DoneNOut
Well-Known Member
The ball bearing thing works. Only if a HARDENED steel bolt and chrome bearing are used. A plain stainless bolt won't work. I tried it without hardened bolt and got nowhere.
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Hidden Pressure Reading: A Method
- Thread starter DoneNOut
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I wonder if the primer pockets are in expansion outside of specs, what is the web measurement for the potential of case head separation? I bet there is a strong correlation. Now something to measure! You did it again to me!
DoneNOut
Well-Known Member
To add to the equation...I only do the ball bearing on coveted Lapua brass. Lapua brass has that extra primer pocket liner to them.
@Muddyboots - Edit to add, I had PPU brass pockets open up without any other issues. I found my primers in the ammo box as some of the cartridges didn't go bang! LOL
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No this is wrong. Case head seperation comes when the shoulder is pushed back, leading to brass stretching somewhere in front of the web to mid-level in the case.
ON really hot loads, the case head would expand leading to hard bolt lift, deformed case heads, and possibly loose primer pockets.
Oil or solvent in the chamber can leade to ejector pin hole swipes also, case head deformation. After cleaning, be sure to clean and dry your chamber with a swab with denatured alcohol, cigarette light fuel, Acetone, or engine starter.
A big A-Men to that !
MagnumManiac
Well-Known Member
I have to clear something up here, actions are built to withstand 3 or 4 times the amount of chamber pressure, some, like the Weatherby Mark V, are even stronger than this. The nominal rate of destruction is in excess of 200,000psi for CM actions or above, and a little less for SS actions of 416 material, this varies of course.
Now, actions are built to be used for myriad of cartridges, therefore the reason behind having a yield strength of 200,000psi or more.
Another factor regarding pressure in a cartridge is this, if webs are thin, such as Norma brass, primer pockets will expand far sooner and easier than cases with thick webs, like Winchester older brass and Lapua. There is no way around this.
When I tested cases to blown primers over the Pressure Trace, Norma was the lowest, then Federal, then Hornady, then Bonanza (which I think are Hornady), then S&B, then Remington, then Winchester and Lapua, all with LR primers, those same cases were tested with SR primers (those available) and the results were flabbergasting, a SR primed case will take half again more pressure before primers blow and the pocket deforms, which is why I switched to SR primers in every case that had the option up to 308. Now, when you take a .473" case head, replace a .210" hole with a .175" and you have far more surface area for the pressure to expand…which is a very good thing.
The same is true with .375" case heads, but they are smaller anyway.
Cheers.
Now, actions are built to be used for myriad of cartridges, therefore the reason behind having a yield strength of 200,000psi or more.
Another factor regarding pressure in a cartridge is this, if webs are thin, such as Norma brass, primer pockets will expand far sooner and easier than cases with thick webs, like Winchester older brass and Lapua. There is no way around this.
When I tested cases to blown primers over the Pressure Trace, Norma was the lowest, then Federal, then Hornady, then Bonanza (which I think are Hornady), then S&B, then Remington, then Winchester and Lapua, all with LR primers, those same cases were tested with SR primers (those available) and the results were flabbergasting, a SR primed case will take half again more pressure before primers blow and the pocket deforms, which is why I switched to SR primers in every case that had the option up to 308. Now, when you take a .473" case head, replace a .210" hole with a .175" and you have far more surface area for the pressure to expand…which is a very good thing.
The same is true with .375" case heads, but they are smaller anyway.
Cheers.
MagnumManiac
Well-Known Member
Have to disagree, primer appearance alone is a very poor indication of pressure. Just like brass internal structure, brass cups in primers also vary quite a bit. I tested actual known pressure loads, those below max by 5,000psi just to observe primer appearance by brand, the results were very interesting. Some would show cratering just as max was reached, not over, some showed flattened primers, Federal were the worst, some showed nothing, CCI were good for this until max was well surpassed. Remington primers were funky, they appear to vary in hardness the most, some not showing anything while others pierced for no reason.
I never go by primer appearance, have been fooled too many times, but, if a primer is showing cratering when the rifle normally doesn't do that, that is the only time I take notice of that. Flattened primers are often the primer hardness, but if there are OTHER signs of excess pressure, stiff bolt lift, extractor marks or loose primers, then the load is too hot.
Cheers.
I pay little attention to primers, also Magnum. You may have misunderstood my A Men. I take notice that as the pressure goes up, the cups first loose their roundness on the edges, then start to get a little more defined squareness, then start to fill out a flat on top. They may take on the surface finish of the bolt face on the top end. where flat as a pancake.
Some primer flow into the firing pinhole is an indication of an oversize firing pin hole, only. I had a 257 Weatherby in a model 70 custom that showed extremes in primer flow and I just ignored it, never blanking a primer with R#22.
Some primer flow into the firing pinhole is an indication of an oversize firing pin hole, only. I had a 257 Weatherby in a model 70 custom that showed extremes in primer flow and I just ignored it, never blanking a primer with R#22.
MagnumManiac
Well-Known Member
Totally agree, my bad. Boy, stepped on tongue.
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Mike Matteson
Well-Known Member
I use Blue Dot in my 12 gauge, 2 3/4". 1 3/8 oz loads. I just change the shot size for whatever I hunted. From dove to Geese. Until they changed to steel shot. Quite hunting Ducks. A friend of mind and I woud go to Niland CA for hunt dove opening morning.
I used a 24" ImpC with that load. I could reach 50 yds no problem. People would use there 1oz loads and try and reach them at those ranges. I had to laugh at them. My friend would get may and ask me to put on my 34" barrel. Then I could reach 90yds or so. Again I had to
, they couldn't figure out what I was doing. Make then really become sky busters
. Watched them really burn their ammo up. I could go on for hours about this. Lots of fun.Back on Primer pocket condtioners. What I am sending you would give a good idea of how to constructed one for rifle brass. I don't think it would take to much to build one or it for rifle cases.
I load for 28ga, 12ga, 20ga. in 2 3/4" length. with Ponsness/Warren presses. Looking at getting a Ponsness/Warren Press that from my understanding you can change out from 410 2 1/2 to 10ga in any lengths. I going to back in their country in a month or two to see what they really have.
Here info on primer pocket reconditioner. (found it)
Mike Matteson
Well-Known Member
That what I had copied down. Interesting. I will revise it. Thanks, and I am glad somebody has tried it. The bolt if a grade 9 work?
RockyMtnMT
Official LRH Sponsor
I think primers are very difficult to read and the pressure indicator that I pay the least attention to. For the hand loader that doesn't have pressure testing equipment (most all of us) the pressure story is told by all of the indicators together. Not just one. Some rifles leave an ejector mark on all loads. This is why I start low in my load development. I want to see and feel the rifle at very mild loads and work up from there. Watching the velocity, bolt lift, case head, primer, and primer pocket. I think the best indicator is how the rifle feels as the pressure increases. When the bolt lift and ejection starts to feel different, the pressure is getting close to top end. Very well built custom rifles will hide the pressure felt on bolt lift. That rifle that shows ejector marks at mild loads will get to a point where the look of those marks becomes more pronounced. In other words when it starts to change its the point where you need to pay attention. As you work up watching your velocity increase nice and consistently with each increase in powder charge and you start seeing larger increases in speed with same increase in charge or more important a spike or larger jump in velocity, this is an indicator that you are starting to push pressure. But not if your velocity is low and all the other indicators show low pressure. If velocity is high and all the other indicators are saying top end that spike in velocity is likely a very good indicator that you are likely pushing the envelope.
So, my point is there are many things together that tell the pressure story. I pay most attention to how the rifle feels and the least to the primer. I pay attention to how all of these things change as I work up from mild. Starting too high deprives the shooter from feeling and seeing the changes.
So, my point is there are many things together that tell the pressure story. I pay most attention to how the rifle feels and the least to the primer. I pay attention to how all of these things change as I work up from mild. Starting too high deprives the shooter from feeling and seeing the changes.
DoneNOut
Well-Known Member
That should do it.
