40XB Issue

[BillW73]

I have a 40XB that I got thru the CMP. I primarily use iron sights and can keep all the rounds in the 10ring on standard 22 targets at 50 and 100 yards most of the time. I have found that the barrel like to be clean when I start shooting.
The issue is that out of every ten or 15 rounds it will throw one out into left field. By that I mean as far as 4 or 5 inches out, and it can be in any direction. Does not matter what kind of ammo I am using.
I have not started looking into this yet other that looking at the crown with a magnifying glass but nothing jumps out.
Any ideas as to what I should start looking for in the barrel that would cause this?

 

[68hoyt]

What ammo have you tried ?

 

[buffalowinter]

If it's not an ammo issue, then it is most likely a bedding issue. After it throws the flyer, where do the next shots go...into the flyer for a new group (shift in point of impact), or back into the old group?

 

[BuckeyePrecision]

For such an intermittent issue I would have to agree with buffalowinter, a bedding issue does sound like the most likely culprit. I would take a good look at the crown as well. My old 513T had a little nick in the crown and while I would expect that to cause an issue all of the time, this one was intermittent, I would get a random flier I couldnt explain. At the time I was a broke college kid and couldnt afford to get it fixed (and didint really believe that was the issue) so I used it as is for a few years as is. I finally got it fixed and the issue went away immediately.
I dont know how the 40XB's are but a lot of the old target rifles did not have any recess to the crown, so they were pretty easy to damage.

 

[leliason]

My xb has been recrowned, that being said my barrel likes to be warm. The cold bore on my xb is awful. Its an absolute tac driver once a few shots have been taken. It is a must to shoot sighters or fowling shots to warm up before shooting groups. 2 or 3 shots usually does it. Hope that is helpful.

 

[Tim7139]

Something that wild is likely not bedding.
two candidates. What type and how old is ammo?
Do you know how to properly disassemble the bolt? If so get it apart and properly clean everything. Reassemble with zero grease of any kind, a bit of very light oil on the pin is OK, if you can see it, it’s too much.
Last thing is replace the FP spring with a proper one, it could be that and it isa cheap fix.
I’d bet it’s crap ammo or inconsistent ignition .

 

[1badDart]

I have a 40XB that I got thru the CMP. I primarily use iron sights and can keep all the rounds in the 10ring on standard 22 targets at 50 and 100 yards most of the time. I have found that the barrel like to be clean when I start shooting.
The issue is that out of every ten or 15 rounds it will throw one out into left field. By that I mean as far as 4 or 5 inches out, and it can be in any direction. Does not matter what kind of ammo I am using.
I have not started looking into this yet other that looking at the crown with a magnifying glass but nothing jumps out.
Any ideas as to what I should start looking for in the barrel that would cause this?

Are you using the tuners in the stock? I tried a bunch of different settings on mine and it was inconsistent. It would shoot well one time and the next it would be wild. I wound up placing a piece of inner tube between the barrel and stock to make it shoot consistently well.

 

[BillW73]

Thanks for the replies.
As far as ammo, makes no difference. I shoot Eley Match and Tenex to Blazer and Golden Bullet when I am plinking. They all do it. The rounds after the flyer go right back to point of aim.
I have lived with this ever since I got the rifle from the CMP in the early 2000's. Just now have a itch to do something about it. As this was a Army rifle at one time, who knows what kind of life it had.
Have a friend with a bore scope, and a bedding issue never crossed my mind, so I will look into that. I have also never taken the bolt apart to give a good cleaning, will try that also.

 

[flatland1]

I had two of the CMP 40XB rifles, but only shot one of them from prone, with a cheap Weaver KT15 scope on it. Those suckers are so heavy compared to my old Anschutz 1611...even when shooting on a padded mat on bare ground, my left (support) elbow would get a little 'tired' after shooting 50rds with that truck-axle bbl. But, it was so steady in prone that on a day with good sunlight, I could see nearly every bullet arcing down into the target through the scope while shooting from 100yds with it. I'd borescoped both these barrels, and though they'd both been shoot enough to have that 'blasted' appearance on the lower 1/3 of the bore, they both shot pretty decently. I traded the one I shot prone to a good friend who wanted it for getting his kids started shooting, and pulled the other one apart to have jelrod do the V-22 magazine repeater conversion on it. I did two barrels for it - a Lilja titebore & Krieger sendero, both chambered with my EPS reamer, and they're both excellent shooters on that action, which I've got pillared & Marine Tex bedded in a Manners Elite T4A. I've never needed to do anything to the bolt other than to strip & clean, then re-lube it lightly with low viscosity oil, but since I pillared & bedded it in the Manners stock, it's been as accurate as my V-22 repeaters, just not quite as smooth as they are.