New Rifle-High pressure, low velocity

Shaidon · #1 07-24-2009, 01:29 AM

Hey guys, I need some help. Just got my rifle from the smith. Its a 338 edge, stiller predator action with a rock creek barrel. I am shooting the standard load for this rifle, 92 gr H-1000, 300 SMK, CCI 250, and rem brass. I had the smith turn down the reamer a small amount, not sure how much, since I am partial neck turning the brass (removing approx. 70%) and didn't want too sloppy of a chamber. I tried an un-turned load and it is too tight to chamber. It will feed all the way into the chamber but I cant close the bolt. My turned rounds chamber just fine. The problem I am seeing is obvious extractor marks but the bolt does not have any noticeable stick to it. My velocities are right about 2775 on average. It seems to me there is a lot of pressure for this load with that velocity. I took some of my spent cases (not resized or anything after firing) and tried to slide a bullet in by hand. There is quite a bit of pressure but they will slide in with effort. It seems to me this is too much neck tension for fired brass. Could the tighter neck in the chamber be causing the high pressure problem or could it be something else like the barrel being new and needing to break in. Any help would be great. THANKS

Joel Russo · #2 07-24-2009, 05:30 AM

You need to know what your chamber neck dimensions are! Call the guy that chambered it, and ask him. After you find out what it is, you can then turn your necks to give you the proper clearance when you chamber a round. Usually .003"- .004". If you have a bushing die, you can then adjust neck tension by changing bushings.
Then do your load development by measuring case stretch over a virgin piece of brass. This will tell you when you are approaching your max load way before you get to the "heavy bolt lift" or extractor marks.
Standard loads are not standard in all rifles, you may have an extremely tight bore.. thus coming upon max load before the advertised max load.
You don't mention where you are seating the bullet in relation to the lands. Keep in mind that the closer to the lands you go, the more pressure you will encounter.

Shaidon · #3 07-24-2009, 01:08 PM

Thanks for the info Joel. Just talked to the gunsmith and the chamber neck dimension is .367, and my turned loaded rounds are at .363 so that's just where you said it should be. I guess another issue could be the virgin brass, he said the headspace dimensions on the virgin cases did have some inconsistencies. It seems that not all of the cases have extractor marks so possibly the ones that do are the ones with the shorter headspace dimensions and they are slamming back into the bolt face unlike the ones that are a little bit longer. I guess I may be jumping the gun a little bit and need to get the barrel a bit more broke in before getting worried. Thanks again and if there are any other issues you could think of, please let me know.

Shaidon · #4 07-24-2009, 01:11 PM

oops, forgot one thing. I am about .018 of the lands so that seems to be good.

Joel Russo · #5 07-24-2009, 04:42 PM

You're moving in the right direction.
Unfortunately when working with Remington brass, you are going to have variances.
When you get it all sorted out, let us know what the final results are.

Hired Gun · #6 07-25-2009, 08:17 PM

I was thinking 2800 is about all the Edge was doing at max pressure in a 30" barrel and some special throat work + .050" freebore. It also sounds like you need to take a bit more off your necks if it still takes some pressure to slip a bullet into a fired brass. They should slip in with almost no effort. Otherwise your results seem to be what I would expect. I remember Carlock metioning formerly safe loads of H1000 were now over pressure with current lots of powder and he has since recommmended everyone back down and work up again. Doesn't anyone else remember that.

Joel Russo · #7 07-25-2009, 08:39 PM

Quote:

Originally Posted by Joel Russo

Then do your load development by measuring case stretch over a virgin piece of brass. This will tell you when you are approaching your max load way before you get to the "heavy bolt lift" or extractor marks.
Standard loads are not standard in all rifles,.

That's why I suggested he do the above.