndrome

Somewhat scary isn't it. In the past year I've seen 3 guns that popped loose as soon as a barrel wrench was inserted.
I think some muzzle brakes were indexed off the action-chamber tightness.
Never had one rotate in my hand though, that would be a little much.

OP steve, I did have a barrel on a AR come loose, found out about it when a live round got wedged in above the bolt.
Locked shit up tighter than hell, we had to cut the case out, pliers and screwdriver.
Sent the gun off to get refinished, armorer let us know about loose barrel.
 
#21
Re: loose barrel syndrome

My buddy won a gift certificate at a local gun shop and ended up getting a shitty AR (he's a relative newb to the AR scene). I loaned him a magpul BUIS and he attempted to zero it himself. He reported back that it was all the way to the right and could not get it zeroed. I assumed that the gas block was crooked or some other issue.

I went to the range with him and watched him fire about 10 rounds with results of 4-6moa @ 100 yards - not good enough to zero with. I took the rifle and within 3 rounds I could tell that something was wrong. I put some torque on the FSB and it moved back and forth, but it was solid on the barrel. My next thought was poor fit between the upper and lower, but that was solid. Once I held onto the upper and torqued the barrel I could see that it was completely loose.

He ended up selling that rifle and I found him an LMT MRP which of course is rock solid.
 
#22
Re: loose barrel syndrome

I had a similar issue with an AR , thought the float tube as loose, or the barrel nut. Nope. The barrel unscrewed from the extension by hand. Everything else was tight. Re torqued the extension with liberal red loc tite applied, and tapped the alignment pin into the threads, problem solved. One of my most Accurate uppers now. You never know what can go wrong.
 
#24
Re: loose barrel syndrome

Some AR barrel manufacturers only loctite the extension to the barrel. Melonite heat will destroy the lock. Yours was likely treated with the extension attached. It is pretty sorry to sell barrels without any torque. This is what happened to my LR308.
 
#25
Re: loose barrel syndrome

Wait... This was on your bolt gun correct?

With everybody chiming in about their AR's has me a little confused! lol

On the bolt gun, I'd have that bitch re-torqued to spec, and if it happened to do the same thing, I'd have the action and barrel MPI inspected, and if that yielded nothing... I'd have the threads re-cut.
 
#27
Re: loose barrel syndrome

Not all manufacturers will cut into the threads on a AR barrel after torquing the barrel extension. by drilling through the index pin hole into the threads, the index pin will lock into the threads when pressed in.....I feel this is especially important on Melonited barrels.

My thinking for a bolt gun would be to use a opposite threading direction on the receiver then the direction of twist. That way the twisting force when firing would actually help keep the barrel tight in the action.......
 
#29
Re: loose barrel syndrome


Never had an issue with a bolt gun but have heard of it with AR's...none were pinned or had locktite on them.

Set-screw or red loctite will solve the problem.
 
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