300 win mag and 215 Berger questions

[Yotehtr1]

While I cannot prove this, logic suggests it's probably true. I have long believed that neck tension, powder charge shape differences ( flat or toward front or back of case) and jump can both create pressure and velocity variations. I have seen similar results to yours. I think bullets from round to round move into the lands at different times.

There have been numerous cases of modern smokeless 45 cal muzzle loader barrels blowing up. Many of us feel the bullets vibrate off the powder column during handling. This creates a pipe bomb. I believe the same thing to be true with some loads in centerfire rifles and can get far worse with jump.

I believe that bullets, particularly heavy for caliber bullets, can jump out of the neck on ignition, then jam into the lands and stall. This gives the powder more time and space to burn and build pressure The pressure builds way past normal levels as it tries to re launch the bullet that is now .020" or more into the lands. For that round you are basically shooting a round that is the same as a jammed load.

this condition varies from round to round and in my opinion can get far worse as jump increases. In a perfect world we imagine a bullet launching like a missile. In this case the bullets stutters.

Ive chased similar moving pressure signs at lower than max loads too in a 50bmg. I trimmed several cases, turned the necks, used a bushing and crimped all the loads. Never saw another spike.

I don't know about your procedures but I am very fussy about inside neck wall prep. Every case is cleaned, sonic washed, I run a rotary brush with acetone inside my necks. My goal is to create exactly the same resistance and tension from round to round.

I honestly just brush them out with a case neck brush. Hadn't had issues before but that doesn't necessarily mean anything either

 

[cb4128]

Something that hasn't been brought up yet - check your brass OAL. Make sure it's in spec. If it's a little long (since it's once fired and you didn't mention trimming it) it could cause a spike in pressure.

Also, that 72.0-73.0gr increment looks to be a nice node for you, with the decrease in velocity.

How is that load shooting? Have you done any accuracy testing?

 

[Heym500]

Try fed. 210 primers.

 

[Yotehtr1]

Something that hasn't been brought up yet - check your brass OAL. Make sure it's in spec. If it's a little long (since it's once fired and you didn't mention trimming it) it could cause a spike in pressure.

Also, that 72.0-73.0gr increment looks to be a nice node for you, with the decrease in velocity.

How is that load shooting? Have you done any accuracy testing?

I'm sorry I didn't mention but all brass was trimmed to 2.610 I believe I don't have my notes in front of me right now. Shoulders were bumped 0.0015 in Forster full length die, primer pockets were all uniformed, flash holes chamfered and debuted, necks inside vld chamfered and outside chamfered. That's all the prep work I did other than cleaning. And yes right in that 72-73 area looks promising. I haven't done any accuracy testing there yet though. I remade the loads I fired plus a few more last night and fully cleaned the action, chamber, and bore because it was suggested to me that possibly moisture or gun oil in the action may have had something to do with causing a spike. I made sure it's all very clean and dry. I also loaded a few Extra charges down low to re foul the barrel before I get back to the 72-73 grain range. Hoping to make it back out this week again

 

[Robert M Boren Sr]

Why even mess with H1000, I have some and tried it, it was way too inconsistent, I switched to Ramshot Magnum and never looked back, it works great in all my Magnum calibers, 338 RUM, 300 WIN, 7MMS Rem Mag. If a powder gives you that much variances between lots, don't use it, just my opinion.

 

[thwatson2]

I've had problems with varget that compare to yours. First thing I'd do is try a different powder and keep everything the same then see if you get same results. If you have same velocity issue check for crimp issues, I've overcrimped before and had increase velocity and higher poi If your other powder responses more like expected, then that powder is just hotter. Regardless of result, it's why we chrono our loads and don't use others results. One gun and one powder doesn't always give the same results. Good luck with your load development. As an aside, I was in Montana last summer for the Quigley, I had to come down several points to hit steel. I came back to coastal SC and had to raise sights back several points for each target Nothing but the environment changed. Shooting can be very mystifyin, but makes it fun and interestin.

 

[stljc2]

I was just down at the range this morning to start load development with 215 Berger's in my 300 win mag. What I discovered is much higher velocities than Berger predicted at lower charges. And I saw pressure signs at a fairly mild load in one instance and stopped there. Here's the specifics. According to my comparator my cbto measurement at the lands is 2.871. Berger recommended starting 0.015 off. This made my cbto 2.856 with my comparator set giving me 3.649 total cartridge length base to tip. I'm using once fired federal brass, federal 215M primers, and h1000. The suggested starting load was 70.5 grains at 2632 fps and a max of 74.0 grains at 2772 fps. They used a 26" barrel and so am I. I loaded 11 rounds every half grain from 71.5 to 76.5 to look for pressure signs in my rifle. At 71.5 I matched their max velocity at exactly 2772. 72 grains gave me 2812, 72.5 gave me 2855, 73 gave me (oddly) 2842, 73.5 gave me 2879, and 74 gave me 2917 but with faint ejector marks. All primers were somewhat flat but didn't appear at all alarming and I never got a sticky bolt lift. I then decided to run up with another set every 0.2 grains. First was 72.6 with two shots 2818 and 2836. Second was 72.8 grains with 2842 and 2830. The 72.8 grain load produced very faint ejector marks on one case but not the other. In the first series I didn't see pressure until right about max charge which was understandable and the second set showed up 1.2 grains sooner which was odd. Velocities of the 72.8 charge were in the ball park with the initial 72.5 and 73.0 grain range. What I'm confused on is the much higher than listed velocities. What should I be checking? Generally I've had a hard time matching book velocities let alone exceeding it by a significant amount. I was under the impression seating out longer and increasing case volume would lower pressure but that doesn't seem to fit with what I'm seeing. Sorry for the long read but wanted to be as specific as I could. Temperature today was 32 degrees

I think I'd re-check my Base to lands overall measurement. Sometimes mine gets goofy and gives false readings. I keep going 5 x's and see which are consistent and stick with that. I could be wrong but it has worked for me.

 

[Stgraves260]

I was just down at the range this morning to start load development with 215 Berger's in my 300 win mag. What I discovered is much higher velocities than Berger predicted at lower charges. And I saw pressure signs at a fairly mild load in one instance and stopped there. Here's the specifics. According to my comparator my cbto measurement at the lands is 2.871. Berger recommended starting 0.015 off. This made my cbto 2.856 with my comparator set giving me 3.649 total cartridge length base to tip. I'm using once fired federal brass, federal 215M primers, and h1000. The suggested starting load was 70.5 grains at 2632 fps and a max of 74.0 grains at 2772 fps. They used a 26" barrel and so am I. I loaded 11 rounds every half grain from 71.5 to 76.5 to look for pressure signs in my rifle. At 71.5 I matched their max velocity at exactly 2772. 72 grains gave me 2812, 72.5 gave me 2855, 73 gave me (oddly) 2842, 73.5 gave me 2879, and 74 gave me 2917 but with faint ejector marks. All primers were somewhat flat but didn't appear at all alarming and I never got a sticky bolt lift. I then decided to run up with another set every 0.2 grains. First was 72.6 with two shots 2818 and 2836. Second was 72.8 grains with 2842 and 2830. The 72.8 grain load produced very faint ejector marks on one case but not the other. In the first series I didn't see pressure until right about max charge which was understandable and the second set showed up 1.2 grains sooner which was odd. Velocities of the 72.8 charge were in the ball park with the initial 72.5 and 73.0 grain range. What I'm confused on is the much higher than listed velocities. What should I be checking? Generally I've had a hard time matching book velocities let alone exceeding it by a significant amount. I was under the impression seating out longer and increasing case volume would lower pressure but that doesn't seem to fit with what I'm seeing. Sorry for the long read but wanted to be as specific as I could. Temperature today was 32 degrees

The closer you are to the lands the higher your pressure will be. Give your bullet more jump. Thank of it this way. If it was possible take a nail and a 2x4 piece of wood. Touch the nail to the wood and push it through the 2x4. That would be pretty tough. Now take that same nail and start back far enough to let you gain some speed. It would be much more easy to drive the nail in the 2x4.

 

[stonehands1]

The closer you are to the lands the higher your pressure will be. Give your bullet more jump. Thank of it this way. If it was possible take a nail and a 2x4 piece of wood. Touch the nail to the wood and push it through the 2x4. That would be pretty tough. Now take that same nail and start back far enough to let you gain some speed. It would be much more easy to drive the nail in the 2x4.

While this is true in some cartridges it does not apply to every cartridge. Case in point when developing loads for a weatherby cartridges, seating bullets out .200 from sammi has actually lowered measured velocity. I believe this is due to increasing case volume. Have also seen this when seating out as little as .020-.030 as well.
That being said I have also seen pressure increase when seating bullets at the lands.
I agree with your analogy in theory but have seen the opposite in testing. A lot of Leade angle will cause pressure signs below calculated velocity in new barrels. Once the rifling is eroded enough so as to create a lower leade angle pressure signs go away and velocity will increase.

 

[Stiletto150]

My understanding is with the extra case space. Since your case is over saami creates more velocity. Probably from dwell time before it hits the lands.
Cheap insurance and to rule out. RCBS has check weights. Part #98993 or 98992
Not sure if your balance was ever corrected with the shot in the bottom of the hanger.
***I had one balance scale of by a grain and one time I whacked the scale and didn't know it until I did a recheck. it put me 2 grains under. lucky I didn't go 2 grains over.

 

[wonderman4]

I was under the impression seating out longer and increasing case volume would lower pressure but that doesn't seem to fit with what I'm seeing.

As Stgraves260 stated above, The closer to the lands you get, the higher the pressure will be. Then you add in tolerances, and you are inviting disaster when not taken into account for.

The reason Roy was able to get such velocities out of his creations without blowing primers, cases, rifles, etc was the freebore (think large jumps to the lands). Within limits, pressures can jump 10K-15K with small jumps to touching the lands.

 

[Yotehtr1]

As Stgraves260 stated above, The closer to the lands you get, the higher the pressure will be. Then you add in tolerances, and you are inviting disaster when not taken into account for.

The reason Roy was able to get such velocities out of his creations without blowing primers, cases, rifles, etc was the freebore (think large jumps to the lands). Within limits, pressures can jump 10K-15K with small jumps to touching the lands.

Might be worth backing off another 0.010 and see if that helps

 

[Southernfriedwerewolf]

I've had excellent success with Ramshot Magnum and Berger's, 28" Kreiger barrel

 

[freddiej]

Do you have Hornady's #9 reloading book, please read page 24, 25 and 26. you will correct some of your thinking about bullet seating VS pressure and velocity.
you sound like you have either a tight chamber or thick brass. it could be that you have a slightly hotter lot of H-1000.