What does "safe" mean?

[Creedmoor shooter]

I don't know Alex, but what I can say is reading his posts that he always has a reasonable explanation for his stands that to me make logical sense.

I'm not taking sides with anyone. I'm sure both have faults but this ridiculous name calling and butt hurtness (if that's a word) is getting old.

 

[can1010]

different opinions are what make this site great. but lately the name calling and smart *** comments are out of hand.

 

[ak7an]

I do enjoy a respectful debate..

 

[dmoon]

I for one would like to get back to the "Friendly and Informative" site that this used to be. We are all passionate about shooting sports and all that it encompasses, but getting venomous and adversarial, is not in the best Interest of the site and its benefits. I for one will try to be more respectful and reap the benefits.

I have been a member of many sites that this adversarial atmosphere
was the norm and they did not help the new guys that needed help. These sites were full of guys with great credentials and believed that they were the experts and that everyone with a different opinion was un informed or just plain stupid So I decided to move on and allow more of these type of people to occupy that space.

I like this site and hope that it does not become one of those "Other" sites. As long as I have been on this site I have never felt the need to Ignore anyone. Just because they have disagreed with me. I have gotten upset when personal shots were taken at me and tried not to respond in the same way (But I have Invited several to come to my house and say that to my face) But after a cool down period and reflection I decided to move on.

I can only hope this site remains that type of site with the emphasis
on sharing each persons opinion and expertise.

Do I hear an Amen ?

J E CUSTOM

Thanks for the well put thoughts JE, Amen

 

[Mikecr]

How does velocity not tell you when you have exceeded a safe threshold of pressure when it is pressure that propels the bullet down the barrel..

It's because your reference in this case is expected velocity from a manual, which is not calibrated to your components, including bore dimensions, bullets, seating, and powder lot differences.

So if you think 3kfps is max based on a manual, this may be wrong, and then a change leading to 3.2kfps, may still mean little about max or safe pressure.
Differences could be the result of different powder burning differently in a different bore with different bullets (lots to lots).

MV is input, and all input could be useful. Just be careful that all your inputs are not tainted by (w/resp to) single assumptions.

 

[5RWill]

While i've never blown a primer i often wonder where i stand pressure wise and how safe it is. Take the 6.5x47 people (including myself) constantly push well past what manuals state for the little cartridge to get the extra velocity out of it. The brass last forever and it seems fine. Based on what my friends say with quickload the pressure is well up there. Ejector marks, flattened primers, and tight bolt lift are what i look for. I had been scratching my head for a while shooting suppressed in cold temperature and getting random pressure spikes on what was manual safe. Turned out i had water/liquid in the chamber some how, be it condensation or lube, idk, but it it was the direct result of my pressure spike in my short 6.5x47.

I think reading primers also holds merit but truthfully without a high res image and magnifying it i'm always skeptical of my ability to do so.

 

[Mikecr]

Underbores like a 6.5x47L have the advantage in that you can jack up the pressures to the point of overriding many variables. That's why underbores like 6ppc or 30br are inherently accurate.
Knock em down to normal pressures and that advantage disappears.

But so far the 6.5x47L 130s represents the largest viable underbore. Any larger chamber area and you cannot easily tread so high in pressure.
Next up is the 260AI. But this would take a build plan that includes greater than normal barrel steel around the chamber. And it would be very competitive with 140s and the fastest filling powder.

There are many things that influence pressure problems and unsafe pressures. SAAMI cannot account for local conditions, and I'm pretty sure SAAMI provides what a manufacturer requests at times.
When Winchester wants SAAMI max at 65Kpsi for WSM/WSSM cartridges, they send SAAMI barrels they intend to use & sell. They have SAAMI confirm it's safe. Otherwise, SAAMI may have used smaller tenon barrels and came to lower MAX values.
So when you consider SAAMI MAX for cartridges small to large, there is not a solid trend there, other than overall -larger cartridges are rated at lower max pressures(all else equal). But again, that's not YOUR setup.

 

[Gregg C]

Underbores like a 6.5x47L have the advantage in that you can jack up the pressures to the point of overriding many variables. That's why underbores like 6ppc or 30br are inherently accurate.
Knock em down to normal pressures and that advantage disappears.

But so far the 6.5x47L 130s represents the largest viable underbore. Any larger chamber area and you cannot easily tread so high in pressure.
Next up is the 260AI. But this would take a build plan that includes greater than normal barrel steel around the chamber. And it would be very competitive with 140s and the fastest filling powder.

There are many things that influence pressure problems and unsafe pressures. SAAMI cannot account for local conditions, and I'm pretty sure SAAMI provides what a manufacturer requests at times.
When Winchester wants SAAMI max at 65Kpsi for WSM/WSSM cartridges, they send SAAMI barrels they intend to use & sell. They have SAAMI confirm it's safe. Otherwise, SAAMI may have used smaller tenon barrels and came to lower MAX values.
So when you consider SAAMI MAX for cartridges small to large, there is not a solid trend there, other than overall -larger cartridges are rated at lower max pressures(all else equal). But again, that's not YOUR setup.

That is very interesting. I load US869 in my 338-378 why. Listed loads for that cartridge are always (pressure) in Copper Units of Pressure, not PSI. Don't know why, do know there is no co relation. Any way, US869 is seemingly low in pressure for velocity. For instance, max load shown for 300gr SMK shows pressure at 48,700cup, producing 2782fps in their test rifle. Retumbo is shown with 53,000cup, producing 2818fps. Always wondered why the manufacturer doesn't bring the pressures on different powders to equal or near equal values. Anybody got any ideas on that ? Might help me sleep better at night.....
Gregg

 

[RockyMtnMT]

So I always load with a chronograph and use it as part of the equation. I study load data from several manuals for like weight bullets. Vel is a very good indicator of pressure. If the vel is way high you know you are over pressure even if other signs are not showing. Full custom rifles are guilty of this because they are very well put together and do not show the classic bolt lift and flat primer etc signs.

Some rifles will pressure out before max vel is achieved. Big chamber or tight bore, is what it is. Some rifles are fast and some are slow. The chrono is a major tool in my load development, but not the only tool.

Steve

 

[Alex Wheeler]

Underbores like a 6.5x47L have the advantage in that you can jack up the pressures to the point of overriding many variables. That's why underbores like 6ppc or 30br are inherently accurate.
Knock em down to normal pressures and that advantage disappears.

But so far the 6.5x47L 130s represents the largest viable underbore. Any larger chamber area and you cannot easily tread so high in pressure.
Next up is the 260AI. But this would take a build plan that includes greater than normal barrel steel around the chamber. And it would be very competitive with 140s and the fastest filling powder.

There are many things that influence pressure problems and unsafe pressures. SAAMI cannot account for local conditions, and I'm pretty sure SAAMI provides what a manufacturer requests at times.
When Winchester wants SAAMI max at 65Kpsi for WSM/WSSM cartridges, they send SAAMI barrels they intend to use & sell. They have SAAMI confirm it's safe. Otherwise, SAAMI may have used smaller tenon barrels and came to lower MAX values.
So when you consider SAAMI MAX for cartridges small to large, there is not a solid trend there, other than overall -larger cartridges are rated at lower max pressures(all else equal). But again, that's not YOUR setup.

What?

 

[MudRunner2005]

So I always load with a chronograph and use it as part of the equation. I study load data from several manuals for like weight bullets. Vel is a very good indicator of pressure. If the vel is way high you know you are over pressure even if other signs are not showing. Full custom rifles are guilty of this because they are very well put together and do not show the classic bolt lift and flat primer etc signs.

Some rifles will pressure out before max vel is achieved. Big chamber or tight bore, is what it is. Some rifles are fast and some are slow. The chrono is a major tool in my load development, but not the only tool.

Steve

My custom A-Bolt II 7mmRM has a match-chamber with a tight SAAMI neck, so I don't have to neck-turn my cases, and my brass lasts nearly forever from barely any expansion and contraction, and only being neck-sized. I have noticed that the tri-lug design of the A-Bolt II masks bolt-lift pressure signs very well. For example, I can measure swelling of the belt with my calipers and notice when pressures are getting excessive. Thanks to the tight chamber specs, I've found my rifle's safe max is only 1.2 grains over Berger's book max with a 168 VLD, and the cases look great. However, velocities are blistering at over 3,100 FPS MV (measured on my MSv2) from a 26" barrel. Externally there's no excess pressure signs, but the primers have a much greater pancake lip. So, then I carefully decap the brass and measure the outer [flattened] edge of the primers with my calipers. I also measure belt swell. Average swell is .0006" to .0008", so if I hit .001", I know I need to back it down to a safe charge, which turned out to be right at 66 grains.

Now, disclaimer, while these measuring procedures were general practice for professionals back in the day before all the fancy tools and electronics, I am not saying they are very precise or consistent ways to measure pressure, unless you keep logs of this information, and you measure all of your brand new brass cases (especially between different lots), and log that info for future reference, before firing them. Also, your standard .001" calipers will not work, you will need calipers that measure to the .0001".

And for anyone who wants to get ****y and claim this is unsafe practice...Get mad at Hodgdon, not me. http://www.hodgdonreloading.com/rel...-trick-monitoring-pressure-your-rifle-reloads I read about this procedure years ago, and have been using it for years, and I just happened to find that Hodgdon has also listed it on their website, so it's obviously not too unsafe of a practice, or else they wouldn't be posting it for people to use.

 

[Rich Coyle]

That is very interesting. I load US869 in my 338-378 why. Listed loads for that cartridge are always (pressure) in Copper Units of Pressure, not PSI. Don't know why, do know there is no co relation. Any way, US869 is seemingly low in pressure for velocity. For instance, max load shown for 300gr SMK shows pressure at 48,700cup, producing 2782fps in their test rifle. Retumbo is shown with 53,000cup, producing 2818fps. Always wondered why the manufacturer doesn't bring the pressures on different powders to equal or near equal values. Anybody got any ideas on that ? Might help me sleep better at night.....
Gregg

I asked a powder company rep once. He said the reason for the difference is the more consistent powder can be run to higher pressures because they don't "spike" occasionally. They try to keep the "spike" to a save level.

 

[cajun]

So I always load with a chronograph and use it as part of the equation. I study load data from several manuals for like weight bullets. Vel is a very good indicator of pressure. If the vel is way high you know you are over pressure even if other signs are not showing. Full custom rifles are guilty of this because they are very well put together and do not show the classic bolt lift and flat primer etc signs.

Some rifles will pressure out before max vel is achieved. Big chamber or tight bore, is what it is. Some rifles are fast and some are slow. The chrono is a major tool in my load development, but not the only tool.

Steve

This. If you use a chrono and stay within published velocities you will be safe, your barrel and brass will last longer and you won't be out there on a really hot day and have to hammer your bolt open.

When I first got into reloading in the 80's a friend of mines dad was a big time reloader and shooter. This was back when the loading manuals were not quite as lawyered up as they are today. He routinely pushed the envelope and hot rodded his guns. I can't tell you how many times he had a load that was just fine one day and the next time you couldn't open the bolt.

I see a lot of guys running 6.5 creedmor 140's 2800ish up to 2900 with h4350 even though the highest listed velocity in any manual is in the 2700's. They are for sure running above 62k which is saami but probably less than the 70K range where you start seeing issues with primers. Lapua brass and small rifle primers can take a good beating. As for me if I want 6.5 284 velocities I will build one. The extra few fps is just not worth it.