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Barrel Heat - Diminished Accuracy or....

T

The38Super

Sergeant of the Hide
Full Member
Minuteman
May 10, 2020
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Save shooting my AR at 200 yards, I'm brand new to long range; just bought a B14 BMP in 6.5 CM, because of course that's what beginners get.
Anyway, I'm having some accuracy issues and can't afford $55 a trip only to chase my zero, like I did my last two range trips.
Here's what happened today. Because my ability to hit shit at the end of last range trip was FUBAR, I started by confirming what I thought was my 200 yard zero for Sierra MatchKing at 200 yards. I did this with 3, 2 round 'strings'. The hits in each string were nice and tight and close enough to fine tune a true zero. Except, when I threw a three round string at the target, my POI was quite a bit off from where I expected it, with a looser pattern than if I'd used a 12 gauge. So, being pissed about not hitting shit, I hammered 3 and 4 round strings until I finished the box of ammo (20 total rounds), with a couple of smoke breaks to cool myself and the gun. Shit was all over the place. Here's my question, followed by what I think is the issue. Can you get a barrel sufficiently hot in 20 rounds of 6.5 CM, slow fire to screw the pooch on accuracy?
BTW, my scope and mount are tight, with no changes from last range trip.

My ask is to potentially eliminate one cause in order to confirm what I think is the real one. The can I'm using on my gun is a Form 1 I built for use with my long 556 AR, and was bored fairly tight to that caliber. I really wanted to use this can, because it's the one best suited in my can library (nice big blast chamber, all heat treated baffles). I sourced a 6.5 alignment rod and everything just fit...barely. I'd attempted to disassemble the can multiple times to bore the cones larger, but the thing wouldn't budge. What I think is happening is the heat is expanding the cones, making the bores tight enough to screw my accuracy.

Any commentary / first hand experience on either front would be appreciated. In the meantime, the can in question is being boiled for an hour in the hopes of finally breaking down the Rocksett, so I can disassemble and re-bore.
 
First off rezero at 100 yards. What type of target are you shooting at? Bipod? Rear bag? Need to know more on your setup. But to answer 20 rounds slow fire would not cause your issues.
 
Check all the mounting screws, then check and make sure the barrel isn't touching anything.

Edit.
Not sure if you were shooting with the an when it started heating up and degrading. But if you were. Take it off and see what happens.

Pps. If you were shooting with the can the mirage can make you think your zero is wondering.
 
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Target - Champion sighting target
Bipod, rear bag
Zero'd with can, mirage cover in place

After another hour of boiling, the can (Model: Christy Turlington) is still sealed tight, so I plan to A / B tomorrow with the Bob model. Same type and quantity of cones, but an inch shorter and bored for .30 cal. I'd have thrown Bob on the gun this afternoon, since I brought it along for another gun, but installing a cold can on a hot gun may as well be asking for it never to come back off. I'd just build a dedicated 6.5 can, but I'm a bit lacking in employment at the moment and Form 1 cans aren't any less expensive than Form 4's.

Will report my findings after tomorrow's range trip.
 
If you're gonna spend the rounds anyhow, here's an idea(s):
- ditch the can; you're troubleshooting and this is a variable you don't need
- use bags, not a bipod; more forgiving of technique (if that's an issue)
- double check your optics mounting, your action screw torque, that your barrel is free floated, etc.
- shooting one or two rounds is firing a "sighter." Once you're on paper, send five with your very best technique

Use precision in your language as well as your shooting. That's not a semantic issue - when your rifle fails to group consistently, the question is how much variation are you seeing? Is it literally feet? Is it a few inches? Both are problems, but they are problems of a much different nature/degree.
 
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DJL2 said:
If you're gonna spend the rounds anyhow, here's an idea(s):
- ditch the can; you're troubleshooting and this is a variable you don't need
- use bags, not a bipod; more forgiving of technique (if that's an issue)
- double check your optics mounting, your action screw torque, that your barrel is free floated, etc.
- shooting one or two rounds is firing a "sighter." Once you're on paper, send five with your very best technique

Use precision in your language as well as your shooting. That's not a semantic issue - when your rifle fails to group consistently, the question is how much variation are you seeing? Is it literally feet? Is it a few inches? Both are problems, but they are problems of a much different nature/degree.
Click to expand...
Checked the optics mount again tonight; good
Will double check barrel float, but it's a chassis and is as it came from the factory.

My best groups, once everything started going to hell, were ~3-5" at 200 yards; using my very best shooting mojo. The uppermost hit in each group was where the gun was zero'd. The rest of the hits were spread downward, close to equal distribution laterally, with a bit of emphasis to the right.

And with that reflection, as well as a quick look down the tube, I've confirmed it's definitely the can, because the rounds are dispersing almost exactly 180 degrees opposite the baffle clips. I'd heard about super tight bores on cans negatively impacting accuracy, but my cans always had sufficient room for the application, so I never encountered it before. And this bore is super tight for a 6.5, with <.050 of space. Goes to show that just because an alignment rod for the caliber fits doesn't mean it'll work in an optimum manner.

Will throw Bob on for my first few shots tomorrow and that doesn't work, I'll run it sans can and publicly admit to being dumb.
 
good luck figuring out how you can make it all work for you at a cost you can live with . there is always 22lr and there are plenty of people shooting them out to 600 yards or more so why spend 55 dollars when 22 you can shoot 50 rounds per box still under 20.00 well until next week when the price of ammo jumps up another 10 dollars lol .
 
Superjet said:
And you decided to screw it on a 6.5 without confirming the I.D.?
Click to expand...
Figured I could shoot out the material that needed to go...

Or perhaps I didn't need to confirm the ID because I built the thing, then used a 6.5 alignment rod to ensure it would work. That was in my first post, but you can be forgiven for missing it, with it being lengthy.
 
acudaowner said:
good luck figuring out how you can make it all work for you at a cost you can live with . there is always 22lr and there are plenty of people shooting them out to 600 yards or more so why spend 55 dollars when 22 you can shoot 50 rounds per box still under 20.00 well until next week when the price of ammo jumps up another 10 dollars lol .
Click to expand...
I think I have it figured out. Once it's good to go, I won't shoot the gun <300 yards, which won't be super often. Granted it's still more expensive than 22LR, but my 556 does great at 200 yds
 
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How are you checking your screws? Using a torque wrench? Not knocking your handyness but I highly doubt a home brew can is going to give you the desired results you might be looking for.
 
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Well, I have to admit to being completely lost. Swapped bipod for bags, swapped back, started with 30 cal can, then no can and had no better accuracy than yesterday. The only thing that changed was how the spread was configured (i.e cluster, string, etc.) Even though I'd torqued my scope, rings, etc. with my honest to goodness torque wrench (and checked it again yesterday), I pulled everything apart, when I got home, but found nothing loose or out of place. Scope is known good - it was on my AR that was grouping <.8 MOA @ 200. Barrel looks great, with very minimal copper fouling. Ammo - Fed gold medal Berger.

I removed the action from the chassis, in case something may have lodged against the barrel, when reassembled after installing a Triggertech Primary. Nothing there, plus looking at my log, my only two solid groups came after the trigger swap.

User error? Not to the extent of my poor accuracy. I've pulled a trigger literally millions of times, as a USPSA and PPC (High Master) competitor; basic marksmanship is second nature. I'd done a ton of research on here, as well as other sources, before I pulled the trigger on my Bergara the first time. Plus, I've consistently gotten better groups at the same distance on the same range from an inherently less accurate rifle.

Next step will be to shoot 100 yards off the club's lead sled, when I feel like looking at the damned gun again. If accuracy still sucks, it'll go back to Bergara. Strike that; next step will be to try my AR prone (after I finish breaking in that barrel and validate accuracy).
 
Can you determine what the action is doing in the chassis? Is there rub marks from where it's touching it? Are they all even? Did you torque the action screw? If so try more or less.

What size groups are you getting? How are they shaped?
 
jbuck88 said:
Can you determine what the action is doing in the chassis? Is there rub marks from where it's touching it? Are they all even? Did you torque the action screw? If so try more or less.

What size groups are you getting? How are they shaped?
Click to expand...
No real rub marks; more evidence that there was contact where there should be. Nothing I could detect where there shouldn't be contact.
Because they're behind circlips, with one being super recessed, torque on the two action bolts were admittedly by feel. I did my best to get them about where they were, when I backed them out. So, try less torque on them?

Groups are averaging in the 4-5" range (I didn't grab my targets). Most of today's were blobs, yesterday's were blobs weighted 180 degrees from the silencer baffle clips. However, the group I shot without a can today was oriented in the same manner, but more of a string than blob.
 
I would spend the $4 on a hex bit that would let you torque the action screws. Then set them to the reccomended specs. If it is the same you could try a little more or less. I would go tighter before I went too loose though.

I don't know Bergara but i would expect better then 2-2.5moa from a modern rifle.

I would still suggest setting up at 100yds and staying there while your working on it.
 
jbuck88 said:
I would spend the $4 on a hex bit that would let you torque the action screws. Then set them to the reccomended specs. If it is the same you could try a little more or less. I would go tighter before I went too loose though.

I don't know Bergara but i would expect better then 2-2.5moa from a modern rifle.

I would still suggest setting up at 100yds and staying there while your working on it.
Click to expand...
I've not been able to find the torque specs noted anywhere. I have the hex bits; more a matter of dealing with the circlips and I hate those things.
Bergara has a 1 MOA guarantee, so that would be the least of my expectations.
Agreed on heading back to 100 for now.
 
Everyone can make a lemon. I would argue that marksmanship and technique might account for perhaps a .5 MOA, maybe a bit more, between an experienced shooter and a neophyte correctly applying the fundamentals to the best of their ability. It certainly won't turn a true 1 MOA rifle into a 3 MOA rifle. Truly poor technique can manage that easily, of course. That said...

<dusts off soap box>

Suppose we have what one might casually consider a 2 MOA rifle. The reality is that it's probably a 3 MOA rifle. That is to say, it's a 3 MOA rifle at a 99% confidence interval and one would expect 95% of the shots to be 2 MOA or better, and thus the casual observer would likely consider it a 2 MOA rifle. Of course, fully 68% of the shots would fall within 1 MOA. Such a rifle would have a roughly 1 in 3 chance of producing an MOA or better group for any three shots. There are a LOT of supposedly MOA rifles out there that just aren't. They are probably about a 1.5-2 MOA gun that regularly produces sub-MOA three shot groups.

At some point, you need to place the blame on the gun, one of its components, or the assembly thereof. The only question is which component and what to do about it. I feel your pain as I recently spent a princely sum recently to have a smith assemble and bed a rifle. They made a hash of the job and the rifle double grouped. Nothing to be done for that but to start over. That's true even if the manufacturer deigns not to help you out... after all, even a 3 MOA gun has about a 90% chance to produce an MOA group from a box of 20 rds.
 
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Only thing to add to the above is you could optimize projectile / load with more testing. I had a rifle that shot worse than yours with most projectiles, but loved one particular projectile, and shot amazing with just that one.
 
What are your cleaning methods for the barrel.Maybe check barrel crown for damage.Also if you are using different loads for SR vs LR it can take 10-12 round for barrel to settle.I once had a 2 inch shift in inpact when switching ammo RL-15 vs AA 2520 .
 
Hopefully, I'll have better insight later today.
The plan is to set up on a bench at 100 yards
Grab the lead sled that I think belongs to the club or worst case bag the gun.
Fire four, four round strings, one target per, no playing with the scope, unless I find I'm completely off the paper. First two will be with the original can, second two without.
Then, evaluate from there. If the groups still suck, I'll begin a conversation with Bergara. On the flip side, if the groups are nice and tight, I'm not afraid to admit to complete user error from the prone position.
 
I've a good friend that bought an HMR last year that ended being a solid 3 MOA rifle. Bergara made it right, but it took four months.

You haven't by chance checked the crown of your barrel have you?
 
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The38Super said:
Can you get a barrel sufficiently hot in 20 rounds of 6.5 CM, slow fire to screw the pooch on accuracy?
Click to expand...
I would say, possibly yes.
Sporter contour, hunting rifles are not the optimal tool for target shooting (whether long range, or not). Cold bore, with a follow-up or two- is what they're designed for.

Are you checking barrel temp (can grab the barrel and hold it)?
It's well known since about the time smokeless powder was invented that light contour barrels string shots when they get hot, which is why target/comp shooters go with the heaviest contour that's manageable for their application.

I do think it's odd that you say it can't handle 3...but does two fine.
That said, if the rifle puts two cold bore shots where they're supposed to go- and will do that time and time again if you let the barrel cool completely- I don't see how it could be anything else.
 
Just came back from the range and I've reached the unequivocal conclusion that I suck. Shot off of the club's rest as well as bags and am certain the gun's sub MOA capable, but my issues with getting and keeping a consistent cheek weld ensures I'm not. The group below is a perfect example. First two rounds go right where I want them. I come off the gun to adjust the bags, coming back in what I'm sure is the exact same spot, but the hit next to the 4 (string designation, not shot) says otherwise. The last round, I'm all scrunched up, praying I'm in the right spot, then place it on what may as well be another target.

I've posted a thread in the marksmanship sub forum, asking for assistance. In the meantime, the Bergara will get thrown in the safe, while I go back to basics on my newly rebarreled 18" AR.

Thanks to everyone for their input. Sorry the culprit wound up being lame trigger puller.

IMG_4984-2.jpg
 
You should listen to Frank's most recent podcast about the extent to which getting on the gun influences POI.

It could be that you're a terrible shot. I won't rule it out if you are sure that's the cause.

That said, the degree to which you'd need to mishandle the gun and the trigger to produce two inches of error at 100 yards is pretty significant. I've seen it... hell, I've seen that much POI variance at 25 meters from shooters that are especially challenged.

I feel compelled to add - the first time I ever got a sub-MOA bolt gun, I could regularly produce 5 shot groups of less than an inch using only what the Army taught me shoot the M-16/M-4 FOW. That's a kind way of saying I was (and still am) shit as a shooter/trigger puller. As I got better, I started shooting 1/2 MOA groups. My personal journey took me from being about a 1 MOA shooter to being a bit better and sometimes bumping the limitations of the rifle. You can go over to the KRG SOTIC thread if you want to read/see my rather boring/mundane journey.

Get your rifle into the hands of someone that knows how to shoot - if it really is you, it will be readily apparent.
 
OP, in my experience NPOA is a big deal in shooting groups. As well as the other fundamentals.
 
If this is your first, or you otherwise lack experience- it's prudent to consider shooter error as you've done.
If you're at the range and there's a more experience shooter nearby- let 'em drive it for a few rounds to see if they get a different result.

Bergara says their trigger leaves the factory at 3.7 lbs- and can be adjusted down to 2.8.
I'd suggest dropping the trigger pull that pound- it might make a difference for you. Not that one can't shoot well with a heavy trigger...but there's a reason why target/benchrest shooters use triggers measured in ounces. From my own experience, heavy triggers are tougher to master- as any deviation from a straight-back press will be evident at the target. Aside from that, there's a need to just become familiar with the trigger; take-up, creep, you need to develop a "feel" for exactly when the trigger will break. I think perhaps, you might just need more trigger time.
 
I'd been shooting my pseudo precision AR off the bench at 200 yards for well over a year, and getting semi-consistent ~.7 MOA results until the barrel decided it was defective. What always confounded me was I couldn't seem to muster <1 MOA at 100 with the same gun / ammo.

The stock trigger measured 2.5# out of the box. It was a decent trigger, but to your point, too heavy for solid accuracy. I installed a Triggertech Primary and adjusted it down to its min 1.5#. Considering this is a toy, I just couldn't justify the additional $100 for the next lighter option. The Primary is an easy trigger to get accustomed to and breaks exactly when you want it to. Almost 1911-like. In fact, it may be crisper than my custom USPSA Open gun, which also has a 1.5# trigger pull.

We have some great bench rest shooters at my club, so I'll see if one wants to throw some rounds through my gun, next opportunity. But I'm convinced my problem is how I set up behind the scope and how it's inconsistent, despite the effort I put into removing variation. This weekend, I plan on revisiting both scope eye relief as well as cheek riser settings and spend a bunch of time on finding my ultimate natural and repeatable cheek position. I wish there were an easy way to lock my rifle into a firing position, so I could jump behind it randomly and confirm I'm getting the exact same sight picture every time.
 
Practice practice practice. Only way to get better. Shoot lots and dry fire more.

That said practice while doing a little load development by yourself is always a good idea just because it’s focused trigger time where you’re hopefully keyed way in on it and taking lots of time.

When I was first getting started I was frustrated with myself until I found that load that worked and could watch it happen in front of me plain as day when a group finally printed well. I wasn’t a 2 moa shooter by that point but that old load was.
 
I'm sure there are those who've been lying awake, wondering whether they'd ever hear the loud sucking sound, that is me pulling my head out of my ass. The sniper's nest I set up in my hallway definitely helped to better set up the gun and play with where to stick my melon. I'd been using more of a cheek / jaw weld, which clearly wasn't repeatable. Popping down behind the gun at random intervals helped me identify a weld that was more consistent and repeatable. Also had to replace my rear bag. The one pictured above wasn't super stable and it drooled.

While I still have an aircraft hanger sized room for improvement, I'm pretty damned pleased with how much tighter my groups are. Four or five round groups would have been a better representation, but I have a finite amount of ammo and no job to fund another batch for $3million. My last string was a four rounder and the worst I shot today (eyes were going wonkey); it was .9 MOA at 200 yds.

All groups were shot from prone, using a bipod, and my sketchy (according to some) Form 1 suppressor.

Ballistic-X-Export-2021-09-15 20_23_45.473521.jpg
 
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Improvement is always gratifying. Now I don't have to send you photos of the crappy group I shot this weekend next to a less crappy group to highlight the influence of technique. The crappy group was totally on purpose... totally. ;-)
 
Updated update - I was finally able to participate in an informal 600 yard session at my club; pretty much the reason I bought my Bergara.
My ballistic calc app was dead nuts to 300 yards, but half a mil low at 600. Once I got that ironed out, I managed a solid 2 MOA with the rest of the rounds. Probably could have done better, but our club has an electronic system that shows your hits real time on your smartphone, and I lifted my head after each shot to see my hits. I'm really happy with my progress, but would like to get some experience with reading and correcting for wind. Our club has solid wind breaks around our rifle ranges, so I haven't needed to deal with correction. Made 600 pretty easy, tbh.

Unfortunately, this was the last session for the year, so I'll have to wait until spring to break the gun out again. We have rifle ranges up to 300 yards available all the time (600 is only available when there's supervision), but I can cover that with my 556.
 
The38Super said:
Just came back from the range and I've reached the unequivocal conclusion that I suck. Shot off of the club's rest as well as bags and am certain the gun's sub MOA capable, but my issues with getting and keeping a consistent cheek weld ensures I'm not. The group below is a perfect example. First two rounds go right where I want them. I come off the gun to adjust the bags, coming back in what I'm sure is the exact same spot, but the hit next to the 4 (string designation, not shot) says otherwise. The last round, I'm all scrunched up, praying I'm in the right spot, then place it on what may as well be another target.

I've posted a thread in the marksmanship sub forum, asking for assistance. In the meantime, the Bergara will get thrown in the safe, while I go back to basics on my newly rebarreled 18" AR.

Thanks to everyone for their input. Sorry the culprit wound up being lame trigger puller.

View attachment 7700665
Click to expand...
This leads me to believe it’s your parallax adjustment or lack thereof.
 
The38Super said:
Updated update - I was finally able to participate in an informal 600 yard session at my club; pretty much the reason I bought my Bergara.
My ballistic calc app was dead nuts to 300 yards, but half a mil low at 600. Once I got that ironed out, I managed a solid 2 MOA with the rest of the rounds. Probably could have done better, but our club has an electronic system that shows your hits real time on your smartphone, and I lifted my head after each shot to see my hits. I'm really happy with my progress, but would like to get some experience with reading and correcting for wind. Our club has solid wind breaks around our rifle ranges, so I haven't needed to deal with correction. Made 600 pretty easy, tbh.

Unfortunately, this was the last session for the year, so I'll have to wait until spring to break the gun out again. We have rifle ranges up to 300 yards available all the time (600 is only available when there's supervision), but I can cover that with my 556.
Click to expand...
This is where I channel @lowlight for your benefit. You adjust the software to the rifle, not the other way around. ;-) Check out weaponized math, download and print the sheet, fill in your DOPE as appropriate. Calculate your try DOPE as required for your next session.

There are some pretty good shooters on here that would tell you that aside from collecting DOPE and practicing your wind calls, shooting out to 300 yds isn't holding you back from putting in quality positional shooting practice.
 
I'm with @Elite_KG. If you are putting in a tight grouping, step away from the gun, and when you come back your shots land in another zip code, you are dealing with a parallax issue.

What scope is this? Sitting behind it, looking at your 200 yrd target, if you move your head left/right/up/down a little while you stare through the optic, does the target move relative to your reticle or does the cross-hair stay on EXACTLY the same point regardless of where your head is?
 
DJL2 said:
This is where I channel @lowlight for your benefit. You adjust the software to the rifle, not the other way around. ;-) Check out weaponized math, download and print the sheet, fill in your DOPE as appropriate.
Click to expand...
This is probably where I should mention 600 yards was the furthest I've ever shot a gun, any gun, so I didn't actually have DOPE info to work from. The ballistic calc got me in the ballpark and I adjusted from there.
 
BillyNg said:
What scope is this? Sitting behind it, looking at your 200 yrd target, if you move your head left/right/up/down a little while you stare through the optic, does the target move relative to your reticle or does the cross-hair stay on EXACTLY the same point regardless of where your head is?
Click to expand...
The scope is a Bushnell Forge 4.5-27 and the crosshairs move slightly, depending on head location. My issue has been a consistent cheek weld, which had been causing me to shoot like shit. I've improved leaps and bounds on that front and am shooting much tighter groups at 200 and 300 yards. But that's still not perfect.

Revisiting my data, I was in the 1.5 MOA range for the shots I fired after getting my elevation properly. I'm pretty darned pleased with that, for a couple of reasons. First, I had been shooting twice that @ 200 yards, with ultimate concentration (see pic in post #32) and not lifting my head between shots, so I'm shooting much better. Second, as I mentioned above, until Wednesday, the longest shots I've taken were at 300 yards and those were mostly to validate scope settings. So, despite my being a mature, intelligent man in his early 50's, my inner voice was screaming 'this is so cool! I'm shooting a target over a third of a mile away and getting X ring hits!' The only time my inner voice should be active, when I've got a gun in my hand, is while I'm shooting a USPSA stage and then, that voice is all business.
 
The38Super said:
The scope is a Bushnell Forge 4.5-27 and the crosshairs move slightly, depending on head location. My issue has been a consistent cheek weld, which had been causing me to shoot like shit. I've improved leaps and bounds on that front and am shooting much tighter groups at 200 and 300 yards. But that's still not perfect.

Revisiting my data, I was in the 1.5 MOA range for the shots I fired after getting my elevation properly. I'm pretty darned pleased with that, for a couple of reasons. First, I had been shooting twice that @ 200 yards, with ultimate concentration (see pic in post #32) and not lifting my head between shots, so I'm shooting much better. Second, as I mentioned above, until Wednesday, the longest shots I've taken were at 300 yards and those were mostly to validate scope settings. So, despite my being a mature, intelligent man in his early 50's, my inner voice was screaming 'this is so cool! I'm shooting a target over a third of a mile away and getting X ring hits!' The only time my inner voice should be active, when I've got a gun in my hand, is while I'm shooting a USPSA stage and then, that voice is all business.
Click to expand...

I can't tell if you know we're saying the same thing. Your consistency on the cheek weld means putting the eye in the exactly same position behind the scope every time to mitigate parallax issues. You can let your equipment help you with this by adjusting parallax on your scope.
 
I see you purchased some Hornady ammo, good call that is one of the ammo's recomended by Bergara .I have shot 4 different Bergara 6.5 creed rifles all liked the Hornady ammo the best of the brands tested.
 
Weaponized Math requires no inputs, you simply take your previous yard line dope and it will put you on target, usually center line if you are doing your part.

Ballistic calculators require certain validated information and even then are not always gonna give you the results you want.

if you start with 200, .5 mils or 2MOA and then double it for 300, you are gonna be in the ball park in a way you can adjust perfect to center. From there using weaponized math there is no Guessing, no maybe it will work, it works… perfectly.

You take your 300 yard dope, Mil or MOA and simply multiply it by 1.75, that give your 400 yards,

400 you multiply 1.45 and you have your 500 yard drop…

then 500 times 1.40x gives you 600 yards. No sight height, bullet weight, BC, or even MV, you just use your drop.
 
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