copper fouling on magna-port

Takujualuk

Takujualuk

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Whitehorse, Yukon
I have a used 358 Norma Ruger that I like very much but it has been an irritating gun to get to shoot. Had a plastic stock that it shot loose of regularly. I fixed with a reinforced Walnut stock from Ted..(Why-Not)

Now it shoots well for 15-20 rounds or so....sub-MOA well. Then accuracy slowly declines to about 2-3" groups as really bad copper fouling builds up on the magna-porting. Anyway of fixing this other than cutting off the barrell short of the ports to 19"?

How much ballistically a 19" 358 Norma lose?
 
Curious. There must be a burr causing the fouling to build up in that area. I shot a magna-ported Sako .300 Winchester for some time, and I do not recall an unusual build up of copper around the ports. Sounds like a trip to a smith is in order to resolve that one, but if it is a burr I am sure it can be ironed out.

I would expect a .358 Norma would loose about 25 fps per inch that the barrel was shortened - less with heavy bullets.
 
I have 3 guns I build with Magna ports, and I have not seen this at all.
However i suppose its very possible, but the magna ports are not cut i believe there chemicaly done! I hope i am not wrong on saying this, i did have 3 of them sent to the left coast to get em done?
one on a 375 epstien, the other a 350 mashburn, and the 3rd on a 7mm rum.
 
I have owned guns that were magnaported and have never seen what you are describing. The ports are done using EDM (electrical discharge machining) and this process does not leave any burrs or machine marks since there is no actual contact or tools involved.
What exactly do you call fouling on the ports?
How many ports do you have and how are they shaped and positioned?
bigbull
 
bigbull said:
I have owned guns that were magnaported and have never seen what you are describing. The ports are done using EDM (electrical discharge machining) and this process does not leave any burrs or machine marks since there is no actual contact or tools involved.
What exactly do you call fouling on the ports?
How many ports do you have and how are they shaped and positioned?
bigbull
Click to expand...


X2 thats what I was trying to say and I agree, could not for th elife of me remember its EDM tooled.
 
4 ports in total... two pointed up at a 45 degree angle or so and close to the muzzle and two more at a horizontal position a bit further back. Lots of blue streaks from the Barnes CR10 in this area. I actually resorted to using Q Tips coated in CR10 to douse the area.

Can't feel a burr. Not sure what to make of this or how to fix it. There is copper build up at all 4 ports. Nearly clean now but a bit more elbow grease is needed.
 
Clearly something is causing your problem, but if not a burr then what? If you are cleaning with a high ammonia content cleaner to remove copper fouling, I wonder if some got into the ports, and you were not able wipe it out. Perhaps the ammonia caused some pitting inside the bore at the ports, that results in fouling being blown into the ports from copper particles suspended in the propellant gas.

A close look with a bore scope couldn't hurt, and if you discover the problem let us know.
 
Every gun is different, 20+ rounds may be all your gun will tolerate before needing to be cleaned. I generally clean mine every 12-20 rds anyway. Bit of a pain but maybe just clean it more often.
 
Boomer said:
Clearly something is causing your problem, but if not a burr then what? If you are cleaning with a high ammonia content cleaner to remove copper fouling, I wonder if some got into the ports, and you were not able wipe it out. Perhaps the ammonia caused some pitting inside the bore at the ports, that results in fouling being blown into the ports from copper particles suspended in the propellant gas.

A close look with a bore scope couldn't hurt, and if you discover the problem let us know.
Click to expand...

I would tend to agree with this senario. I cant see how copper could otherwise find itself in the ports since they is actually no contact between the bullet and the ports. A soft pipe cleaner might just do the trick for cleaning this area out.
bigbull
 
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