7mm Rem Mag Brass Life and barrel life

[deadly50bmg]

Hey guys, I have a R700 PSS that was shooting freakin' crazy accurate for a factory gun for the past year. 3/4 moa and under easily. After about 1000 rounds I am noticing my groups are going up. Just did 100 rounds at 500 yards and shot consistent 5" groups the whole time. I know thats about par for these guns, however, I was previously getting 3-4" groups at that range. Could this be caused by the brass being on its 10th reload? I am not showing any cracked necks. Also, how many accurate rounds should I expect from this factory barrel?

Thanks guys for you help

 

[Preacher]

10 reloads will certainly harden the brass enough to enlarge your groups..
I never let mine go more than 5 before they are annealed again..........
You also probably have moved the throat forward with 1000 rounds, and may need to move the bullet further into the rifling to bring back the accuracy....
If it shoots that good I would have the barrel set back and start all over again if all else fails...

 

[wnroscoe]

I've shot out two 7mmRM's and am on my third. The first was a factory 700BDL, the second a Shilen Barreled custom. Accuracy with the 7mmRM is crazy good but, only for 700-900 rounds in a factory offering and 900-1000 in a custom in my experience. You can chase the throat for a little while but, it will out run you. You might try new brass first, 10 firings is more than I get. My accuracy seems to fall off after 4 firings, after 6, their toast. Also, re-check your seating depth, a friend of mine had a 7mmRM that started acting up. When I checked his seating depth to throat, the throat had moved .015" out. We re-set his seat die and all was good again.

 

[deadly50bmg]

What is a good way to know where my throat is at? I shoot Molly'd 168gn MK's so when I chamber one then pull it out I can see where the molly was rubbed off to expose the copper jacket showing the lands marks. Some rounds seem to be a whole lot tighter to close the bolt than others. Also, when I fire and extract the casing I have had several that are extremely hard to pull the bolt back...to the point where I have had to get a rubber mallet and tap the bolt handle to free it up. Loads are just hot enough to show a shiny plunger mark but primer pockets havent really loosened up much so I figure my loads aren't too hot. Should I set the bullet out more? Does it sound like I'm running too hot?

 

[Preacher]

Any time you need a rubber hammer to open a bolt, your either into a high pressure area, or you need to full length size your cases to fit perfectly in your chamber.....
If your Molly'd bullets show rifling marks when you take them out there is no need to push em in any farther...

 

[Spotcheck_Billy]

It's been my experience that any time I see a "shiny plunger mark" the load is already too hot. I'm surprised that you're getting ten reload on your brass with that kind of pressure.

 

[deadly50bmg]

Thanks for the help guys, I am currently using RCBS Competition FL dies. It boggles my mind as well that I have not split any necks yet. I think I will try some new brass just to see how that does as well as lower my load a little.

Thanks again

 

[wnroscoe]

If you use a case with .001" neck tension you can soft seat a bullet long then place it into the chamber and close the bolt on it. You will be using the bolt to finish seating your bullet, that'll give you a good idea as to where you’re at. Using this method, I'll seat the bullet about .005" further into the case and start load development at that point. You can also use the stoney point tool to measure your throat and its movement/erosion. It also sounds like you may not be sizing your brass enough, you only want to bump the shoulder about .0015" to .002" though, just enough so the bolt closes smoothly, no more. Try new brass and keep the round count the same on all pieces.