Pressure signs way below max load

[John 264]

Mine is like 3.7 coal with a 215 Berger and that was with a factory chamber. Could be but that bullets jumping a mile

If it is set that long do they fit in the mag box

 

[varminthunter98]

Sounds to me like a .298 tight bore palma barrel.

 

[Clark]

I have done thousands of overload work ups to see what happens.
What should happen is an expansion of the extractor groove that compromises the primer pocket:
The belted magnum case head is slightly stronger than the Mauser Large Boxer primer case head and slightly weaker than the 223 case head.

6mmBR and rimmed cases should be so strong the primer pierces before the pocket will go loose...............but not with Norma brass.

Norma brass is soft as baby poop after spinach night.

 

[Will Gray]

I don't have a COAL gauge so I use the stone age method. I clean the chamber and barrel, clean and full length resize a piece of brass, check the length, then I push the brass in with my finger and "gently" push it out with a brass rod. No resistance felt (could stand the rifle up, would fall out). Then I press in a bullet leaving it intentionally long and push that in the chamber with my finger and feel for resistance when I push it out with the brass rod. I repeat shorten and try shorten and try until I no longer feel resistance (the bullet is off the lands). That is the length I set for loading and go shoot a few. I make sure that I have sufficient seating depth to be sure there is a good grip on the bullet in the neck of the case. All this adds to the fun of reloading and shooting: great hobby.

 

[Stgraves260]

Ladies and Gents,
I have a Win M70 in 300 win mag that has a 29in Krieger barrel with a brake and glass bedding done by a reputable gunsmith.
I understand how min and max loads from reloading books work, however beyond that could you think at any other reason why I see pressure signs below max load. I use Norma brass new and fire formed and I constantly see pressure signs 1.5 to 2.5 grain below max load with with different powders and bullets. H1000 imr 7828ssc, retumbo

I'm not a gun smith but I know it has to do with the throat tolerances. Like how far the bullet set into the lands also. There needs to be more jump from the bullet to the lands. I don't understand all of it but when I had my Krieger Barrel put on my 260 Rem the gunsmith told me he set the through long so I could load hotter. The max charge on my 260 the reloading books say 40 grains. I'm loading mine to 42.5 grains. I've loaded mine to 44 grains with no pressure signs but the accuracy is not there, so I load with 42.5 grains. I have learned over the years that there is gunsmith out there that do it straight by the book. Then there is gun smiths that have fielded experience. I choose my gunsmith with the field experience. Did a little long rang shooting talk with him. I could tell instantly he is a shooter and not just a gunsmith. A gunsmith is like a college graduate. I know what I'm doing I went to college. But when you ask, they have no field experience. A great gunsmith has tons of field experience.

 

[Roughwater]

I just read the 1st page and saw no need to go further. You may not be able to use the max load but your velocities I can see are beyond max for a 200+ gn bullets from a 300 WM unless you have a very long barrel? If you see holes in your primer/primers you surely have pitted your bolt face. Thats showing EXTREAME pressure! If your velocities are max or beyond I wouldn't worry that you cannot reach the max powder load. I would consider it a good thing.

 

[Whitey1]

I have been waiting for someone else to have an issue like this. I have gotten to the point of considering a new barrel. Op, how difficult is the resizing of your fired brass? Reason I ask is I have a tight chambered and tight bored 7mm mag in a savage Lrh. It took me an embarrassingly long time to realize this. I was down to over 10 grains below (I believe it was 56.5) minimum charge weight with retumbo and 162s. Random primers blowing and found it doing over 3400 fps once I decided to purchase a chronograph. When I full length resized my brass the compression of the walls was almost non-existent but the neck of my brass seemed to flow forward towards the rifling and it would develop a curl in the mouth of the brass after a single firing. Do you noticed anything different in your resizing compared to other calibers or rifles? Like a difficult neck compression and expansion? Or even it hanging up on the way down over the neck expander?(Guess that only works if you re-oad for more than this one..) I am wondering if the reamer used to cut that chamber was exceptionally on the tight side too.

 

[fmuguira]

Based on your velocities I d say you re maxed out, even with a 29" barrel.

Back it down a bit and find your accuracy while watching velocity so you don't go too low. I wouldn't get hung up on the fact it's taking 'less powder' ; there's pressure for that velocity so just move down and enjoy!

 

[T3ninja]

Node, not nose

I agree with both. Better have have a nose too than max speed lol.

 

[Shadowwalker]

If u had pressure at 76 why would u even try 78?

Very good....

 

[436]

Ladies and Gents,
I have a Win M70 in 300 win mag that has a 29in Krieger barrel with a brake and glass bedding done by a reputable gunsmith.
I understand how min and max loads from reloading books work, however beyond that could you think at any other reason why I see pressure signs below max load. I use Norma brass new and fire formed and I constantly see pressure signs 1.5 to 2.5 grain below max load with with different powders and bullets. H1000 imr 7828ssc, retumbo

You might want to read up on the phenomenon of detonation when using slow-burning powder, and magnum cases with minimum charges, that would include high ordnance explosives going off at low ordnance, and low ordnance going off at high ordnance. and yes, double-check your scales, then check them again. only my 0.02 Cheers.

 

[tony d willIiams]

Weight a couple of 100g bullets to verify your scale. What high pressure signs are you seeing, ejector hole marking the case or sticking cases and flat primers (change primer brand)? Are the primer pockets enlarged? Try some other brass. Shoot a box of commercial ammo (heavy bullets) and see how they do.

Most laboratory or instrument stores have weights which are calibrated for checking scales. I check and calibrate my digital scale before and recheck at end of reloading.

 

[skipglo]

Ladies and Gents,
I have a Win M70 in 300 win mag that has a 29in Krieger barrel with a brake and glass bedding done by a reputable gunsmith.
I understand how min and max loads from reloading books work, however beyond that could you think at any other reason why I see pressure signs below max load. I use Norma brass new and fire formed and I constantly see pressure signs 1.5 to 2.5 grain below max load with with different powders and bullets. H1000 imr 7828ssc, retumbo

Seating depth is a key element...the shorter your COAL is from what the book states per load the more you are increasing your pressure

 

[338 dude]

Ladies and Gents,
I have a Win M70 in 300 win mag that has a 29in Krieger barrel with a brake and glass bedding done by a reputable gunsmith.
I understand how min and max loads from reloading books work, however beyond that could you think at any other reason why I see pressure signs below max load. I use Norma brass new and fire formed and I constantly see pressure signs 1.5 to 2.5 grain below max load with with different powders and bullets. H1000 imr 7828ssc, retumbo

From what I've read so far I believe your problem lies with seating depth you need to know the exact distance to your lands for your rifle going by the book will more than likely be way short therefore you're having a smaller combustion chamber by seating the bullet deeper in the case that will also raise pressure the same as jamming a bullet into the lands