I just installed a new Savage {OME} heavy weight barrel in 308 on my switch barrel Savage rifle. This will be a deciated cast bullet only barrel and potentional “postal match” set up.
Are there any tricks to a new cast bullet only barrel break in ??
Wayne
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I bought a Zastava mini in 7.62x39, and the barrel as it came was a horrid scratchy mess with tool marks and obviously no attempt had ever been made after cutting the rifling to smooth the bore what-so-ever. I shot about 200 paper patched bullets, nothing on the patch but the calcium from our "soft" water here, and the barrel smoothed out nicely. It no longer grabs patches that go through and the bore is much smoother to the feel of my hand when I clean it.
B.E.Brickey
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As a subscriber to Precision Shooting magazine, I remember writer Merrill Martin doing a lot of work with wads under the cast bullet. He also gave people barrel lapping kits that included small containers of abrasive, ranging from coarse to fine.Never did see follow-up reports on the results people had.
Tom
Ed Doonan obtained a kit and did four barrels. He published a report in a letter to friends, I do not believe this report was published in The Fouling Shot. The barrels were; 1) new custom barrel, 2) a new factory barrel, 3) a used custom barrel shot approximately 3,000 rounds, 4) a well-worn barrel. He tested before and after lapping using ten-shot groups as his criteria. I'll summarize what I remember.
The results were:
The new custom barrel showed no improvement.
The new factory barrel showed some improvement.
The used custom barrel show some improvement.
The well-worn barrel showed no improvement.
His thoughts:
The custom barrel was already factory lapped, thus needed no improvement .
The new factory barrel probably still had some machining marks left needing some help.
The used custom barrel needed some smoothing, possibly in the leade area.
The worn barrel was a worn barrel and nothing could help it.
This is a short summary from memory, Ed included the size of the groups. If I can find the letter, I'll submit it for publication in The Fouling Shot.
Farm boy from Illinois, living in the magical Pacific Northwest
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For my prarie dog rifles and my CBA match guns I never fooled with the "break-in drill". As a subscriber to Precision Shooting magazine, I remember writer Merril Martin doing a lot of work with wads under the cast bullet. He also gave people barrel lapoing kits that included small containers of abrasive, ranging from coarse to fine. You lubed the cast bullet and then rolled the bullet over a layer of the abrasive to get the abrasive to "stick" to the lube, then fired the round. X number of shots with #1 abrasive, then X number of shots with #2 abrasive, etc.
Never did see follow-up reports on the results people had.
Tom
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When you mill something on a lathe or mill do you just leave the surface with the tool marks? If you do your work is not pleasing to the eye. If you milled a receiver would you leave all surfaces as milled or polish or lap the mating surfaces together?
Should you lap? Will it hurt? Answers are nebulous. John is correct in that there is no way to experiment to prove either way. We are left with antecedents. It has worked for me. Would my rifles have been better if I had not used JB Bore paste? Doubtful,
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Thumbs up for Mr. Ed. Harris, when he said, that he would not use any lapping compounds in a new barrel, that is exactly my thoughts. Sometimes with old junk barrels, I would be enticed to do something of that sort, but not with a new barrel. here is something to think about; Take a buffing wheel and try to buff the receiver of rifle that has some square corners and has a tangent to a curve. Most of the time unless you are very experienced with a buffing wheel, you will round these corners off. When I run something down a bore, even to clean, I want that tight fitting patch, backed up by something perfectly round and firm. That is why I feel that firing with jacketed ammo and frequent cleaning is the best bet. That way you're not going to round off the edges of the landMashburn
David a. Cogburn
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Hello John,
I agree with, you that the bore break-in has to be done with the initial firing, and like you said, you will never know what you accomplished. The only thing that I can say for sure is, I broke in all of my prairie dog gun barrels this way and I guarantee you that it is a great start to have a rifle that will fire many rounds before it fouls. And like I said, I started with good barrels. A rifle barrel that is smooth enough to stop a lot of fouling, should also be an accurate barrel. thanks John.
Mashburn
David a. Cogburn
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The trouble with barrel break in is because, according to most, it has to be done at the initial firing there is no way to test whether it does anything. You either do it or you don't at the start no trying the other way.
As one data point, Tony Boyer the GOAT of benchrest shooting doesn't do it.
John
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I only have 30/06 match rifles. I shoot 10 USGI AP rounds, clean and start shooting cast.
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I have always broken rifle bores in this way. I USE NO ABRASIVE PASTE. I shoot one round and clean, and I do this for 5 rounds, cleaning after each shot. I then shoot five rounds and clean and continue this five shot and clean until I have fired a total of 50 rounds. I class rifle barrels into three groups ,foulers, semi-foulers and non-foulers.
I know nothing of the top ideas are for cast bullet barrel break in, but I do know they must be slick. These are jacketed bullet barrels that I have always broken in this way, Let's face it, some barrels are junk and not matter what process you follow, they aren't going to be good barrels, no-matter what you do. You know the old saying, that you can't make a silk purse out of a sow's ear.
Mashburn
David a. Cogburn
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I have used 000steel wool and lapping compound to open throat for precise bullet fit using bumped boreride bullets. I would not be afraid to use 000steel wool and some type of fine compound to remove sharp edges inside factory barrel before final breakin.. Such as shooting jacketed bullets and cleaning frequently between shots.
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One pull with a Hoppe's BoreSnake loaded with Chrome polish per my method is more effective than 20 passes with JB loaded patches.
My polishing method is 100 pulls with the snake loaded every 10 pulls with Turtle Wax Chrome polish and rust remover that is 500 grit that cuts chrome and brings it to a high shine.I regularly get happy reports.The only negatives are from people that make substitutes and change the method or do it incompletely.GaryAbove is a reply from Gary detailing his method. I've not tried it. I might this winter since I want to clean up the bores on several prairie dog rifles.
Farm boy from Illinois, living in the magical Pacific Northwest
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I want to see Gary’s method but, the updates to the CBA has rendered the page closed. Any assistance would be appreciated.
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I've seen this many times, your pictures are excellent and display what I have told you about my polishing method. You refined your bore finish significantly. It will require no break in at all now and will be easy to maintain. You could have tested velocity if the barrel was mounted. The polishing also gives a slight increase in velocity for the same load after polishing. If you have the opportunity, please post your pictures and make comment in my original post with your success story. That old post of mine still gets a lot of hits and your pictures and comments would be very supportive there:
http://castbulletassoc.org/thread/8364-my-bore-polish-method-to-shoot-better/
Just clean up your BoreSnake as discussed and it will be great for the range regimen cleaned and dry to aid in consistency. Pull the clean dry snake through 2x before a shooting session then once every 5 shots during the session. This regimen yields match consistency by aiding in lowering the ES statistic of velocity significantly.
I wish you the best in your application.
Gary
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Here are before and after pictures. Since the barrel was not mounted on an action yet, I used Gary's method. I did the full 100 passes with the bore snake. There are two before and two after. You'll have no difficulty telling which is which.
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" i tend to think too smooth is unlikely ... but this needs more testing"
Precision shooting published a test on this (1990's?), and that was the answer; once it reached point X it never got any better, just reflected more light..
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gary's method with the snake is technically correct as a polishing method .
i did a test with clover grits of 280, 400, 800, 1200 .. and the old ( aggressive ) .jb ... on polished steel plate samples ...
the 400 was the slowest i would use to do any polishing down of any significant tool marks in barrel steel ... the finer grades are unnecessarily slow ... the striations left by 400 ( or turtle wax 500 ) ... don't seem to detract from even 22 rf accuracy in match barrels . i believe shilen laps with 280 grit . i suppose any striations can be regarded as just small rifling .
i have seen comments that there is such as thing as too smooth a barrel ... i would need to see the documented tests for that ; i tend to think too smooth is unlikely ... but this needs more testing . my 1-example input to that is that in my match 22 rf barrel which shot about 0.6 moa i shot about 3 or 4 thousand rounds with jb in the lube through it .. it shot 0.6 before and after the test , and i could see no throat advancement with nose engraving or borescope . very shiny, however .
for a new factory barrel i would shoot 4 with 280 grit pressed into a mj bullet .. this for the throating burrs . then gary's snake treatment or equivalent for the rest of the barrel. i do use his turtle wax chrome polish to slick up gun actions , even took a little of the russian out of my own makarov rails ... impressive .
while on fire-lapping i had a buddy who kept fire-lapping his big-name match barrel until it shot ... after 40 firelap y tests failed he set it back and re-chambered .. ha... it never shot ... smooth wasn't the problem with that barrel ...
ken
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BHyett ypu said,
"I proceeded to run three hundred strokes; five strokes, remove patch, new patch, add J-B Bore Paste and do it again."
You would need 2,000+ strokes with your method to compare with my polishing method.
One pull with a Hoppe's BoreSnake loaded with Chrome polish per my method is more effective than 20 passes with JB loaded patches. My polishing method is 100 pulls with the snake loaded every 10 pulls with Turtle Wax Chrome polish and rust remover that is 500 grit that cuts chrome and brings it to a high shine. I regularly get happy reports. The only negatives are from people that make substitutes and change the method or do it incompletely.
Gary
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Either Gary's or Bud's methods work equally as well, having done both. With the barrel out, Gary's may be easier, but barrel installed I think Bud's would be. Just getting the “big chunks” flatten out will help, but polished bright does not seem to do anything extra.
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