Son, Since my grandson is now an experienced hand loader, and since I have a box of reloads dated 1958, be assured that I use that term with respect and some level of experience.
First point: Hogdon manual and most other published max loads have decreased over the long term from legal concerns. A 4895 1970 max load is not the same as a 2008 max load.
#2 The specific data source for OCW load is Practical Riflery Forums... techniques and equipment of the practical rifleman... :: Index
#3 I have published a primer intensity article based upon actual pressure measurements done by another; have you studied it?
#4, With respect, do you start with computer load program or programs to see if your proposed load has an associated pressure number or warning?
As a general purpose or mission statement,I view these posts as intended to move the knowledge and safety of our sport along. I have nothing left to prove or sell yet the oldest of us think we will still be learning when the lid on the coffin goes shut. Cordially, Overbore
My load work up is simple. I check 2-3 sources. For instance, If loading for my .280, I'd look at say Nosler and Hornady. Both give very similar data for R-19 and their respective 139/140gr bullets. 57 max for Nosler at 3150 from a 26" bbl, and 57.4 for Hornady at a little over 3000 in a 24" bbl. I figure knocking off about 50-75fps from Nolsers velocity for my expectations for R-19 and 140 grain bullets because I'm shooting 24" bbl. I start a few grains under max for the given powder/bullet combo. I start at about 54 grains, and check accuracy and velocity. Supposing it's under the listed velocity given of around 3050 for the top end loads in the books, I work up. If my 54gr load is 2500fps, I may add 2 grains...if its 2850, I'll work up a grain at a time until my velocity is in the 3050-3075 range, and call it good if the accuracy is there. If not, then I try another bullet or powder and start over. Add to that now that I check Quickload, and it predicts I should be in safe pressure ranges with my loads, plus the fact that I see no outward signs of pressure and brass life is good over the last 20 years, I figure I'm good to go, even though I'm using 1 more more grain of powder than the book says is max. Differing lots of powder can account for that difference. If I change anything...brass, primer, etc, I back off about 3 grains an start over. Thats an example of how I'd work up a load.
Son, Since my grandson is now an experienced hand loader, and since I have a box of reloads dated 1958, be assured that I use that term with respect and some level of experience.
First point: Hogdon manual and most other published max loads have decreased over the long term from legal concerns. A 4895 1970 max load is not the same as a 2008 max load.
Pressure testing equipment is better today and more accurate, than in 1958. Reloading manuels in the late 50'searly 60's show many loads that were over SAAMI max.
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range it,check the wind, dial in correction, aim and only one shot
My load work up is simple. I check 2-3 sources. For instance, If loading for my .280, I'd look at say Nosler and Hornady. Both give very similar data for R-19 and their respective 139/140gr bullets. 57 max for Nosler at 3150 from a 26" bbl, and 57.4 for Hornady at a little over 3000 in a 24" bbl. I figure knocking off about 50-75fps from Nolsers velocity for my expectations for R-19 and 140 grain bullets because I'm shooting 24" bbl. I start a few grains under max for the given powder/bullet combo. I start at about 54 grains, and check accuracy and velocity. Supposing it's under the listed velocity given of around 3050 for the top end loads in the books, I work up. If my 54gr load is 2500fps, I may add 2 grains...if its 2850, I'll work up a grain at a time until my velocity is in the 3050-3075 range, and call it good if the accuracy is there. If not, then I try another bullet or powder and start over. Add to that now that I check Quickload, and it predicts I should be in safe pressure ranges with my loads, plus the fact that I see no outward signs of pressure and brass life is good over the last 20 years, I figure I'm good to go, even though I'm using 1 more more grain of powder than the book says is max. Differing lots of powder can account for that difference. If I change anything...brass, primer, etc, I back off about 3 grains an start over. Thats an example of how I'd work up a load.
I will further address my "velocity indicates pressure" by saying that if my starting load above of 54grs showed a velocity of 3000fps, then I would not say "Hey I got a fast gun" and continue to work up to the "book max powder charge" because the book says that's a safe max load. I would have in fact started at my gun's max load, though inadvertently.
Also, I have read some things on primers and their effect on pressure/velocity. The consensus seems to be there is nothing that is scientifically predictable about it. The effect primer change can have is dependant on many other factors such as load density, powder burn rate, case capacity, bullet wt. etc. Now in any particular application you might could find a trend with regard to primer's effect on velocity/pressure, but the rules will be different for a .44mag using Unique with cast bullets, and a .300WinMag with R-22 and 180gr Copper jacketed bullets. A hotter primer giving less velocity with higher pressure, and a "cooler" primer giving more velocity and less pressure, and vice versa to both have all been observed.
overbore,
I would love to read what you said you wrote about primers. Is it online? Or where can I find it?
When you keep adding powder and velocity does not go up at the same rate it has... pressure and not performance is happening. Let's say you get 50 ft/sec's for each half grain, then you add a 1/2 and only get 35 and another 1/2 yields 23 ft/secs... That powders burning rate is peaking and may not be the correct choice for your application.
Hey .280 about primers? Do you recon that the differences seen could be attributed to other factors than the primers themselves? Like for instrance I have seen primers that will break neck tension and actually push the bullet into the lands. I have also seen primers that would not even budge a bullet. I have heard that a projectile actually stops during the process. Do you think that maybe it isnt the strength of the primer but what they do to the projectile?
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I admit that I know just enough to be dangerous.....but dangerous at ever extending distances.
Hey .280 about primers? Do you recon that the differences seen could be attributed to other factors than the primers themselves? Like for instrance I have seen primers that will break neck tension and actually push the bullet into the lands. I have also seen primers that would not even budge a bullet. I have heard that a projectile actually stops during the process. Do you think that maybe it isnt the strength of the primer but what they do to the projectile?
Generally speaking, yes primers can affect pressures with little gain in velocity. But, most problems in reloading can be headed off by working up your loads as recommended. Changing primers under the same powder charge and bullet you've been shooting can cause a problem, depending on the other factors.
In fact primers and their effect are largely un predictable. In some cases a hotter primer can lower velocity, and raise pressure, and a cooler primer vice versa. The key to it all is working up the load with components remaining the same, and watching your velocity, then your brass.
Recently read a post on another site where a guy was loading for the 30-06 with 180s and H4350. Said he hit @ 2730fps some 2.5 grains below "book max". He's started 6.5 grains under max at 2550, and jumped 2 grains of powder and nearly 200fps to the 2730 level with the first and second batch. But since the book said he could add 2.5 more grains, he added 2 more, and got a chrony reading of 2900 fps, and a VERY sticky bolt and extraction with a 180 in a 30-06! I told him that had I been watching the chrony, I'd have stopped at the second loading due to the velocity. And that just goes to show you how worthless a "book max" powder charge is to safety. Had he gone ahead and loaded to "book max" he may have damaged his gun, or worse! The chronograph is your friend IF you use it correctly.
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