interesting barrel run in

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bruce moulds
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Joined: Sun Jun 19, 2005 4:07 pm

interesting barrel run in

#1 Postby bruce moulds » Sun Mar 24, 2019 6:33 pm

i have a barrel that was run in and fired about 200 shots, but always fouled copper badly.
being anal about running in, this was most annoying, so the barrel ended up in the cupboard for some years.
a recent viewing with a borescope showed the leade/throat angle to be rough, almost like a file.
as an experiment it was rechambered to see if that was the problem.
now the rifled part of the barrel was run in, so the only real running in was the throat and leade.
the fifth single shot was cleaning up markedly better than the first, so went to 2 shots, and the 3rd pair was easier to clean than the first, so went to 3s.
the 2nd 3 cleaned easier than the 1st, so shot a 5, and it cleaned better than the 1st 3.
then ran out of time.
while not fully run in, it is on the way, and showing signs that something is happening.
all that was being run in was as suggested above, and this is not dissimilar to a new barrel, suggesting that Krieger and bartlein have it right in their running in description.
in 20 shots the touch the lands length became 0.005 longer.
I have noticed over the years that this throat lengthening goes away after a number of shots, suggesting that running in happens until then.
serious roughness in this area could well be smoothed more by flame erosion than being burnished by projectiles.
if this is the case, using lighter loads to run in will cause more cleaning and with it the potential for bore/crowning damage.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880
http://youtu.be/YRaRCCZjdTM

bruce moulds
Posts: 2900
Joined: Sun Jun 19, 2005 4:07 pm

Re: interesting barrel run in

#2 Postby bruce moulds » Mon Mar 25, 2019 6:08 pm

further to my wondering if most of barrel run in is due to flame blasting the tool marks out of the leade/throat angle, I remembered this.
a guy I know who can really get rifles to shoot runs in a little differently than average.
he mixes graphite with acetone and coats the bore with it after every clean.
the acetone quickly evaporates, leaving just graphite.
the first 2 shots he might clean, then goes straight to 5 shots between cleans.
in this situation he is prioritizing, deliberately or otherwise, flame blasting the leade angle over burnishing the bore with a bullet.
if my rifles shot like his I would be most happy.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM

Wal86
Posts: 319
Joined: Sun Nov 20, 2016 5:10 pm

Re: interesting barrel run in

#3 Postby Wal86 » Mon Mar 25, 2019 7:17 pm

- tool marks in the lead/throat?

(Polish a seated bullet in 000 steel wool... there should be no interference in the lead/throat...)

- throat/freebore measurement increasing during the break in process?

Both of the above should not happen....

Im very particular about breaking in barrels, but i dont do it for the above reasons.

Some break in and some dont bother.. I recently watched a video posted on this site with Mr Krieger explaining his opinion about barrel breaking in and barrel cleaning/maintenance..
I couldnt of disagreed more :lol: makes this game more interesting i guess :lol:

Cheers

Alan
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bruce moulds
Posts: 2900
Joined: Sun Jun 19, 2005 4:07 pm

Re: interesting barrel run in

#4 Postby bruce moulds » Mon Mar 25, 2019 7:43 pm

alan,
leade/throat ANGLE.
the bit that is usually 1.5 degrees.
reamers leave scratch marks there at right angle to axis of bore.
until these are smoothed out they can act like a file on the bullet.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM

Wal86
Posts: 319
Joined: Sun Nov 20, 2016 5:10 pm

Re: interesting barrel run in

#5 Postby Wal86 » Mon Mar 25, 2019 7:49 pm

I know what the lead and throat is Bruce...

Im unfamiliar with tool marks in the lead/throat and the freebore measurement shifting during breaking in process..

Both are related to one another, and im aware that others experience this. My point is that it should not happen...
Last edited by Wal86 on Thu Feb 06, 2020 7:11 pm, edited 3 times in total.

bruce moulds
Posts: 2900
Joined: Sun Jun 19, 2005 4:07 pm

Re: interesting barrel run in

#6 Postby bruce moulds » Mon Mar 25, 2019 7:54 pm

looking at an enlarged picture of the bullet above makes me wonder haw many shots that barrel has fired.
the rifling mark seems longer on the edges than in the middle.
could this be irregular erosion taking out the middle of the land on the leade angle?
this was common in 6.5/284 barrels years ago, to the extent that some almost got knife edges on the sides of the lands.
maybe some other reason for the irregular shape?
you say throats should not erode during running in, but I and others have experienced this,
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM

bruce moulds
Posts: 2900
Joined: Sun Jun 19, 2005 4:07 pm

Re: interesting barrel run in

#7 Postby bruce moulds » Tue Mar 26, 2019 6:59 am

another interesting observation is that cartridge loaded length to touch the lands can be different when the barrel is fouled compared to when it is cleaned.
if you are jamming bullets, does this mean that the amount of jam varies as more shots are fired?
could jumping bullets significantly have an advantage in this situation assuming good grouping?
I do recall a 6.5/284 barrel that shot berger vld better jumping than jammed.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM

Bigtravoz
Posts: 293
Joined: Sat Apr 22, 2017 7:43 pm

Re: interesting barrel run in

#8 Postby Bigtravoz » Sat May 04, 2019 11:01 pm

bruce moulds wrote:further to my wondering if most of barrel run in is due to flame blasting the tool marks out of the leade/throat angle, I remembered this.
a guy I know who can really get rifles to shoot runs in a little differently than average.
he mixes graphite with acetone and coats the bore with it after every clean.
the acetone quickly evaporates, leaving just graphite.
the first 2 shots he might clean, then goes straight to 5 shots between cleans.
in this situation he is prioritizing, deliberately or otherwise, flame blasting the leade angle over burnishing the bore with a bullet.
if my rifles shot like his I would be most happy.
bruce.


Graphite is carbon and don’t the experts tell us that carbon is bad?

bruce moulds
Posts: 2900
Joined: Sun Jun 19, 2005 4:07 pm

Re: interesting barrel run in

#9 Postby bruce moulds » Sun May 05, 2019 8:42 am

yes trav that is what I wondered too.
however you have to ask the questions.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM

Bigtravoz
Posts: 293
Joined: Sat Apr 22, 2017 7:43 pm

Re: interesting barrel run in

#10 Postby Bigtravoz » Sun May 05, 2019 3:19 pm

bruce moulds wrote:yes trav that is what I wondered too.
however you have to ask the questions.
bruce.


And if lucky you get the answer

bruce moulds
Posts: 2900
Joined: Sun Jun 19, 2005 4:07 pm

Re: interesting barrel run in

#11 Postby bruce moulds » Sun May 05, 2019 3:25 pm

trav,
sometimes you get the chicken and sometimes you get the feathers.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM


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