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Reloading Techniques For Reloading


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Flattened Primers...

 
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  #8  
Old 07-28-2013, 10:15 PM
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Join Date: Oct 2008
Location: Alabama
Posts: 5,287
Re: Flattened Primers...

Quote:
Originally Posted by Lefty7mmstw View Post
Muddy, I think you've gotta step back a bit more than that on your 7stw if she's sticky. Here's a pressure graph you've seen before from my old sendero 7stw; the win 150 grain load hit over 70 Kpsi peak and she didn't have heavy bolt lift. I'd go 3 to 5 percent down on charge as your pressure should fall twice as fast as the charge drop.
How does one go about measuring chamber pressure? I have always wondered that...All these guys know how much kpsi their loads produce, but I guess I have no idea how they measure that stuff.

I was reading on another thread, and a guy was having the sticky bolt issue with a 300 WM, sounded alot like mine, but he fixed his very quickly and simply, just by backing off the lands a couple thou. He said the bullet on the lands was causing some funky excess pressure spikes and causing his bolt to stick. He said he backed them off a couple thousandths, had his chamber polished, and now he has no issues at all. I guess I'll try his fix to see if it doesn't fix it first. Then I might have to get my chamber polished by my smith. Since it keeps leaving rough drag marks about 1/8" above the belt, even on brass on its second load...Which shouldn't be happening. Obviously I need to have my smith scope the bore anyway. Just want to make sure the throats still in great shape. Should be, since I should only be about 1/2 way theough my barrel's lifespan.

Found out the new (to me) 700 .338 WinMag won't hit the broad side of a barn. Cold-bore, shoots great. Second shot, close. Third shot, God's knows if it's gonna shoot high, low, left, or right, or any combo of those...

Looks like a good candidate for another 7STW...Being it's a Magnum LA receiver.

OR, I'm gonna make it a lightweight .257 Wby Mag for whitetail hunting. Haven't decided...
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Quote:
Originally Posted by WildRose View Post
The 284 is to the STW what a tricycle is to a Ninja.
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  #9  
Old 07-29-2013, 09:01 AM
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Join Date: May 2012
Location: N.D.
Posts: 2,791
Re: Flattened Primers...

Quote:
Originally Posted by MudRunner2005 View Post
How does one go about measuring chamber pressure? I have always wondered that...All these guys know how much kpsi their loads produce, but I guess I have no idea how they measure that stuff.

I was reading on another thread, and a guy was having the sticky bolt issue with a 300 WM, sounded alot like mine, but he fixed his very quickly and simply, just by backing off the lands a couple thou. He said the bullet on the lands was causing some funky excess pressure spikes and causing his bolt to stick. He said he backed them off a couple thousandths, had his chamber polished, and now he has no issues at all. I guess I'll try his fix to see if it doesn't fix it first. Then I might have to get my chamber polished by my smith. Since it keeps leaving rough drag marks about 1/8" above the belt, even on brass on its second load...Which shouldn't be happening. Obviously I need to have my smith scope the bore anyway. Just want to make sure the throats still in great shape. Should be, since I should only be about 1/2 way theough my barrel's lifespan.

Found out the new (to me) 700 .338 WinMag won't hit the broad side of a barn. Cold-bore, shoots great. Second shot, close. Third shot, God's knows if it's gonna shoot high, low, left, or right, or any combo of those...

Looks like a good candidate for another 7STW...Being it's a Magnum LA receiver.

OR, I'm gonna make it a lightweight .257 Wby Mag for whitetail hunting. Haven't decided...
The easiest way to measure pressure is to get a strain gauge system. The one we were using the gauge was simply glued to the outside of the chamber and measurements were taken for steel thickness, etc.. You should get within a couple of thousand psi. of actual with one of these if you are careful. The only other way I know of is with pressure barrels with chambers side drilled to accept a pressure gauge. Not very portable; mainly for lab use.

The biggest thing people forget about when seating out to the rifling is the bullet won't have a run at the rifling and may essentially "stall" as it hits the rifling, causing the pressure to go up to overcome the drag. This is more trouble with mono. type bullets but can happen with others too. I let 'em run a bit if I can.
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