Barrel heat and grouping

[308rws]

Check the torques of your rail, bases and rings before you next shoot. If it reoccurs let the barrel cool remove the moderator and retry. Process of elimination i.e. ammo, mod, scope ... user. Ask a friend who can shoot to try and group with it. 50p group is fine with a new hot sporting barrel. Do not try any home riflesmithing of a new rifle. If it still doesn’t group take it back to wherever you bought it and get it sent back to the manufacturer/replaced.

 

[Utectok]

I’d say like others something is loose if it’s punching 3” groups. 99% of modern rifles will happily shoot a 20round string without opening up the group through heat in the barrel. I’ve never experienced it but some thin or badly stress relived barrels apparently have an issue. Usually it the rail action screws but it could be anything including optics.

 

[Heym SR20]

A hunting rifle that holds five shots in a 50p sized group is more than good enough for most hunting purposes.

New barrels do take time to settle down before they reach full performance. Any barrel is not perfectly concentric and as things heat up barrels will warp which means groups will open up. Target weight barrels help slow the process down as there is just more mass, and the effect of any lack of concentricity will be less.

Also you have the effect of yourself. You get tired - muscles, eyes and concentration as you shoot. A rifle is susceptible to how it is held and whether you have the same tension, pressure grip etc for each shot.

A typical shot string in target shooting is ten shots. I used to shoot 10 bull 22lr. It’s not that difficult getting 6 or 7 good bulls - it’s getting the last 3 or 4 that is the difficulty.

With a centrefire outdoors its even more difficult. Wind calls - even at 10mph makes a big difference to group size.

 

[Smellydog]

Going off memory they generally wandered left if that provides any more insight

Your barrel has not been stress relieved sufficiently. When it warms up it's bending.
It happens now and then.

 

[Smellydog]

but some thin or badly stress relived barrels apparently have an issue.

This^^

 

[BE Precision]

Some things to do/check when testing and setting up a new rifle.

Nothing is loose.
Barrel is free floating.
You are shooting from the same position, rifle is stress free and your head/grip/trigger pull are consistent (fundamentals of marksmanship).
Clean it (properly).
Clean it again (properly this time).
Don't let ammunition sit in hot chamber and warm up, shoot quickly.
Get a good target, aim small. Try the corner of a square or a cross.

Years ago, i and a Steyr Prohunter that had a similar problem, it ended up being a combination of flexible stock, inconsistent grip and a burr in the start of the rifling picking up cooper. Deep cleaning, time, forend stiffening and learning how to hold/shoot it finally got it shooting acceptably. Different shooters would get different POI and group size with that rifle. Even after it was sorted. Eventually its was moved on, but it taught me a lot.

 

[HonestJohn]

Did you park perfectly concentric to the white lines in the parking lot space? If not, this may have impacted on your deep psychological state and manifested itself in trigger squeeze that was slightly off.

Statistically you simply cannot rule it out, remember to take pictures and document everything that happens from the moment you wake up until the holes are in the paper, keep records and analyse every week for 20 years.

Eventually you might be able to draw the conclusion that at some point in time, you shot good groups, but cannot draw firm conclusions as to why. More importantly, you can see that with reloading and barrel wear, groups have opened up again, so it’s time to order a new rifle and start again.

Or even better - now and again, check on paper your first 2-3 rounds go in the bull or an inch above, then go buy more of that high performing factory ammo before retiring with a coffee and a booking to go stalking.

Am I starting to get old and grumpy?

 

[Smellydog]

It started to walk shots when it got hot.
He didn't describe the group, we didn't get the full story so I asked how the grouped opened up.
The next test is to see how it shoots the next three rounds. If they group but then on the fourth, fithe and sixth shot they start walking the barrel has stress in it.
Unless you understand how steel is rolled hammed and thrashed you won't appreciate possible stress lines.
All barrels after rifling are stress relieved, or should be however the occasional one doesn't get enough or is completely overlooked!

 

[kenbro]

I used a med loctite on my .270 and had 1 come lose in 7 years so just re did that one then in rotation on the rail.
Used to use nail varnish on the dive computers when I did a battery change so if it came back you could see it someone had been poking!

Devious some of theses divers, Tim….poke and re varnish!
Ken.

 

[HonestJohn]

It started to walk shots when it got hot.
He didn't describe the group, we didn't get the full story so I asked how the grouped opened up.
The next test is to see how it shoots the next three rounds. If they group but then on the fourth, fithe and sixth shot they start walking the barrel has stress in it.
Unless you understand how steel is rolled hammed and thrashed you won't appreciate possible stress lines.
All barrels after rifling are stress relieved, or should be however the occasional one doesn't get enough or is completely overlooked!

I think everyone probably agrees on this.

I once had a cut rifled and beautifully made Schultz Larsen barrel made by them for my Mauser 98 action 6.5x55. It was featherweight profile, and I could shoot 20 round groups within 1/2” without letting the barrel cool.

Now that’s a good barrel!

 

[kenbro]

This type of thread never ends well as to comment meaningfully you really need the rifle (setup) in front of you.

K

And a pic of the group as was suggested before.
Kb.

 

[Tim.243]

Devious some of theses divers, Tim….poke and re varnish!
Ken.

Not many had your colour Ken... pink

 

[Mungo]

Evening,

This weekend I’ve gone out and bought my first centre fire rifle, a .243 bergara b14 crest (steel barrelled). I took it out Saturday afternoon to zero it and began dialling it in starting at 50 yards and once I was happy moving out to 100, for the first 5 shots cleaning after every round as recommended by begara to break the barrel in. Once I got out to 100 I got it to within about a 50p after 5 or so shots leaving a few minutes between rounds before it started to open up quite drastically (shooting around 3 inch groups), the barrel was hot but not as much to the point you couldn’t still hold it. I know when zeroing a stalking rifle it ideally wants to be ambient temperature as to be the same as it would be when you take your first shot in the field but I was running out of daylight so wanted to get on. In short my question for everybody is - is this normal and can any harm be done to the barrel by allowing it to get hot? I know a hot barrel will affect a grouping to a degree but changing the group size from sub moa to 3+ inches seems slightly extreme. Any help, inputs or recommendations is appreciated.

How many shots did you fire at 100?

And how many shots in each group?

A picture of the target would be extremely helpful.

 

[Donkey Basher]

Aside from all the carp above, as already been mentioned, check all screws are tight & then check mod is tight. Position & alignment also affect grouping, make sure you are properly aligned to your target, have good contact with the rifle & that you are using consistent & solid rests for the rifle. Finally, also covered, as mod heats up it will cause mirage generated by surface heat & also escape of hot gases from the muzzle, both can cause poi to wander. Once you’ve ensured all is tight & you have proper rests to use, go & shoot 3-5 rounds as a group & see what it does.

 

[Cyres]

Is the barrel free floating when it is hot?
Try the £20 note test.
D

 

[JTO]

Read #20 and try another day when you have plenty of time.

MagnetoSpeed Riflekuhl Barrel Cooler | Compact Design | Easy To Carry

Our MagnetoSpeed Riflekuhl Barrel Cooler cool's your rifle barrel in under 7 minutes. Features replaceable dust filter and chamber seal for increased cooling efficiency.

www.wildcatmoderators.co.uk

 

[MarinePMI]

This has been my experience with SOME carbon barrels but not all. I also have a Crest Carbon but in 308, and it too starts to open up a little bit once the barrel starts heating up. My son shot a deer with it yesterday, as it is perfectly consistent when shooting just a few rounds.

A lot of times, with CF barrels, the "groups opening up" after a string of fire is due to the mirage a CF barrel makes when it sheds heat. This is a known issue amongst long range shooters, and why (one of the reasons) you don't see the military using them.

 

[MarinePMI]

Evening,

This weekend I’ve gone out and bought my first centre fire rifle, a .243 bergara b14 crest (steel barrelled). I took it out Saturday afternoon to zero it and began dialling it in starting at 50 yards and once I was happy moving out to 100, for the first 5 shots cleaning after every round as recommended by begara to break the barrel in. Once I got out to 100 I got it to within about a 50p after 5 or so shots leaving a few minutes between rounds before it started to open up quite drastically (shooting around 3 inch groups), the barrel was hot but not as much to the point you couldn’t still hold it. I know when zeroing a stalking rifle it ideally wants to be ambient temperature as to be the same as it would be when you take your first shot in the field but I was running out of daylight so wanted to get on. In short my question for everybody is - is this normal and can any harm be done to the barrel by allowing it to get hot? I know a hot barrel will affect a grouping to a degree but changing the group size from sub moa to 3+ inches seems slightly extreme. Any help, inputs or recommendations is appreciated.

Are you sure you're not just picking up mirage off your moderator? (I don't see a suppressor cover)

Try taking the Mod off and running the same test.

 

[C h r i s]

Is the mod still tight when the groups starts to open up? Seen this loads when the lightweight aluminium mod heats up and unscrews just a little., groups go to shite.