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Belted Mag Pressure Indication Question

 
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  #1  
Old 06-17-2005, 08:42 PM
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Belted Mag Pressure Indication Question

I'm working up a load/s for a 338 Win Mag - factory REM 700. Am pushing for as much velocity that is reasonably practicable.

Powders being tested are RL-22/4831SC/7828/W760.

With non-belted cartridges my first indications of increasing pressure was a bit of stiffness when opening the bolt. When pressures got really up there the ejector slot/hole shined up a bit but that hardly ever happened in years of shooting.

With this rifle the first indication of pressure is the visible bright shiney extractor pin hole. Then when the bolt is opened it shines the case head a bit.

There are no other indications of pressure. Expansion ahead of the belt is mic'd as ok. Primer is not filling out to the edge of the primer pocket. Though I can get it there.

Any thoughts?????

Just trying to get some experience here.
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Old 06-18-2005, 03:32 PM
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Re: Belted Mag Pressure Indication Question

Some people say there are rifles more prone to marking the cases with the ejector without this necessarily meaning high pressure.

this has happened to me in my 7 mag rem 700 with rem cases... velocities were within reason although I got those markings.I am not saying you do not have to pay attention, but at least bear in mind the possibility of other reasons.
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Old 06-22-2005, 01:54 PM
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Re: Belted Mag Pressure Indication Question

I always get shiny spots on my .340wby, whether I'm using factory loads or reloads. I've had my smith look at it and its ok. I'd get your loads chronoed to make sure your not at high pressures. I think a sticky/stiff bolt is definate sign of high pressure. But many others have more experiece than me..
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Old 06-22-2005, 05:14 PM
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Re: Belted Mag Pressure Indication Question

[ QUOTE ]
I always get shiny spots on my .340wby, whether I'm using factory loads or reloads.

[/ QUOTE ]

My Win M70 300WM does the same thing and it looks like an ejector mark. Problem is that I don't have an ejector on the bolt - it has the claw extractor and a manual ejector. I think it just happens from closing the bolt - the case doesn't move, but the bolt does and leaves the shiny spot.
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Old 06-22-2005, 08:58 PM
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Re: Belted Mag Pressure Indication Question

I'm thinking that I'm just running a bit too much pressure. The chronograph says that I am at the top of the velocity range for the bullet. If I drop back 50 fps or so the shiney extractor pin hole disappears.

But now that summer came, hot days finally, I back off a full grain of RL-22 and get more velocity than with the extra grain. The temp. sensitivity is what I wanted to get away from but other powders don't give the better velocity and accuracy together as does RL-22.

Seems that every rifle is a bit different. Duh!
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Old 06-25-2005, 09:54 AM
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Re: Belted Mag Pressure Indication Question

If you are doing a good job of headspacing during resizing it seems to help these situations a little also. Loose primer pockets in 2-3 reloadings would also be a very good indicator. A while back I loaded some factory fired 300 weatherby and noticed that they all had extractor marks AND loose primer pockets. (With just the first firing of the rounds). I said to my friend let me guess--it was a hot day and the shells laid in the sun before firing. Found out later they were laying on the hood of the pickup in the hot sun. Just guessing but I'll bet he was running a good 70-75,000psi with that factory ammo. No one will ever accuse weatherby of loading conservative.
Chronoing your ammo would be a very good idea--sounds like you might be near the edge.
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