Troubleshooting Help for Finicky Barrel and Unexplained Flier

[diggler1833]

Gents, I am at a loss here. My final answer to this problem is that I just ordered a Brux barrel, and will get it chambered in 6.5x47 and spun on by Matt Stewart of Stewart Rifles.

However, that doesn't guarantee that my problem will go away, so I'm reaching out to see if anyone else (I'm sure) has encountered this problem, and what it eventually turned out to be.

Background: I have an FN SPR A1 that I bought in "as new" condition from a police supply place in FL. I have bedded the action and adjusted the trigger to 2-1/2lbs.

Accuracy: This rifle is not the tack driver that other people report (I have three FN SPRs myself). It will at least throw "normal" groups in the 1.5 MOA range, but in search of acceptable accuracy I've noticed an extremely wierd phenomenon...I have never, ever shot an otherwise good group that didn't contain a wild flier...like 1/2 - 1 mil off. At this point I have at least 7-8, (5) shot groups that have four rounds in a half inch or less...and one that is 2-3" out of the group...and never in the same direction. The other wild part is that this rifle just flat out shotgun patterns with any load that is even the slightest bit into the medium-range of charge weights.

Example: with 168gr Nosler Custom Competitions, over IMR-4064 in Federal brass, I have a node from 42.1 - 42.8gr where I get the 4+1 fliers. From 43.0 - 43.5 it just shoots 1.5 MOA. From 43.5 - 44.5 we're talking progressively opening up to 3 MOA. I've used 168gr and 175gr SMK as well, and Varget powder too. Same results.

Troubleshooting: 1) ammo: I tried my 168gr handloads for this SPR in one of my others, and shot all five shots into a .7 MOA group at 170 yards the other day. I then put five rounds of 175gr factory FGMM into my bad SPR and got another 4+1 group with a shot 3" out at the same distance. I repeated this process again the next day with a 168gr Hornady AMAX handload, but the bad SPR printed a 5-1/4" SHOTGUN PATTERN. I did it a third time with a proven load in one of my other SPRs, and got the same result for the third time. I've reloaded tens of thousands of rounds for many rifles over the last few decades, and while nobody is immune to a stupid moment...I think we can rule out my handloads at this point. I'm literally using the same components from the same tray, box and jug.

2) skill: I'm no Eric Cortina or whoever is the bad-ass marksmanship dude in your mind. However I have a decent background in marksmanship myself. This is an area where people often refuse to believe that they could be the problem. I still throw fliers, but that is a 2-3% of the time deal, not a 20% of the time problem. Let's just say that I have several rifles that are reliable 1/2 MOA or better.

3) Addressing the shot: I have this accuracy problem with the rifle shot off a rest, or a bipod. It makes no difference here. Bench or prone - no difference either.

4) Optics: I was using a Burris XTR II, which was on another rifle for a while and never gave me issues. I checked all screws twice, and nothing was loose (I use blue Loctite).

5) Bedding: I've bedded a dozen rifles or so in my life, and while I'm no amazing gunsmith I've never had a problem yet. When I pulled this rifle apart the bedding looked fine as in nothing had chipped etc... For being a McMillan stock, this A3 is the roughest I've ever seen in the action inlet (I've owned 4 not including the factory FN rifles). The barrel actually sits a few thousandths off in the channel, but is still fully free floated. It was one if the reasons why I bedded the action.

6) Crown: I swabbed the crown of the barrel with a q-tip and nothing caught.

***

So that leaves me with guessing if I have a problem with the barrel (which is my guess), or potentially somewhere else that I can't think of (firing pin spring?).

The fact that this rifle turns into a Mosin Nagant the moment you get halfway up the charge weight is enough for me to rebarrel, but I'm sitting here wondering if I've overlooked something common that is going to turn this into another headache once I get the new tube screwed on.

I know that there were a few years where the chrome was coming off inside the barrel, but this rifle is a USRAC, New Haven gun and an FN 103xx serial. I think this was before the issues, and I've certainly never seen anything wierd coming off on the patches.

I really need to buy a borescope.

Sorry for the length, but I don't want to waste anyone's time on a suggestion that I might have already addressed.

So what do the experts think is going on here?

 

[bbhank]

Every gun/barrel is different and you need to work each one up accordingly. Also if you got a Factory rifle to shoot a .7 MOA Group why is that not good enough?

 

[FisherT&C]

This problem can be created by a reverse taper in the bore; which means a bore gets slightly larger towards the muzzle. A bore should either be a consistent diameter for the entire length or get slightly smaller towards the muzzle. I check every barrel I chamber for a "reverse taper" before it goes in the lathe. When I find a reverse taper I either cut the large portion off if it is very short, about every barrel blank requires some portion of it to be removed anyway; usually due to the lapping process. If cutting the blank down is not an option I send it back to be re-lapped or replaced.

The other cause could be heat which brings out stress relief issues. Stress relief issues could be fixed by cryogenic treating the barrel; there are a few places that do it and it's cheaper than replacing the barrel. However; if there is a reverse taper cryo will not solve the problem.

 

[dimar1492]

Every gun/barrel is different and you need to work each one up accordingly. Also if you got a Factory rifle to shoot a .7 MOA Group why is that not good enough?

I think it was a different rifle that shot that group. I think he was trying to say that the ammo he was using shot a .7 MOA group in a different SPR.

 

[diggler1833]

Every gun/barrel is different and you need to work each one up accordingly. Also if you got a Factory rifle to shoot a .7 MOA Group why is that not good enough?

Yep...the .7 MOA group was a different FN SPR of mine...same load as the one that throws random fliers.

That second FN is a laser. First ever hunting handload produced a .419" group for five shots @ 100. Fastest load development ever.

I just wanted to try that batch of ammo on another rifle to rule out the possibility of some sort of screw-up that I might have introduced in my process. I ended up doing that three times with three bullets and two powders just in case.

If a .308 won't group with 168 or 175 SMKs (or Nosler CC) with Varget or IMR-4064...then there is usually an issue with the gun.

 

[diggler1833]

This problem can be created by a reverse taper in the bore; which means a bore gets slightly larger towards the muzzle. A bore should either be a consistent diameter for the entire length or get slightly smaller towards the muzzle. I check every barrel I chamber for a "reverse taper" before it goes in the lathe. When I find a reverse taper I either cut the large portion off if it is very short, about every barrel blank requires some portion of it to be removed anyway; usually due to the lapping process. If cutting the blank down is not an option I send it back to be re-lapped or replaced.

The other cause could be heat which brings out stress relief issues. Stress relief issues could be fixed by cryogenic treating the barrel; there are a few places that do it and it's cheaper than replacing the barrel. However; if there is a reverse taper cryo will not solve the problem.

I think you're probably onto something. I have no way to test to see if my bore is correctly dimensioned though. I am an amateur at best, even though I have a decent amount if experience monkeying with guns.

My final solution was to order a new barrel. However the fact that I couldn't identify the problem is bugging me.

Regarding heat, I almost never let a rifle get so hot that I can't hold it by the barrel. Certainly in my last tests I fired a total of 5-6 rounds and that was it. Strangely, I did not have much - if any - cold bore shift. I definitely agree though that heat exacerbates stress points.

Thanks for the insight.

 

[ShtrRdy]

Is the flyer in the same general direction from the rest of the group? Is it the same shot fired i.e. shot #5 of a 5-shot group?

If I understand correctly most of the shots in the group have the same POI from one group to a different group?

 

[acudaowner]

don't talk your self into shooting bad before you even get the chance to fire the gun just have fun with it .

 

[CBDR]

don't talk your self into shooting bad before you even get the chance to fire the gun just have fun with it .

10-4, Whatever you think is going to happen will. Positive or negative.

 

[diggler1833]

Is the flyer in the same general direction from the rest of the group? Is it the same shot fired i.e. shot #5 of a 5-shot group?

If I understand correctly most of the shots in the group have the same POI from one group to a different group?

No, the flier can be any shot out of the five, and can be in any direction. I've had it at 7, 4, 11, 3, and 6 o'clock. If it were in the same spot I'd start looking at myself harder, but I don't have this issue with any of my other rifles.

Otherwise the center of the other four shots is the same from group to group. I've taken the best load out to 385 before, and other than the damn flier, the group was right where the ballistic app said it would be.

I chronographed these loads too...no crazy one-off velocities. ES has always been 20-25, and SD in the 10-12 range.

 

[diggler1833]

don't talk your self into shooting bad before you even get the chance to fire the gun just have fun with it .

This one just frustrated me man. I've got (or had as I've rebarreled one already) four .308 bolt guns - three SPRs and an M24R. The other three have never demonstrated this type of issue. Heck, I've got another three .308 semi-autos in the safes too. Call me a caveman who lives in the past, but I love the cartridge.

I put a lot of 168/175gr stuff downrange. I have grown quite fond of the .308s recoil impulse. To me, it's the equivalent of what the .45, 1911 guys talk about.

I still have a couple. 308s that I'm not going to mess with, the M24R for sure. If I flinched and threw fliers everywhere with every rifle then I'd have no further to search for the problem...but I don't. It is a single rifle issue, and I've worn myself out trying to troubleshoot it on an amateur level.

I've got a few thousand 168s and 175s still laying around...looks like I'll have fewer rifles to share them between.

 

[Mike Casselton]

You mentioned checking the scope ring screws.
Did you check the base/rail also?

I'd pull it off and remount it just to eliminate it as a possibility.

I had one come loose a couple years ago and it drove me mad for three range trips.

The top of the receiver looked like this.

Check out the screw on the left.

The was the loosest one and it was actually damaged due to the movement.

I replaced the entire thing with an EGW and haven't had any further issues.

 

[diggler1833]

You mentioned checking the scope ring screws.
Did you check the base/rail also?

I'd pull it off and remount it just to eliminate it as a possibility.

I had one come loose a couple years ago and it drove me mad for three range trips.

The top of the receiver looked like this.
View attachment 7903492

Check out the screw on the left.

View attachment 7903493

The was the loosest one and it was actually damaged due to the movement.

I replaced the entire thing with an EGW and haven't had any further issues.

Yessir, I sure did check the base too. I confirmed it a second time when I pulled everything apart as I have the barreled action ready to take to the 'Smith for the new barrel.

My very first ever venture into "precision rifles" some 20 years ago...I lapped the rings because my wheeler kit showed they were off a bit. Well, I didn't realize how hard it was to get all of the compound off. It resulted in the scope shifting slightly every couple of rounds.

Once I realized my mistake, I bought quality rings and bases, and have not needed to lap them again...but that episode along with a broken Bushnell scope on my first "precision rimfire" conditioned me to look at optics and mounting first when shots go randomly stray.

This current rifle had the Badger base and I was running the "precision matched" Vortex rings. Every screw had a touch of blue Loctite just to help. It isn't a guarantee that a screw won't work loose, but it helps.

It seems like we all need a loose scope to learn the importance of checking it periodically

 

[Pete B]

Stick to 3 shoot groups?

 

[diggler1833]

Stick to 3 shoot groups?

I'll just use the ubiquitous "target quarter" to cover up the stray hole and claim internet greatness.

 

[Mike Casselton]

 

[moosemeat]

When glass bedding did you fully bed the recoil lug? Have you tries higher torque on the action screws?
Weird that my SPR also has a inlett that looks like it was done by a emotional support animal as well. It's also bedded now but it's a legit .5 MOA rifle.

 

[diggler1833]

View attachment 7903913

Yeah, but it is way worse...that flier would be over by Brandon's head.

 

[diggler1833]

When glass bedding did you fully bed the recoil lug? Have you tries higher torque on the action screws?
Weird that my SPR also has a inlett that looks like it was done by a emotional support animal as well. It's also bedded now but it's a legit .5 MOA rifle.

The bedding was one of my concerns, as I did it myself. I have done a dozen or so other rifles that are issue free...but I am no professional. I am certainly never free of potentially being the point of failure in any system.

To answer your question: Yes, I fully bedded the action and recoil lug, to include a pad about an inch and a half in front of the lug. I've gone back and forth about that pad under the barrel, but to be honest, I've done both ways and can't swear that it makes a difference.

My first gen SPR is skim bedded, and I did the pad under the barrel...it is a legit, consistent 1/2 MOA rifle with 165gr Nosler BT...and it was the rifle that shot the .7 MOA group at 170 when I was testing the handload for my bad SPR.

My FN SPR A2 was bedded under the pad, but I removed that pad when I rebarreled it to a 6.5x47 with an M24 contour (larger near the breech/chamber as the M24 has a 1.200 diameter and the FN barrels are 1.140 with a little less taper...fortunately they fit in the channel without effort). However that A2 now only has the action bedded, but the rifle is proving to be a laser too. It was a solid 3/4 MOA gun in factory form with the bedding job...I've thrown multiple 1/4 - 3/8 MOA groups doing load development with it now that it is a 6.5x47 with a Krieger barrel.

I really inspected my bedding job hard when I tore the rifle down. I didn't find any cracks or chips or voids. The fact that the groups would uniformly open up under moderate charge weights to where I could compete in a sporting clays competition makes me think that the consistency issue could be somewhere else.

I bought this gun in 2019, and it looked brand new considering it was 10 - 15 years old...now I think I know why it barely had any rounds through it.

 

[hafejd30]

Always try a proven optic before jumping to conclusions about the gun

 

[diggler1833]

Here's my last and final target before I said "screw it" and ordered a new barrel. It's a mess, so I'll explain:

Group on upper left was me testing out the bottom of the flier node to see if I could get get that one shot back in by dropping charge weight even more...nope, flier 2-1/2" or so to the 4 o'clock. When I get into the 42.4-42.7gr range, it'll put 4 shots into the .4s...but there's always that damn wild one.

Group on upper right was in the node where the groups sucked, but hadn't gone full shotgun pattern yet (were 3" with this combo another grain higher). At least the flier is gone, but 1-1.5 MOA is all it will ever do here. *I've never had the flier in this node...only the lower nodes.

Group on bottom left is my one experiment with a light charge and the 168gr Hornady AMAX. Ho-Lee-Fuk...I've never had a factory rifle produce a group like that at 100 yards. Mr. Mosin would be proud. I tried two more rounds next to it before calling it a day. Yes, that is a 5-1/4" group...I tested another load of that in my good SPR, and it shot MOA...so it isn't the load.

* I want to add that after looking at my notes...I AM chasing zero as I go between the nodes. Looks like a about a 1/2 mil shift.

 

[diggler1833]

Always try a proven optic before jumping to conclusions about the gun

Yep...but that scope has been on another rifle without issue.

 

[BScore]

I have a push feed Model 70 Sporter Varmint in 308, it threw flyers like it was it’s job. Always 2 close and 1 floating out in space. Tried everything I could think of. I bedded it into 2 different stocks, played with action torque (3 screw variety), put 3 different scopes on it, lapped rings/bedded the base, had my brother shoot it several times and tried about everything I could get a hold of reloading wise. Nothing got rid of the flyer. I was about to order a barrel and that same brother told me to cut the barrel down as there was nothing to lose at this point. So, grabbed a hacksaw and went from 26 to 20 inches. Did a half ass job of truing up the muzzle with some files and did a brass screw/lapping compound crown on it. And... so far, so good. Shot ladders of 168 Berger classic hunters and 168 eldm’s, the Berger’s were between 3/4 - 1”, eldm’s were slightly better. It was a lightly shot factory barrel, the crown was in good shape, but I guess it didn’t like the harmonics at that length.

 

[Mike Casselton]

Yep...but that scope has been on another rifle without issue.

It's still worth eliminating it as a possibility.

 

[diggler1833]

I have a push feed Model 70 Sporter Varmint in 308, it threw flyers like it was it’s job. Always 2 close and 1 floating out in space. Tried everything I could think of. I bedded it into 2 different stocks, played with action torque (3 screw variety), put 3 different scopes on it, lapped rings/bedded the base, had my brother shoot it several times and tried about everything I could get a hold of reloading wise. Nothing got rid of the flyer. I was about to order a barrel and that same brother told me to cut the barrel down as there was nothing to lose at this point. So, grabbed a hacksaw and went from 26 to 20 inches. Did a half ass job of truing up the muzzle with some files and did a brass screw/lapping compound crown on it. And... so far, so good. Shot ladders of 168 Berger classic hunters and 168 eldm’s, the Berger’s were between 3/4 - 1”, eldm’s were slightly better. It was a lightly shot factory barrel, the crown was in good shape, but I guess it didn’t like the harmonics at that length.

You could have had a reverse taper in the bore too, like Fisher noted above. Heck, maybe that is exactly what I've got. Either way, sounds like you fixed your problem. I'm glad you got it worked out. My solution is a bit more expensive. Thanks for sharing your problem and solution.

 

[moosemeat]

I recently had a scope win a mid range match with a few moderate fliers, nothing horrible just not where I thought they should have been. Next time I shot it 3" groups. Checked everything, rings, mount, barrel cleaned, and tries again. Random shotgun groups. Put my other scope on and back to .5 moa. Sent the scope in and the manufactor is sending a new one. They said it was beyond repair.
Point being scopes can shit the bed like a switch, or gently go over time. I would give that a check.
How does your other feed the 6.5x47? That's what mine will most likely be by the end of next season. Maybe sooner.

 

[BScore]

You could have had a reverse taper in the bore too, like Fisher noted above. Heck, maybe that is exactly what I've got. Either way, sounds like you fixed your problem. I'm glad you got it worked out. My solution is a bit more expensive. Thanks for sharing your problem and solution.

Good luck moving forward. My experience was damn frustrating, took about a year to sort out. If you’ve narrowed down everything else and are going to drop 1k on a barrel and installation, might as well cut it and give it a try.

 

[shoots100]

Yep...but that scope has been on another rifle without issue.

It would suck if you spent the money and time to re barrel it and found out afterwards that the scope shit the bed.
Now if you put that scope back on another rifle and shot bug holes, you know it's not the scope and can go from there.
Borescope, recrown would be my next approach before spending money to have it re barreled.

 

[Baron23]

Yep...but that scope has been on another rifle without issue.

Yes, but if I understand correctly...that was then, not now. For example, have you pulled that Burris off, put it back on that other rifle, and everything was wonderful? Just because that scope functioned flawlessly before on another rifle, doesn't necessarily mean that its still flawless after being reinstalled on this rifle.

Do you have another optic that you can put on this gun? This would help to isolate the fault to the optic or the rifle, right?

 

[diggler1833]

So against my better judgment since I'm 12 days post shoulder surgery (non-firing at least, but had rotator cuff, labrum, and clavicle done), I loaded 10 rounds of a confirmed handload node (albeit in virgin Lapua brass), and put my XTR II back on my FN SPR A2 that is now a 6.5x47. This rifle is still in the beginning stages of load development, but is showing some promise with ~145 rounds through it. I still haven't formed all the brass yet, but everything is basically on hold for a while now (obviously).

The load I used, is the one on the far right of the test target where I threw a called flier (below). *** This is perfect, because I frigging chunked a shot that day...as I can and do pull shots from time to time (usually about 1:40 or so...I'm not perfect). At least I can redeem myself (potentially).

I had intended to zero in 2 shots, and then shoot 5 more. Glad I loaded a couple extra because it too me 3 shots to zero close enough for government work. Guess I can put my bad-ass card away. Not going to lie, even the little 6.5x47 hurts to shoot right now. Here is today's 5 shot group:

I don't think I'd call it redemption. I was tensing at every shot, but at least no fliers. I know that a 5 shot group is not an ultimate test, but I never got 5 shots to group well when this scope was on the other rifle.

Fortunately, I had a spare set of 34mm rings...unfortunately, none of my .223s wear a 34mm mount as that would have been much better on me at the moment (shit...I just realized that my back door rifle does...oh well).

The worst part is that my wife heard the shots from across the ranch, and now I'm in trouble. For those who don't know, she's a Veterinarian, and I am on a strict recovery regimen.

 

[diggler1833]

Yes, but if I understand correctly...that was then, not now. For example, have you pulled that Burris off, put it back on that other rifle, and everything was wonderful? Just because that scope functioned flawlessly before on another rifle, doesn't necessarily mean that its still flawless after being reinstalled on this rifle.

Do you have another optic that you can put on this gun? This would help to isolate the fault to the optic or the rifle, right?

You absolutely understand correctly boss, as do the other guys who suggested this. My point in avoiding it until today (see post above) was that I was able to recreate both the 4+1 group as well as the unimpressive 1 - 1.5 MOA group with loads in the same two ranges on my last outing before I gave up on it. It would have been pretty unlikely that I could do that by chance.

However, my broken-ass took 8 shots today with that old scope, so I could shoot a re-shoot a group that I screwed up on during a previous load development...call it two birds with one stone with the scope and load test.

 

[Baron23]

You absolutely understand correctly boss, as do the other guys who suggested this. My point in avoiding it until today (see post above) was that I was able to recreate both the 4+1 group as well as the unimpressive 1 - 1.5 MOA group with loads in the same two ranges on my last outing before I gave up on it. It would have been pretty unlikely that I could do that by chance.

However, my broken-ass took 8 shots today with that old scope, so I could shoot a re-shoot a group that I screwed up on during a previous load development...call it two birds with one stone with the scope and load test.

Well, since you checked everything and moved the scope to another rifle and the problem didn't go with it, you initial take that it was the barrel seems like a very likely suspect. Yeah?

Best of luck with your shoulder recovery. I understand it takes time and lots of PT, but if you do the work you then you can have a great outcome. Hate to say it, but your wife is right....haha....stop shooting for a while. Let it heal, mate.