Over pressure sign???

[FROGO207]

As far as loads go I make accuracy within safe pressures my number one priority. Lowering pressure may help but if accuracy goes to heck then I would do something else. This is not a problem if you are not peircing primers and can eject rounds normally assuming it also happens with factory ammo. You could get factory/gunsmith work done on the bolt or leave it as is and just inspect it regularly.

 

[2ndtimer]

I’ll get some factory ammo and try it out.

If the pin hole is the issue, would this be an issue that I would need to fix? Would it be fine as long as I back down the load until the primers dont show the overflow ring?

As I stated previously on my Remington, I have had it cratering primers for about 20 years, thousands of rounds both factory and handloads. So you can use the lighter load if you prefer, have a gunsmith see if the firing pin is undersized or the bolt needs to have the firing pin aperture replaced, or you could just shoot the most accurate load and not worry about it. If you start seeing pierced primers, then I would have the rifle looked at. YMMV.

 

[Blue68f100]

I’ll get some factory ammo and try it out.

If the pin hole is the issue, would this be an issue that I would need to fix? Would it be fine as long as I back down the load until the primers dont show the overflow ring?

As long as your not piercing/blowing primers you will not have a problem. Once you pierce one the FP gets damaged and it will accour more often. Gunsmith charges for bushing a bolt is around $100. I had a AR bolt that had a 0.004" clearance and it would pierce even the heavy Mil primers. I ended up replacing the bolt after the mfg sent me a replacement that was bad too. I have since repaired the bolt with a bushing so I have a spare if needed.

 

[jmr40]

Looks like 3 different brands of brass and 2 different primers. That makes it hard to pinpoint any issues.

While not perfect this is why I use a chronograph when developing loads. The loading manuals give me a pretty good idea of what velocity to expect with a max load. If I'm getting close to that velocity, it's time to stop adding more powder even if I'm well below the max powder charge in the load manual.

While rare I once had a situation where 3000 fps was the expected velocity with a max load. I was at 2950 with a powder charge 2 gr below max. I already had some loads with 1/2 gr more powder loaded in them: still 1 1/2 gr below max. But when I fired them I was well over 3000 fps and obviously an over pressure load. But other than more recoil there were no traditional over pressure signs.

I decided 2950 fps was close enough.

 

[zeke]

imo, reading primers does not tell you if you are over max pressure, unless something extreme happens like blowing out/piercing a primer. Even then there are conditions that could make that happen besides overpressure. imo, reading primers can indicate increasing pressure, given that everything else stays the same. Am not experienced with 300 mag, but am always relying on a chrono when working up loads. Someone already indicated brands of brass may matter in load work up. Especially when comparing your velocities with the velocities manual indicate. Indicating the barrel length and recorded velocities may help with the answers given.

 

[MEHavey]

poor firing pin fit to the firing pin hole

^^^^^ THIS ^^^^^
Not overpressure per se