New barrel velocity decreasing

whirlwindjml

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Aug 23, 2009
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Rathdrum Idaho
It can definitely raise pressure but when barrels fowl theres more friction hence less velocity. Copper will adhere to Copper so more friction.
Mabey ill shoot at 59 grains for a bit with frequent cleaning and document the speeds after cleaning it each time....i hope the range opens soon its a looong drive to my forest spot that still snowed roads. Thanks
 

milo-2

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May 1, 2011
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Gillette, Wy
It can definitely raise pressure but when barrels fowl theres more friction hence less velocity. Copper will adhere to Copper so more friction.
I agree with this, the muzzle end of your barrel is getting fouled. If you have copper fouling, most likely carbon too, building up in the muzzle end of the barrel. This doesn't automatically mean the end of the barrel is where the problem is, just where buildup is occurring.
I think if you kept shooting w/o cleaning, you would get false pressure signs. Some powders are known to foul the end of the barrel, also too light of charge can foul a barrel.
Keep us posted.
A 49.00 teslong borescope may be a great tool to own right now.
 
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can1010

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Feb 27, 2012
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721
your magnetospeed slipped. measure from muzzle to the mount and record the distance if it slips even the slightest amount it will change velocity. have seen this happen so many times at the range. I started putting a small piece of rubber or the extra spacers under the mount strap on the top of the barrel and it has helped the problem considerably
 

whirlwindjml

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Aug 23, 2009
Messages
279
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Rathdrum Idaho
your magnetospeed slipped. measure from muzzle to the mount and record the distance if it slips even the slightest amount it will change velocity. have seen this happen so many times at the range. I started putting a small piece of rubber or the extra spacers under the mount strap on the top of the barrel and it has helped the problem considerably
I has it moved on the first outing but i check it constantly. It didnt move. My pencil barrels have been a problem but it stays put on my bull Barrel and heavy barrel.
 
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Shadowwalker

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May 23, 2018
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GiLMER TX
I has it move on the first outing but i checkbit constantly. It didnt move.
I have had this problem also with the thing moving.
Also get rid of the Sweets it turns to nitric acid at 400 degrees ( Read Vaughn's book) and you got at least 2500 per shot. I know about this as I worked for a premier barrel maker for years and we just loved seeing Sweets used. We did more business because of this than anything else.
 

whirlwindjml

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Aug 23, 2009
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Location
Rathdrum Idaho
I have had this problem also with the thing moving.
Also get rid of the Sweets it turns to nitric acid at 400 degrees ( Read Vaughn's book) and you got at least 2500 per shot. I know about this as I worked for a premier barrel maker for years and we just loved seeing Sweets used. We did more business because of this than anything else.
From people leaving it in while shooting? I have about 30 cleaning products. Honesty...i rotate them. I cant see how the sweet would be a problem if ya clean it out?
 

vancewalker007

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Mar 30, 2013
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285
I have 28 or so rounds down the pipe in a factory 6.5prc savage tactical. First couple shots hovered 2950....by the end of those first 12 shots it was 2922 (magneto speed)57.7 h1000

Pressure wasnt a problem at all so i bumped to 58.4 first 2 were back up to 2950. By the time i was finished with 16 rounds (pre filled at home/bullets seated at range) the gun had stepped down and hoovered at 2895ish.

I am seated very close to the lands. i have usually had bullets speed up as barrels get shot for the first while. So is this slow down mabey from the throat being worn in and reducing the pressure a bit?View attachment 186391

Its shooting great with no indication of pressure yet. The last slower groups were 1/2 moa ish but now i gotta get another bump in pixie dust to get it tword the 2950 im hopeing for.
This is not about your speed issue but you might want to shoot a powder ladder through the 59s if your using a 140-143gr bullet. You likely have some more head room there in velocity. Not that things are equal but my PRC is in the 60-60.5 with H1000 and the 140-143gr bullets at around 15-20 off.
 

bbelgians

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Joined
Dec 31, 2008
Messages
21
I have a savage GRS in 6mm Creedmoor, and I have noticed that after I clean the barrel I will have pressure signs, but after 5 or so shot all signs of pressure signs will disappear. All I can figure is that the tool marks increase pressure until a copper smooths the barrel out.
 

whirlwindjml

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Joined
Aug 23, 2009
Messages
279
Location
Rathdrum Idaho
This is not about your speed issue but you might want to shoot a powder ladder through the 59s if your using a 140-143gr bullet. You likely have some more head room there in velocity. Not that things are equal but my PRC is in the 60-60.5 with H1000 and the 140-143gr bullets at around 15-20 off.
Ok. I may do that.. So far i have 500 147s but the 143 have worked good on quite a few elk so they are on the table as well.
 

whirlwindjml

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Joined
Aug 23, 2009
Messages
279
Location
Rathdrum Idaho
I have a savage GRS in 6mm Creedmoor, and I have noticed that after I clean the barrel I will have pressure signs, but after 5 or so shot all signs of pressure signs will disappear. All I can figure is that the tool marks increase pressure until a copper smooths the barrel out.
How many shots through it? (approximation)
 

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