excessive pressure ?

12 April 2002, 18:26

<Alleycat>

Not necessarily. Could be a weak striker spring, pitting around the firing pin hole in the bolt, firing pin fits loosely thru firing pin hole. The pitting or loose fitting firing allows the primer to crater into the pitting or the gap around the poor fitting firing pin. With the weak striker spring the striker does not stay forward properly. The weak spring allows it to move rearward to soon so the primer craters into the firing pin hole.
More info. would help. What type of ammo out of what type of firearm?

12 April 2002, 19:02

<MAKATAK>

It all depends on a lot of factors. You didn't give much background info.

If this is factory ammo I would guess a weak firing pin spring or a slightly oversized firing pin hole, depending, again, on all the surrounding factors.

If this is something you cooked up or your buddy gave you to try, I would STOP screwing around, you may be an accident waiting to happen. I have a few rifles that do that to primers with several reloads and several brands of primers. It doesn't concern me in the least because I know the loads are safe and nowhere near the twilight zone.

If the primer isn't flattened out around the edge or falls out when you open the bolt and you don't have to kick the bolt open and you get more than one reload per case, you're probably OK. That was just hyperbole.

It may be nothing more than an oversized firing pin hole. If you are concerned, my advice is, take it to a good gunsmith and let him check it out. These forums are a good place for information but you really don't know who is answering or what their level of expertise is. Let an expert in the trade answer your questions in their shop.

13 April 2002, 04:41

<cohoyo>

it's probably pressure because i'm shooting loads that are at the listed max in the reloading manual so I'll pull the bullets and drop the charge. i'm shooting a .358 norma mag with 250 gr barnes x bullets. the load is 66 grains of rl 15. the bolt opens normal and the primers look fine except for that ring. I worked up to 65 grains with no problems so I went to 66 and got the ring. I'm thinking it may have something to do with the outside temperature, last week it was 32 degrees when i shot 65 gr and yesterday it was 50. I any event i'll drop my load again and see if the ring goes away.

13 April 2002, 04:52

parshal

quote:
Originally posted by MAKATAK:
If the primer isn't flattened out around the edge or falls out when you open the bolt and you don't have to kick the bolt open and you get more than one reload per case, you're probably OK. B]

I've been reloading for my .264 and I've tried six powders so far. On every one, the primers are flat. I'm still slightly short of the published velocities and I'm a few grains higher than the maximum depending the manual you look at (I have nosler, sierra and speer plus checked the powder manufacturers). Sometimes I get a small mark on the case head from hitting the extractor pin (rem. 700) but I've backed off those that actually smear. I've had some experienced reloaders look at the cases as they come out of the rifle and all tell me I could actually go higher. I seem to get the best accuracy with these larger loads and all I really see is the flat primer.

My question is, if all I'm seeing are flat primers and my rifle is accurate with the loads, is that to high for my rifle?

13 April 2002, 05:18

Stonecreek

Parshal: The "flatness" of the fired primers may have more to do with the headspace than with pressure. If some significant amount (even a safe amount) of headspace exists, upon firing the primer will back out of the pocket until it is tight against the bolt face. As pressure builds, the case stretches and the case head catches up to the backed-out primer. When this happens, the edges of the primer spread more than they would have if headspace had been fairly tight, making them appear flatter. This appearance is similar to that which you might see with excessive pressure and tight headspace.

Chambers for belted magnum cases are infamous for sloppy headspace. Try neck-sizing only some cases fired in your chamber and see if your primers come out less "flattened". This will tell you whether you are dealing with loose headspace or high pressure.

13 April 2002, 08:09

parshal

quote:
Originally posted by Stonecreek:
Parshal: The "flatness" of the fired primers may have more to do with the headspace than with pressure. If some significant amount (even a safe amount) of headspace exists, upon firing the primer will back out of the pocket until it is tight against the bolt face. As pressure builds, the case stretches and the case head catches up to the backed-out primer. When this happens, the edges of the primer spread more than they would have if headspace had been fairly tight, making them appear flatter. This appearance is similar to that which you might see with excessive pressure and tight headspace.
Chambers for belted magnum cases are infamous for sloppy headspace. Try neck-sizing only some cases fired in your chamber and see if your primers come out less "flattened". This will tell you whether you are dealing with loose headspace or high pressure.

Thanks for the information, I'll be reloading the once-fired, neck-sized brass here in the next range session or two. I've been using new brass until it's all fired.

Thanks again.

14 April 2002, 18:56

Pecos41

Cohoyo, you describe what I call "primer splash" which CAN be caused by some of the items mentioned, i.e. weak firing pin spring etc. However, if this is associated with really flattened primers, I would take it as a sign of mucho pressure and beware.

When you deprime these cases with this "splashed primer"...look at the fired primers carefully. You may also discover in addition to the "splash" that the base of the primer has also started to flow outwards towards the casehead. Now you are looking at a primer with the "splash" and also the outward flow on the head so that the once cupped shape primer looks a bit like a mushroom with a pucker on top. Hope you can visualize what I'm describing. If not, got look at the primers and you will probably see it.

The snag here is some manufacturers use a tougher metal in their primer cups and brand "A" may show pressure signs before brand "B" primers.

The main point is take ALL these little warning signs seriously and work upwards very cautiously. The next warning may not be quite so subtle. I think more times than not, pushing loads to the razors edge is counter-productive and has no real value in accuracy or bullet effectiveness in hunting. It's sort of like always revving an engine up to the red line each time before shifting. Good way to blow an engine and NOT the most efficient way of driving or reloading. Most reloaders start out pursuing this last possible fps velocity, but the old timers usually grow out of it. Achieving the absolute maximum velocity is NOT the ultimate goal of reloading. The REAL GOAL, in my humble opion, is to simply find which bullet/powder combination works best in YOUR individual rifle or pistol. If that load just happens to be 200 fps below factory or someone else's best load...so what? Shoot it. If your gun is happy, it will likely make YOU happy. Regards.