| Posted: Mon Jun 4th, 2007 08:25 PM |
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pisces
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After about 250 shots my 17hmr barrel has built up a layer of carbon fouling, that can be seen when viewed from the breech, just after the leade.
Normally, this is when I use a wetted bronze brush to remove the fouling because it is widely attributed as being the cause of poor grouping due to bullet swaging.
However, my question is: If the bullet is swaged down by this restriction does the bullet expand further down the barrel so negating the swaging effect?
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| Posted: Mon Jun 4th, 2007 09:26 PM |
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72coupe
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I haven't seen any research on it but I doubt it considering the pressure that 17 HMR works at.
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| Posted: Mon Jun 4th, 2007 09:31 PM |
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ghrit
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pisces wrote: After about 250 shots my 17hmr barrel has built up a layer of carbon fouling, that can be seen when viewed from the breech, just after the leade.
Normally, this is when I use a wetted bronze brush to remove the fouling because it is widely attributed as being the cause of poor grouping due to bullet swaging.
However, my question is: If the bullet is swaged down by this restriction does the bullet expand further down the barrel so negating the swaging effect?
I don't think the slug will expand again. The swaging simply forces the bullet into the grooves and effectively seals the bore, rather than depending on obturation. I think (but do not know) that any leading after the leade is simply hot lead smeared off the tail of the slug (or off the sides of the ogive, if jacketed). For a guess, I'd say watch the groups, and don't bother getting all het up until they open up. Caveat: If your powder is the least bit hygroscopic, ignore that last, and clean every time out. 
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| Posted: Tue Jun 5th, 2007 01:37 PM |
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pisces
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Thanks for the info'.
Just received an e-mail from Anschutz saying much the same.
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| Posted: Thu Jun 7th, 2007 12:55 PM |
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72coupe
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I bought a new Kimber Model 82 Government from CMP. It has a similar problem in that it would lead up after about 60 shots to the point where the groups would open up to 2 feet or more. You could see a lump of lead build up 4 inches in front of the chamber. I used an Outers Foul Out III to remove it the 1st time but after that I used a worn out bore brush wrapped in a strand pulled from a copper pot scrubber. After a few thousand rounds (normal break in I guess) the problem dissappeared.
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| Posted: Thu Jun 7th, 2007 09:20 PM |
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ghrit
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I have not had that problem with my M-82. That said, I don't have 1000 rounds thru it yet, maybe not even half that. But DAMN it is accurate, even with WalMart low ball ammo.
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| Posted: Mon Jul 9th, 2007 05:20 PM |
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pisces
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72coupe wrote: I bought a new Kimber Model 82 Government from CMP. It has a similar problem in that it would lead up after about 60 shots to the point where the groups would open up to 2 feet or more. You could see a lump of lead build up 4 inches in front of the chamber. I used an Outers Foul Out III to remove it the 1st time but after that I used a worn out bore brush wrapped in a strand pulled from a copper pot scrubber. After a few thousand rounds (normal break in I guess) the problem dissappeared.
I am finding the same.
After 1,600 rounds the leade fouling is gradually becoming less of a problem
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| Posted: Mon Jul 9th, 2007 05:28 PM |
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72coupe
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Aggravating none the less!
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