I cant figure out where my pressure is coming from.

barnesuser28

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i know i started a thread similar to this but i would like to add some more info to see if someone cant figure this out. Our savage 110 fcp hs 338 Lapua is shooting the 280 grain LRX with 82.4 grain of retumbo at 2635 fps with our newest lot. My first lot of retumbo i found that 84.4 grains of retumbo gave me same accuracy as the above load, but that laod was running 2730 fps. With my new lot (the 82.4 grain load) i obviously had to the drop the charge by 2 grains to get my accuracy back and get to where i wasnt getting ejector marks and heavy bolt lift. But my velocity dropped 100 fps?? Is this normal?

I am also concerned that i am getting ejector marks with only 84 grains of retumbo where most people are topping off at about 89 gr in the same rifle. I have no idea what could be causing the high pressure signs. I am perfectly fine with the accuracy but the high pressure from low charge weights are worrying me.

Thanks for any help on what the problem could be and how to correct it.
 

nddodd

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I've found over the years that this is just the nature of the beast, lots vary some by a lot some by very little. It's very annoying to find something your gun likes get used to it shooting good then your out of powder buy a new lot and it starts all over again and sometimes you don't get the same accuracy, speed nothing. Then find a diffirent powder and it takes previous powders spot then you guessed same thing again. Ok it's not quite that bad but it does happen. Same thing with lots of bullets as well at least with some I have used, base to ogive differences.

Anyway probably didn't help any but that's my .02


Nathan
 

MSLRHunter

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Can't help with the pressure, but I have a little advice on the powder lot frustration. Once you decide what powder you want to shoot buy in bulk. I just bought 8lbs of H4831sc for my 280AI and look forward to much shooting without worrying about powder.
 

BountyHunter

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1. Lot to lot variation.

2. Different throats in different guns. I have seen as much as 6 grains difference posted here on "max loads" on the 300 RUM in different guns.

3. Different primers can raise or lower pressures as much as 5000 PSI as documented by pressure gauges.

That is why internet loads need to taken with a grain of salt and worked up to very slowly in your gun.
 

barnesuser28

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I am going to revive this thread, i found out why my pressure would build up as i shot more and more rounds down range. I think the picture speaks for its self
 

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barnesuser28

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Don't believe I've ever seen a 1/4x20 thread in a barrel before
Sorry - couldn't resist that. :D
No kidding! It is like that as far as my borescope goes (its only about 6"). It will probably just be easier to screw a bartlein on it rather than send it back to savage. Although it would be cool to have it punched out to .408 and screw around with that...
 

royinidaho

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Riley,

Comical to say the least.

Who bored the barrel" Roto-Rooter.

I have a quick fix.....and I'm confident it would work.........

1. Shoot'r keeping pressure low for about a hundert rounds. The bore should shrink a couple of sizes. :D

2. Get some dies for a 338 Lap necked to .323 or so and run you brass through that.

Should solve your problem plus you'd have the u-neeo-kist rig at the range.:roll eyes:

Just say'n
 

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