Gunsmithing Factory barrel cleaning?

[BoulderE89]

Hey, so I’m relatively new to precision rifle shooting, I just got my first gun this past Christmas. (Bergara hmr pro in 6.5 creedmoor in an X-ray chassis). I’ve shot it a couple times. 2 range trips and one prs match. The first time I took it to the range I thoroughly cleaned the barrel with wipeout foam before I went and after, which was about 100 rounds shot then. Then shot at the prs match and only wiped it down with some solvent patches afterwards which was about 70 rounds shot. I took it out again today to sight it in with a new chassis (krg X-ray to krg bravo) and my groups jumped from .6 moa to .9 moa - 1.0 moa consistently with the same ammo (federal 130g hybrid Berger). I don’t know how to trouble shoot this, is my jump in groups because I didn’t thoroughly clean my barrel like the first time, or would switching from a krg x ray chassis to a krg bravo cause that much of a difference?

 

[Gee Kay]

After a good clean most barrels like a fouling before they shoot tighter groups. At least that's my experience with my rifles.

 

[BoulderE89]

After a good clean most barrels like a fouling before they shoot tighter groups. At least that's my experience with my rifles.

So you think that the groups opening up will tighten back down as I continue to shoot it?

 

[Gee Kay]

i can only speak of my 223. i know after a good cleaning it takes a few shots before it will shoot nice tight groups, but that's my rifle.
in theory a barrel should tighten up once it has a nice layer of copper put down after a few fouler shots from clean.
Frank has done a podcast about cleaning and breakin, check it out...

The Everyday Sniper Episode 13 Rifle Cleaning & Break In | The Everyday Sniper

The Everyday Sniper Episode 13 Rifle Cleaning & Break In Frank here again, bringing you another episode of the Everyday Sniper. In this episode I talk rifle cleaning and barrel break in. I go through my methods of doing it. Don't forget to visit Sniper's Hide and give Mike a call over at...

theeverydaysniper.podbean.com

 

[BoulderE89]

So in theory (and generally speaking) if I shot around 50 rounds...would that be enough or would it be more before I saw it tighten again?

 

[Gee Kay]

should only need a few, with 50 you could do load development if you were reloading

 

[mick243]

yes the change of stock/chassis could be the cause of your group enlargement.

even if the bedding in the 2 stocks is perfect (and it likeley isnt, unless you spent time and effort doing it, or payed someone competent to do it for you) then things like slight differences in action screw tension can, resonances within the chassis etc can effect the poi and group size. even changes to your firing position/grip on the gun can effect things.


first, I'd put the original stock on, carefully noting torque values on the action screws. give it a clean, then a few fouling shots and shoot some groups. if its the same as before then so far so good. now put the second chassis back on it - again being careful to get the torque on the screws the same as the original stock (having said that, you may need to experiment later with bit more or less - one of my rifles is very tolerant of main action screw tension, but extremely sensitive to rear screw tension - I suspect thats because of the bedding in the wooden stock being uneven and flexing the action) and shoot some more groups - if the problem persists, now is the time to start experimenting by adjusting just one thing at a time and doing more group tests.

yes, cleaning it will effect group size, as will running it too dirty - you need to play around with it and see how many fouling shots required after cleaning, and then how many shots before group size increases indicating cleaning time again. every barrel is different in this regard

 

[BoulderE89]

yes the change of stock/chassis could be the cause of your group enlargement.

even if the bedding in the 2 stocks is perfect (and it likeley isnt, unless you spent time and effort doing it, or payed someone competent to do it for you) then things like slight differences in action screw tension can, resonances within the chassis etc can effect the poi and group size. even changes to your firing position/grip on the gun can effect things.


first, I'd put the original stock on, carefully noting torque values on the action screws. give it a clean, then a few fouling shots and shoot some groups. if its the same as before then so far so good. now put the second chassis back on it - again being careful to get the torque on the screws the same as the original stock (having said that, you may need to experiment later with bit more or less - one of my rifles is very tolerant of main action screw tension, but extremely sensitive to rear screw tension - I suspect thats because of the bedding in the wooden stock being uneven and flexing the action) and shoot some more groups - if the problem persists, now is the time to start experimenting by adjusting just one thing at a time and doing more group tests.

yes, cleaning it will effect group size, as will running it too dirty - you need to play around with it and see how many fouling shots required after cleaning, and then how many shots before group size increases indicating cleaning time again. every barrel is different in this regard

Ya, I’m think I’m gonna do another deep clean with wipeout foam and get out all the fouling and see what effect it has. If it doesn’t change then it’s the chassis I guess. This stuff totally feed the scientist side of me, just need to find the time to do all this testing. If it is cleaning is it a red flag if I start losing accuracy after only about 150-200 rounds?

 

[stello1001]

I would most likely believe it has to do with the mating of the action to the surface of your new bravo. It's probably not mating with the exact same torque values as before. How much torque did you use and how much torque did it have before?

 

[BoulderE89]

I would most likely believe it has to do with the mating of the action to the surface of your new bravo. It's probably not mating with the exact same torque values as before. How much torque did you use and how much torque did it have before?

65 inch pounds both times. Both chassis are from krg so the geometry of the metal backbone of the 2 is identical