Is this a pressure sign? (double rifle)

[A Rosenth]

Been doing some load development with my new 500 NE DR. After talking to Ken Owen I decided to try some IMR 3031 and work up from a starting point of 77 gr with a bit of open cell foam for a filler. With 77 grains my velocity was 1872 ft/s average. With 78 grains my velocity was 1890 ft/s average. Based on the point of impact with 78 grains I could tell I was getting close to where I wanted to be in terms of regulation. Went out and shot 2 rounds with 79 grains and got speeds of 1935 and 1916. Unfortunately I think I made a bad shot on the first one so I didn't really get a good idea about the regulation, but when I picked up the brass I noticed these little marks on the primers. They are small but noticeable and they line up with the holes on the action next to the firing pins. I checked some other used brass and did not see these same marks. To me this looks similar to ejector marks on brass in a bolt gun, when the brass actually flows into the hole where the ejector is recessed, but I'm not sure that primer material would actually flow in that same way. Curious to know if this is a known sign of pressure in a DR, or if there's some other explanation for it. Obviously I don't want to go increasing powder charges until I know what's going on.

Thanks

 

[matt85]

I'm no expert but the pressure does look a touch high on those. If it were me, I would go to a different powder or bullet.

 

[One Day...]

Yes, I believe that you have excessive pressure indicators in these two shells.

To me, what you call "these little marks" (primer reflow) are not the only telling signs. Flattened primers with sharps edges are generally considered the instant visual clue that you are pushing things.

 

[Rare Breed]

Been doing some load development with my new 500 NE DR. After talking to Ken Owen I decided to try some IMR 3031 and work up from a starting point of 77 gr with a bit of open cell foam for a filler. With 77 grains my velocity was 1872 ft/s average. With 78 grains my velocity was 1890 ft/s average. Based on the point of impact with 78 grains I could tell I was getting close to where I wanted to be in terms of regulation. Went out and shot 2 rounds with 79 grains and got speeds of 1935 and 1916. Unfortunately I think I made a bad shot on the first one so I didn't really get a good idea about the regulation, but when I picked up the brass I noticed these little marks on the primers. They are small but noticeable and they line up with the holes on the action next to the firing pins. I checked some other used brass and did not see these same marks. To me this looks similar to ejector marks on brass in a bolt gun, when the brass actually flows into the hole where the ejector is recessed, but I'm not sure that primer material would actually flow in that same way. Curious to know if this is a known sign of pressure in a DR, or if there's some other explanation for it. Obviously I don't want to go increasing powder charges until I know what's going on.

Thanks

View attachment 620056

I worked with Ken on my 500 NE with IMR 3031 and found 80 grains gave me 1.5 inch regulation at 50 yards

 

[Mike B.]

Factory loads in my double do it. All of the lower pic of factory brass is once fired Hornady DGS. Also did it on lower velocity 1900ish feet per second hand loads I’ve been messing with trying to see if CEB bullets will regulate ok. I started lower with 79.5gr of N165 pushing their 400gr solid and up to 83.5gr which got me to about 1990fps. About the same as factory. I don’t see much of a difference in any of the actual handload casings as even the lowest pressure ones have some indentations in the primers although I did start to see a slight amount of flattening. First is the factory and second is my hand loads.

 

[A Rosenth]

Very interesting re: the factory loads. I loaded up some H4350 (99.5 gr - basically just above a starting load) to test out today to see if I get the same thing. May also take out some factory loaded Federal to test as well. I think I'll also call Ken today and see if I can get his thoughts.

 

[raamw]

To me the initial sign of excessive pressure is flattened primers meaning a new seated primer has rounded edges, a primer that fills in these rounded edges so it fills the primer slot in the casing is a sign to back down the pressure, wait till the out side temperature get hot pressure goes up. To me the next level in pressure sign it the primer starting to form around the firing pin and creeping into the bolt head I refer that as cratering, next step would be a burn out of the primer, now in a bolt action there is a pressure relief in the action near the lock up but not the case in single of double barrel rifles. The picture above shows signs of cratering on the firing pin and somewhat flattened primer

Interesting site on this subject https://www.primalrights.com/library/articles/understanding-pressure

 

[A Rosenth]

Thanks for all the replies. I looked at a bunch of fired and unfired primers, and some primers that were in factory loads. I know the picture kind of looks like the primer may be flattened, but under a hand lens they actually look to have the same curvature as unfired primers, so I don't think that's an issue. Also, the primers from factory Federal loads also have (smaller) similar marks.

I also called and talked to Ken Owen about this, and sent him some pictures of my primers and fired brass. He said that this doesn't look like an over pressure situation. Pressure might be on the higher end of things, but based on the amount of powder, the velocity I'm getting, and the appearance of the brass and primers he wasn't concerned about it.

I'm going to try some H4350 today and see how that goes - I've shot some of it already and I know that with bullets going ~2100 fps (only 101 grains of powder) by bullets are crossing, so need to bring that speed down.

Hope this info is helpful for someone - Ken seems like a wealth of knowledge and I'm glad I've been able to talk to him about the 3031 powder and these primers/cases!