Bad Primers or Carbon Ring?

[Straightshooter1]

Do you recheck your zero on your m500? I notice if I load 25...come back later and load more my zero changes having never move the scale.

Good question!

I have rechecked my zero from time to time and early on, when I first got the M500, was puzzled when I saw a change. And it took me a little while to figure out how to keep this from occurring and keep all measurements consistent. As I played with it, I was seeing what I would describe as a lot a play in the beam where it moved back and forth depending on my influence as I settled the pan in place. I would get different measurements depending on the position of the beam as I settled my pan to weigh it. If I make sure the beam is in the same starting position (at the magnetic dampening area) as as I rest the pan, the zero stays the same and I get the consistent measurements I look for.

I don't know if other balance scales, or which ones, have a similar issue . . . but my technique with my M500 has been working. I almost gave up until I found what works.

 

[fyrewall]

Sixgun,

I also noticed the primers were not excessively flattened, that would also be an indication of correct head space. Easy bolt lift has me somewhat surprised; I guess that tough Lapua brass contributed to that.

Good thread especially photos, thoughtful, thank you.

I think Remington 7 1/2's are frisky primers and I like them for 6.5X47 loads with H4350.

https://arxiv.org/ftp/arxiv/papers/1102/1102.1644.pdf

 

[Dusty Stevens]

We're only talking 10 degees and not even extreme 65 -75? I didnt even let them dwell in the chamber before taking the shot. Maybe my scale was lying..its only an old rcbs 505 although I do have a Chargemaster and an old lyman dps 1200. Dont use them much because I'm afraid they're gonna lie to me.

If they lie even 2 kernels do you think that will make a difference? Remember theres way more people out there winning matches with a chargemaster than there are on the internet telling you they dont work

 

[Straightshooter1]

If they lie even 2 kernels do you think that will make a difference?

I would think 2 kernels wouldn't make enough difference to be so concerned, especially if one has found a good node and is operating in the middle of it.

But, I'm a big believer in controlling and focusing on what I can control and not worry about what I can't control. And though 2 kernels may not make much of a difference, if I eliminate that issue as much as possible, then I can focus more on the other issues.

 

[Dgd6mm]

I see carbon ring mentioned as a possibility in the title of this thread. Have you borescoped it?

 

[searcher]

I used a ground squirrel load that I only used in cold weather at a certain shooting location that was the bomb. Then, after a few seasons, I checked my load at the local range in very hot weather. Went from no signs of pressure to two case separations in five shots. I'd say the temperature difference was more like 45 degrees. I personally would be a bit skeptical that 10 degree difference would go from no pressure to such primer damage, though it is entirely plausible. I would look for other ailments and which we sometimes overlook the most basic of things - you did mention it was new brass. You don't have a tight-neck chamber do you? Did you check the brass for trim length? I found that one of my custom rifles required shorter trim than would be considered "book". It was quite frustrating until I determined that was the culprit. The "few grains of powder", carbon ring appearing all at once, etc. don't sound like your problems. I believe the problem could be less powder case capacity in the new brass, too-long of brass length, change in powder lot, or other combined factors that, in conjunction with the air temperature change have combined to create this problem. Best to rule each out individually. Good Luck

 

[Sixgun]

I see carbon ring mentioned as a possibility in the title of this thread. Have you borescoped it?

No I havent..I dont have one. But i have been cleaning the throat after every hundred rounds. I really dont know how thick and fast it builds up so I'm getting it from the start.

 

[Nature Boy]

Had same problem with Varget and 223. Great load that shot extremely well in temperate conditions, but went to hell at 90*. Popping primers all over the place. Dropped it to the next lower node and viola! Perfectly tame.

I had this happen today. 95*

90 VLD, 24.2g Varget

 

[Texas10]

I was using 25.2 varget and popping primers with a 69 gr seated +.005. Dropped to 24.7 and hit paydirt.
If you're using 24.2 with a 90 gr, you must have a 223Rem Match chamber with the longer throat or you'd never get that much powder in the case. At 25.2 I was at max capacity with the 69 gr Lapua.

Anyway, I'd recommend you either bush the firing pin or drop the charge wt. or both.

 

[Nature Boy]

I was using 25.2 varget and popping primers with a 69 gr seated +.005. Dropped to 24.7 and hit paydirt.
If you're using 24.2 with a 90 gr, you must have a 223Rem Match chamber with the longer throat or you'd never get that much powder in the case. At 25.2 I was at max capacity with the 69 gr Lapua.

Anyway, I'd recommend you either bush the firing pin or drop the charge wt. or both.

Shilen match barrel with appropriate chamber for the heavy bullets

I’m think a the firing pin hole needs to be bushed