Are there pressure signs here?

[BourbonTrail]

These are old reloads I got from the previous owner, who got them from the previous owner.

That one “should” be well under pressure something like 75gr of IMR 4350. None of the others from that lot have swipe marks.

The two on the right are old Norma factory loads if I remember right (from ~1982). I plan to get a bullet puller for the rest and redo them when I can get new powder. However, I have to go through about 400rds...and would rather leave it in the safe.

 

[Inline6]

Forgive me, I at times take for granted that people know who I'll talking about.

GUNSMITHING SERVICES: STRIKER PIN BUSHING: M7, M700, M70(PF AND CRF), ACCURACY INTERNATIONAL, BERGARA, HOWA 1500, & RUGER RPR

A relatively frequent complaint with M700 and Accuracy International actions (and others) are cratered primers with factory made ammunition. The root cause of this is from excessive clearance between the striker and the hole through the bolt face. When fired, the primer cup flows into the void...

www.longriflesinc.com

 

[Pheroze]

This discussion has been extremely interesting, thank you. I keep going back over the comments and pictures and gain a little more insight each time.

This quote from the article @Inline6 posted seems to be consistent with the prevailing wisdom:

"This glitch in the design is further confirmed when inspecting the radius transition around the circumference of the primer. If it has not been hammered flat, it's unlikely that the ammunition is exceeding pressure limits."

Once again, reviewing things, the graph shows a plateau at cartridges # 11 & 12 of 3284 fps. This is plenty fast enough to basically hold dead on to 350 yards. I doubt I will ever shoot that far so this will achieve what I set out for. I will probably stare at this thread for the next 2 or 3 hours, but I think I will load up something between these two and check for consistency.

Best forum in this space/time continuum, that's for sure!

 

[Inline6]

These are old reloads I got from the previous owner, who got them from the previous owner.

That one “should” be well under pressure something like 75gr of IMR 4350. None of the others from that lot have swipe marks.

The two on the right are old Norma factory loads if I remember right (from ~1982). I plan to get a bullet puller for the rest and redo them when I can get new powder. However, I have to go through about 400rds...and would rather leave it in the safe.

Understand, just giving an opinion. When was the last time the copper fouling was removed from the bore? That could certainly help contribute to excess pressure. That round seems to do it rather quickly.

 

[BourbonTrail]

This discussion has been extremely interesting, thank you. I keep going back over the comments and pictures and gain a little more insight each time.

This quote from the article @Inline6 posted seems to be consistent with the prevailing wisdom:

"This glitch in the design is further confirmed when inspecting the radius transition around the circumference of the primer. If it has not been hammered flat, it's unlikely that the ammunition is exceeding pressure limits."

Once again, reviewing things, the graph shows a plateau at cartridges # 11 & 12 of 3284 fps. This is plenty fast enough to basically hold dead on to 350 yards. I doubt I will ever shoot that far so this will achieve what I set out for. I will probably stare at this thread for the next 2 or 3 hours, but I think I will load up something between these two and check for consistency.

Best forum in this space/time continuum, that's for sure!

After you get your powder charge nailed down, you can play with seating depth . You’ll be shooting loonies at a (Metric) grand in no time!

 

[BourbonTrail]

Understand, just giving an opinion. When was the last time the copper fouling was removed from the bore? That could certainly help contribute to excess pressure. That round seems to do it rather quickly.

I’ll check it out. I could start a whole new thread on diagnosing the issues with that rifle/ammo.

 

[Inline6]

I’ll check it out. I could start a whole new thread on diagnosing the issues with that rifle/ammo.

That was on me, did not see anything crazy just did like what the pictures show. Rather say something then see damage to you or your rifle. I'm sure you can start one and you will have a lot of good options on what to look at for sure.

 

[fourfive8]

I don’t see excessive pressure but probably up near comfortable max. The crater rim does indicate pin to bolt face clearance- not a big worry. Like some posts have alluded to, primer condition can also indicate false positives of excessive pressure, so primer condition should not be used as sole indicator of pressure. A little bit of extra headspace combined with an otherwise normal pressure load can cause a flattened primer- one of the false positives. Also, stiff bolt lift is a gross indicator of high pressure and should not be ignored.

 

[Pheroze]

I don’t see excessive pressure but probably up near comfortable max. The crater rim does indicate pin to bolt face clearance- not a big worry. Like some posts have alluded to, primer condition can also indicate false positives of excessive pressure, so primer condition should not be used as sole indicator of pressure. A little bit of extra headspace combined with an otherwise normal pressure load can cause a flattened primer- one of the false positives. Also, stiff bolt lift is a gross indicator of high pressure and should not be ignored.

Reading pressure signs seemed to be as much an art as it is a science! But, the more I understand about the mechanics of it the more it just makes sense.

 

[IvW]

I see no pressure sighs.
Velocity is high.
How how you wanna go?

 

[Pheroze]

I see no pressure sighs.
Velocity is high.
How how you wanna go?

I am going to try a load at about 3280 as there seems to be a plateau there I have no need to push it.