Is This Excessive Pressure??

[Ingwe]

Most Alliant powders are temp sensitive. RL26 seems to be better and RL16 is supposed to be as well. I have no experience with RL16. As I stated before you are getting speeds that are easily obtainable with H1000 which is arguably the best powder for many of the magnums including the 7mm rem mag. To answer your question, yes all powders are temp sensitive. When we say they are not we are really saying not near as much. most of the hogdgon extreme powders are .5fps per degree or less. Some of the Alliant powders are well over 1fps per degree. I have never noticed my poi changing with H1000 or H4831 outside of what my ballistic calculator predicts due to weather/atmospheric conditions.

Thanks for the explanation and I get it. I am working with RL33 because I have 10lbs of it

 

[Rhovee]

The whole velocity=pressure isn't at all true. Take a look at any reloading manual. Faster powders pressure out at lower velocity. Notice the slower powders achieve more velocity. Add in the fact that some barrels are faster.

 

[Pdvdh]

It's largely true, with some stipulations and conditions. And you identified big one, powder burn rate.

 

[Tex LR]

In over three decades, I have experienced two memorable situations of "Excessive Pressure" when reloading for maximum velocity. The first with a .264 Win mag, the second with a 25-06 AI. Looking back, in both cases I should have backed off at the first signs of over pressure. I was fortunate that the subsequent case failures were contained in the rifles but the close calls were a wake up call for me. Chasing another 100 FPS can be dangerous. When you see signs of pressure, its time to back it down.

 

[Pdvdh]

Yup

 

[FURMAN]

It's largely true, with some stipulations and conditions. And you identified big one, powder burn rate.

I am confident you as well as Jasonco understand this concept but we need to keep in mind that a lot of new people are getting into our sport and may be coming to this forum to find, what they would expect to be, accurate information and this statement is missing a huge piece of the physics puzzle. Powder charge and room to use said charge(barrel length) are just as important if not more so than pressure. A 30 br with 30ish grains of powder pushing a 215 bullet at 60k psi will not yield the same velocity as a 30 Nosler with 80ish grains of powder at 60k psi. Again I am confident, certain really, you two understand this but new readers may not.

 

[FURMAN]

Ingwe, please report back with your findings of temp stability when you find your load and have more data.

 

[338 dude]

I would appreciate hearing your comments on these pic's.

Fired from a 7mm Rem Mag loaded with 78.0gr of RL33 pushing a 175gr Nosler Accubond LR at 2,922fps.

I am seeing some cratering on the primer but it doesn't look flattened-out and hasn't spread out. I don't see any marks on the case either.

What do you guys think...does it look safe or excessive?

The second pic (lighter-shiny brass) is loaded with 79.0gr of RL33. The cratering is a bit more pronounced but not by much.

The extra grain of powder is only giving me an extra 13fps so I would go with the 78.0gr if you guys think it's OK.

Whatdaya Think?

On the second cartridge the edges of the primer appear sharp no longer rounded that is a sign of excessive pressure the first cartridge is OK

 

[raider1v1]

well its probably fine at 78.0 if it was a temp stable powder and all of the cases looked like that. the safe bet would be going w/ 77.5. the question id ask is "if something exploded how dumb would i feel for that extra few FPS?". my usual answer is "very dumb.".

thats my own internal safety check.

 

[BLK]

I would appreciate hearing your comments on these pic's.

Fired from a 7mm Rem Mag loaded with 78.0gr of RL33 pushing a 175gr Nosler Accubond LR at 2,922fps.

I am seeing some cratering on the primer but it doesn't look flattened-out and hasn't spread out. I don't see any marks on the case either.

What do you guys think...does it look safe or excessive?

The second pic (lighter-shiny brass) is loaded with 79.0gr of RL33. The cratering is a bit more pronounced but not by much.

The extra grain of powder is only giving me an extra 13fps so I would go with the 78.0gr if you guys think it's OK.

Whatdaya Think?

 

[BLK]

Sure looks like the first signs of over pressure to me. Could be several reasons though. Not only the amount of powder. 1. Too much powder.
2. Wrong primer/powder combination. 3. Slop in bolt face to casing base. 4. Overall bullet depth.
Any of the above can show similar signs. Back off the power a grain or grain and one half and see what it does for you. No sense beating your rifle to death.

 

[jmfishin]

I would appreciate hearing your comments on these pic's.

Fired from a 7mm Rem Mag loaded with 78.0gr of RL33 pushing a 175gr Nosler Accubond LR at 2,922fps.

I am seeing some cratering on the primer but it doesn't look flattened-out and hasn't spread out. I don't see any marks on the case either.

What do you guys think...does it look safe or excessive?

The second pic (lighter-shiny brass) is loaded with 79.0gr of RL33. The cratering is a bit more pronounced but not by much.

The extra grain of powder is only giving me an extra 13fps so I would go with the 78.0gr if you guys think it's OK.

Whatdaya Think?

Check head space I had a similar problem, drove me nuts had the bolt bushed for the firing pin and still had problem turned out be head space

 

[Cowboyshooter]

I would appreciate hearing your comments on these pic's.

Fired from a 7mm Rem Mag loaded with 78.0gr of RL33 pushing a 175gr Nosler Accubond LR at 2,922fps.

I am seeing some cratering on the primer but it doesn't look flattened-out and hasn't spread out. I don't see any marks on the case either.

What do you guys think...does it look safe or excessive?

The second pic (lighter-shiny brass) is loaded with 79.0gr of RL33. The cratering is a bit more pronounced but not by much.

The extra grain of powder is only giving me an extra 13fps so I would go with the 78.0gr if you guys think it's OK.

Whatdaya Think?

What is the brand of primer?
The photos are hard to use, as the difference in lighting is misleading. While measuring the photos does not show any real difference in dimensions, it is hard to accurately see the shoulders of the primers. Without the brand, it is harder to evaluate the results.
Would I say these photos indicate a high pressure/over pressure condition, not really. More than anything this looks like an over sized firing pin hole in the bolt or and this is something that is often over looked, a weakening firing pin spring. If the firing pin spring is light, it can allow the firing pin to move back during the pressure period, causing the situation you see, allowing a ring to form. Then the pin can move back forward towards the end of the pressure period, making the center of the primer look "normal", but with a pressure ring around the edge.
The firing pin will bounce on the primer and can cause some accuracy issues.
So overall, there is some missing information needed to completely evaluate these two lone photos.
Hope this helps or at least gives some food for thought and further examination.

 

[JanP]

Sure imho!