Thread: I'm flummoxed!
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Old December 20, 2019, 23:31   #11
hueyville
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Location: Foothills of the Blueridge Mountains
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Just changing the torque value by a few pounds either way can greatly affect barrel harmonics. My custom bolt rifle builder has about five versions of his proprietary muzzle brake. After a build is nearing completion he shoots the rifle with at least three of them and based on which shoots the best he then custom makes a brake for the rifle that has correct fit and astethics. He may remove and modify the brake two or three times then make another modiflying it in slightly different degrees, different lemgths, rows of holes, etc till barrel shoots as well as he thinks possible.

I took him a used Remington 700 in 7mm mag that was shooting 2.25 MOA at 100 and worse as distance increased. He disassembled, shaved rear of barrel, recut chamber, cryotreated, fit muzzle break, worked over the factory trigger, bedded the action in factory stock after Blueprinting it, installing his preferred base and rings then handed me back a 1/2 MOA rifle out past 500 yards.

Bought a Browning Boss in 22-250 which he ripped apart, shortened barrel a 1/4" from rear and recur chamber, cryofroze, made slight alterations to the ports in the factory Boss adjustable harmonics brake, removed their horrid rubber bedding and properly bed it, blueprinted action, worked trigger and at 100 yards unless iron the target to get it flat and have a caliper can't measure group size as it appears to be a one hole group with five rounds fired. Have to bring targets home, set up ironing board and iron them nice flat and crisp then lay on my light table use for viewing slides and use a micrometer to figure out actual group size as it shoots in the tenths of an inch.

When send him a Bartlein, Shilen, Kreiger, Pac Nor, Douglas, etc along with a good action to blueprint it's amazing what I get back. But one thing I do with almost every build from home built 10.5" AR 15, 16" Ruger 10/22, new or used factory or custom rifle of rack at LGS I first properly mount a minimum of 24x scope, often 36x in good rings that have been lapped and after a break in cycle I then shoot to see what rifles potential is. Mostly I use a Vortex Viper PST 6-24x50*bought on a clearance deal so cheap ended up with three.

Some new rifles have rough bore if not hand lapped and will copper foul in just a few rounds. Some have out of square chambers if off the rack factory or crooked throat. But I take a cleaning kit, bore scope and thermocouple so see what temperature the rifle likes to shoot at and what temperature is too hot and groups fall apart. Have taken many lightly used factory rifles to range and discovered why owner traded it. Some would copper foul in only five rounds requiring lapping and proper break in before proceeding. Some I had to use a throating reamer to fix an out of square throat.

Others had to use a crown lap to stone out a small burr and some have even had to use a facing cutter followed by a champhering cutter then lap to repair crown on the bench at the range. Will get some odd looks when you insert a pair of cutters in the muzzle of a rifle and steel shavings start to drop but have seen some muzzles were out of square once looked really closely. Do not do this to your new rifle as its a factory warranty job if needed and I have bought so many used rifles with intent to only use the action for a custom build I like to play with them.

Have at least a half dozen rifles purchased for cheap as owner said he was trading because it didn't shoot. Some of these were respected local shooters and LGS took them at their word and paid them appropriate price for a rifle that needed rebarreled. After doing my best to diagnose issue, sometimes two and fix them on range suddenly a 3 MOA rifle after four groups was a 1 MOA rifle following throating, lapping the bore and stoning the muzzle. Take same rifle home and work over the trigger, rebed the action and it was sub MOA by a fuzz or three for cost of a few rounds and use of a few specialty tools. If planning on throwing a barrel away when buy a rifle it's the perfect candidate to teach yourself gunsmithing on especially diagnosing issues with the bore. I also take a chamber cast of all my rifles to use for handloading specific loads for it and to examine for chamber and throat imperfections.

For the past two to three years have kept a Vortex Viper PST 6-24x50*on top shelf of my rifle tool cabinet to benchmark all new buys and builds off of. Many are modified and same scope put on it after changes if has to be removed and keep tinkering till satisfied with a build, fixed a rifle found cheap with a minor issue or two or prove what I bought was an action for my rifle smith to use as heart of a custom build. When I am able to fix a donor rifle into a keeper get almost giddy.

You could be seeing an accuracy node caused by improperly lapped bolt but I seldom lap a bolt as that is my smith's job. I suggest you go buy at least three boxes of an affordable copper jacketed brass case ammunition plus a couple boxes of Federal Gold Medal 168 SMKs, get a good solid rest to shoot from, not something cobbled together differently each trip out, use a real front rifle rest and rear shooting bag (fill mine with #7 lead shot instead of sand) and after lapping rings properly drop a higher power scope in the rifle, higher the better as long as it's good quality. Now follow Howas break in procedure. I use Tubbs but requires specialty bore lapping rounds and if done wrong can ruin a bore. Howa's process works good with a factory tube and never seen it make one worse, always better.

You are going to clean your rifle a lot doing this so a Hoppes Universal Bore Guide (17 to 46 caliber with included adapters and costs a whopping $20) and a Dewey 30 to 308 Caliber Brass Muzzle Cleaning Guide at $7 using a one piece cleaning rod. This will keep you from hitting the throat with cleaning rod and from nicking or wearing one area of muzzle

Quote:
HOWA BREAK-IN PROCEDURE FOR GUN BARRELS USING JACKETED BULLETS

For the first ten shots we recommend using jacketed bullets with a nitro powder load (Most Factory Ammo). Clean the oil out of the barrel before each shot using a simple window cleaner (like Windex®) which will soak the oil out of the pores. After firing each cartridge, use a good copper cleaner (one with ammonia) to remove the copper fouling from the barrel. We do not recommend anything with an abrasive in it since you are trying to seal the barrel, not keep it agitated.

After cleaning with bore cleaner, clean again with window cleaner after each shot. Use window cleaner because many bore cleaners use a petroleum base which you want to remove before firing the next shot. This will keep the carbon from building up in the barrel (oil left in the pores, when burned, turns to carbon).

To keep the temperature cool in the barrel, wait at least 5 minutes between break-in shots. The barrel must remain cool during the break-in procedure. If the barrel is allowed to heat up during the break-in, it will destroy the steel’s ability to develop a home registration point, or memory. It will have a tendency to make the barrel “walk” when it heats up in the future. We have all seen barrels that, as they heat up, start to shoot high and then “walk” to the right. This was caused by improperly breaking in the barrel (generally by sitting at a bench rest and shooting 20 rounds in 5 minutes or so). If you take a little time in the beginning and do it right, you will be much more pleased with the barrel in the future.

Look into the end of the barrel after firing a shot, and you will see a light copper-colored wash in the barrel. Remove this before firing the next shot. Somewhere during the procedure, around shot 6 or 7, it will be obvious that the copper color is no longer appearing in the barrel. Continue the window cleaner and bore cleaner applications through shot 10.

Following the initial ten shots, you then may shoot 2 rounds, cleaning between each pair of shots, for the next 10 shots. This is simply insuring that the burnishing process has been completed. In theory, you are closing the pores of the barrel metal that have been opened and exposed through the cutting and hand lapping procedures.
My note, after following this procedure make sure and clean bore very well as ammonia residue left in bore will etch it and cause it to pit. Use a liberal amount of Hoppes #9 which of all things has ammonia but it's a different ammonia than found in household cleaners and can be left in bore forever. Notice their break in calls for twenty rounds fired five minutes apart. From here your finished with the Windex unless truck windows are nasty.

We take our next box of copper jacket, brass case mid priced ammo and then if have a thermocouple or non contact laser thermometer and shoot five shot groups as quickly as possible without letting barrel get hotter than 150° and clean using Lucas Oil Extreme Duty Bore Solvent between each group. I like Lucas products. After last group clean well and then let barrel cool but not too cool, needs to be warm between each shot but not hot. Now your ready to break out your match ammo but before you shoot your first group shoot one of your 150 grain bullets into the berm or spot on corner of target as a fouling shot to burn the residue from bore cleaner out.

Now shoot a five round group trying to shoot each shot with barrel warm but not hot. Look down bore and if do not see any obvious copper fouling shoot another five round group of the 168 grain match and clean. Then use another of the 150 grain bullets and shoot into berm or corner of target to foul the bore and burn off residual bore cleaner. Now fire two more five shot groups, clean again then use a third of the 150s as a barrel warmer and to burn off residual bore cleaner. Now fire the next twenty rounds of the 168 grain match at various distances and believe you will find it is grouping well at any range you shoot if using a solid rest and doing your job.

I would then take the rest of the 150s you have had trouble with and see how they group now. Bet it's significantly better. Remember most rifles from cold bore to warm bore will string vertically with first round low, second higher and third up where rifle wants to shoot. Could talk for hours about vertical stringing with a clean cold bore to a fouled and warmed bore. Moly coated bullets were designed to reduce vertical stringing in match shooting when not allowed to fire bore fouling and warming shots. David Tubbs sells a product called Tubbs Final Finish or Tubb Precision Blended Boron Nitride Bullet Coating Kit. I coat all my match bullets and varmint bullets with the Tubb boron nitride.

At 1,000 yards it closes a ten shot group by up to six inches vertically as first cold bore round does not drop nearly as much and onc ed barrel is hot the bullets don't climb as high. Since started using it about the time I began using a professional ballistics app, range finders have improved and Bluetooth linked annenometers my first round cold bore kill ratio on coyote and ground hogs has gone up 60%.

Beg, borrow or steal at least a 20x scope, follow the Howa break in process then work your way through 40 rounds of 168 grain SMKs increasing number of rounds between cleanings and believe your rifle will settle down. New barrels have a tendency to have open pores in the steel unless hand lapped by a company on the part of Bartlain and those pores collect copper getting bigger and fouling the bore till you get them closed and sealed. An inexpensive AR 15 build does not need such a break in process but a big part of a precision turn bolts accuracy will be based on its break in. Then as it wears pores, especially in area around throat will begin to open up again and why people who shoot high dollar rifles based on how much over bore they are will lap the throat every "x" rounds as pores open and cause copper fouling.

My 308s can go 1,200 to 1,500 rounds before throat needs lapping. My 7mm Practicals need throats lapped every 600 to 800 rounds and are scrap metal by 2,000 rounds. Same with 22 Nosler. My 7mm RUM needs throat lapped every 500 rounds and at 1,500 rounds barrel is shot. My 22 CHeetahs require throat lapping every 500 rounds and last 1,500 to 2,000 rounds but are cry treated and never fired with untreated projectiles. I break in my Bartlain barrels per their recommendation as do Tubbs to his. Some I have a hybrid break in and an agrees I've break in on melon it barrels because they are so hard.

The great thing about a very structured break in is it teaches the shooter to be strictured, have a precise way of working at the bench and gets a fair number of rounds down range breaking shooter into the rifle so it becomes part of you. After break in I will often pull my Viper 6-20x PST off and replace with a 1x to 3x red dot but know it's actual potential and based on how well it shoots it helps me decide which optic to put on. Some rifles purchased a 36x scope to put on top and after break in only got a 20x to 24x. Some were purchased for a 4-16x and shot so well topped them with a 6-24x or even a couple with an 8-32x they shot so freaking well. Break in conditions your bore under controlled conditions, teaches you a lot about its capabilities as work through the process and by time it's properly broken in you know any tweaks such as trigger work, better scope, etc it may be asking for.
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