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So when you are working up to theoretical safe max in your rifle, how much do you back off when you reach the first signs of pressure. You know the the sticky bolt lift, the ejector mark, or the primer a little to flattened whatever it may be. Do you back off a whole grain, 1/2 a grain, 7/10... just curious what folks do... Mike Legistine actu quod scripsi? Never under estimate the internet community's ability to reply to your post with their personal rant about their tangentially related, single occurrence issue.  What I have learned on AR, since 2001: 1. The proper answer to: Where is the best place in town to get a steak dinner? is…You should go to Mel's Diner and get the fried chicken. 2. Big game animals can tell the difference between .015 of an inch in diameter, 15 grains of bullet weight, and 150 fps. 3. There is a difference in the performance of two identical projectiles launched at the same velocity if they came from different cartridges. 4. While a double rifle is the perfect DGR, every 375HH bolt gun needs to be modified to carry at least 5 down. 5. While a floor plate and detachable box magazine both use a mechanical latch, only the floor plate latch is reliable. Disregard the fact that every modern military rifle uses a detachable box magazine. 6. The Remington 700 is unreliable regardless of the fact it is the basis of the USMC M40 sniper rifle for 40+ years with no changes to the receiver or extractor and is the choice of more military and law enforcement sniper units than any other rifle. 7. PF actions are not suitable for a DGR and it is irrelevant that the M1, M14, M16, & AK47 which were designed for hunting men that can shoot back are all PF actions. 8. 95 deg F in Africa is different than 95 deg F in TX or CA and that is why you must worry about ammunition temperature in Africa (even though most safaris take place in winter) but not in TX or in CA. 9. The size of a ding in a gun's finish doesn't matter, what matters is whether it’s a safe ding or not. 10. 1 in a row is a trend, 2 in a row is statistically significant, and 3 in a row is an irrefutable fact. 11. Never buy a WSM or RCM cartridge for a safari rifle or your go to rifle in the USA because if they lose your ammo you can't find replacement ammo but don't worry 280 Rem, 338-06, 35 Whelen, and all Weatherby cartridges abound in Africa and back country stores. 12. A well hit animal can run 75 yds. in the open and suddenly drop with no initial blood trail, but the one I shot from 200 yds. away that ran 10 yds. and disappeared into a thicket and was not found was lost because the bullet penciled thru. I am 100% certain of this even though I have no physical evidence. 13. A 300 Win Mag is a 500 yard elk cartridge but a 308 Win is not a 300 yard elk cartridge even though the same bullet is travelling at the same velocity at those respective distances. | ||
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Many centerfire loads of smokeless powder generate (very roughly) 3,000 PSI per grain added. Since a lot of pressure signs may not show up until you reach (again roughly) 70,000 PSI it seems reasonable to back off three full grains to roughly 60,000 PSI | |||
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I only push towards book max until I get accurate results. My goal is accuracy first and not ultimate velocity. That said, IF I am below or at max. when brass shows pressure signs, I make sure it is not just softer brass or just one case -- I fire more than one round of a batch -- and want a chronograph speed to check against the book. Personally, though I admit to not pushing any envelopes, I would never be comfortable guessing what actual pressure is, nevermind anybody's rules-of-thumb. _______________________ | |||
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I`d drop a full grain in something like the 223 and a couple grains in a `06. The total would depend on how close to max I was when trouble appeared and whether or not I felt the powder was giving me acceptable results overall. If accuracy wasn`t the best, or velocity lower then I expected, I`d just go to a new powder and start over. ------------------------------------ The trouble with the Internet is that it's replacing masturbation as a leisure activity. ~Patrick Murray "Why shouldn`t truth be stranger then fiction? Fiction after all has to make sense." (Samual Clemens) "Saepe errans, numquam dubitans --Frequently in error, never in doubt". | |||
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BNagel, One of the reasons that I asked the question is that I have had a few rifles that exhibit pressure signs at 5% below "book max". So my working up...is not an issue of trying to necessarily get some over book velocity...it is trying to find optimum safe velocity with reasonable acuracy say 1.5 inches. Mike Legistine actu quod scripsi? Never under estimate the internet community's ability to reply to your post with their personal rant about their tangentially related, single occurrence issue. What I have learned on AR, since 2001: 1. The proper answer to: Where is the best place in town to get a steak dinner? is…You should go to Mel's Diner and get the fried chicken. 2. Big game animals can tell the difference between .015 of an inch in diameter, 15 grains of bullet weight, and 150 fps. 3. There is a difference in the performance of two identical projectiles launched at the same velocity if they came from different cartridges. 4. While a double rifle is the perfect DGR, every 375HH bolt gun needs to be modified to carry at least 5 down. 5. While a floor plate and detachable box magazine both use a mechanical latch, only the floor plate latch is reliable. Disregard the fact that every modern military rifle uses a detachable box magazine. 6. The Remington 700 is unreliable regardless of the fact it is the basis of the USMC M40 sniper rifle for 40+ years with no changes to the receiver or extractor and is the choice of more military and law enforcement sniper units than any other rifle. 7. PF actions are not suitable for a DGR and it is irrelevant that the M1, M14, M16, & AK47 which were designed for hunting men that can shoot back are all PF actions. 8. 95 deg F in Africa is different than 95 deg F in TX or CA and that is why you must worry about ammunition temperature in Africa (even though most safaris take place in winter) but not in TX or in CA. 9. The size of a ding in a gun's finish doesn't matter, what matters is whether it’s a safe ding or not. 10. 1 in a row is a trend, 2 in a row is statistically significant, and 3 in a row is an irrefutable fact. 11. Never buy a WSM or RCM cartridge for a safari rifle or your go to rifle in the USA because if they lose your ammo you can't find replacement ammo but don't worry 280 Rem, 338-06, 35 Whelen, and all Weatherby cartridges abound in Africa and back country stores. 12. A well hit animal can run 75 yds. in the open and suddenly drop with no initial blood trail, but the one I shot from 200 yds. away that ran 10 yds. and disappeared into a thicket and was not found was lost because the bullet penciled thru. I am 100% certain of this even though I have no physical evidence. 13. A 300 Win Mag is a 500 yard elk cartridge but a 308 Win is not a 300 yard elk cartridge even though the same bullet is travelling at the same velocity at those respective distances. | |||
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In bottleneck rimless cases, I like 6% from the threshold of shorter brass life caused by loose primer pockets. Loose primer pockets are most easily and repeatably anticipated by me by measuring the increase in extractor groove diameter. Primers may not fall out with a .001" increase in extractor groove growth, but the load is no good for brass life. Many persons who read this forum think that a scary looking primer is a pressure sign. | |||
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Mike My understanding is that with computers in manufacturing the tolerances in post 1980's rifles are now too close to "trust" the old traditional pressure signs. With a speed to compare alongside the other published load values, maybe one can still feel safe about probable pressures as well. I'm sure you will track case life and other things that would tell more. (Have read your previous posts enough to know you are certainly competent.) Guess I'd back off a full grain and see what changes. Cautiously accurate, Barry _______________________ | |||
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Thanks for the additional info Barry Mike Legistine actu quod scripsi? Never under estimate the internet community's ability to reply to your post with their personal rant about their tangentially related, single occurrence issue. What I have learned on AR, since 2001: 1. The proper answer to: Where is the best place in town to get a steak dinner? is…You should go to Mel's Diner and get the fried chicken. 2. Big game animals can tell the difference between .015 of an inch in diameter, 15 grains of bullet weight, and 150 fps. 3. There is a difference in the performance of two identical projectiles launched at the same velocity if they came from different cartridges. 4. While a double rifle is the perfect DGR, every 375HH bolt gun needs to be modified to carry at least 5 down. 5. While a floor plate and detachable box magazine both use a mechanical latch, only the floor plate latch is reliable. Disregard the fact that every modern military rifle uses a detachable box magazine. 6. The Remington 700 is unreliable regardless of the fact it is the basis of the USMC M40 sniper rifle for 40+ years with no changes to the receiver or extractor and is the choice of more military and law enforcement sniper units than any other rifle. 7. PF actions are not suitable for a DGR and it is irrelevant that the M1, M14, M16, & AK47 which were designed for hunting men that can shoot back are all PF actions. 8. 95 deg F in Africa is different than 95 deg F in TX or CA and that is why you must worry about ammunition temperature in Africa (even though most safaris take place in winter) but not in TX or in CA. 9. The size of a ding in a gun's finish doesn't matter, what matters is whether it’s a safe ding or not. 10. 1 in a row is a trend, 2 in a row is statistically significant, and 3 in a row is an irrefutable fact. 11. Never buy a WSM or RCM cartridge for a safari rifle or your go to rifle in the USA because if they lose your ammo you can't find replacement ammo but don't worry 280 Rem, 338-06, 35 Whelen, and all Weatherby cartridges abound in Africa and back country stores. 12. A well hit animal can run 75 yds. in the open and suddenly drop with no initial blood trail, but the one I shot from 200 yds. away that ran 10 yds. and disappeared into a thicket and was not found was lost because the bullet penciled thru. I am 100% certain of this even though I have no physical evidence. 13. A 300 Win Mag is a 500 yard elk cartridge but a 308 Win is not a 300 yard elk cartridge even though the same bullet is travelling at the same velocity at those respective distances. | |||
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If I actually reach that point, I back off 1 full grain & work w/ that. Seems to have kept my rifles in one piece all these years. LIFE IS NOT A SPECTATOR'S SPORT! | |||
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I think the correct answer to any given rifle/cartridge has to come in terms of a percentage of the case volume... I load .50BMG and 10 full grains of powder is only a few percent of the total load. Likewise, for .223, 10 grains would be 1/2 of the load (just about)... I think that once you have reached a pressure max on a round, given the OAL and other factors, about a 2-3% reduction of charge should take you back into a safer range of pressures (again, dependent on total case volume)... Personally, I 'don't try and run at "max" for any round I load... If you need more power, you get to buy a new rifle in a bigger caliber :-) Personally, whenever I change any major component of a given "safe" load (like primer, projo configuration/projo brand; even if it's the same weight projo, ect..) I always reduce the given load by 10% and do some test firing, just to make sure that something small hasn't compounded and caused an unsafe pressure situation... | |||
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My approach is a little different. I usually have a velocity goal based on load data from several sources and gradually work up to that with the chronograph while checking for accuracy and signs of pressure. If I find an accurate load that reaches my velocity goal without excessive pressure signs, I stop there. If I don't reach the velocity goal because of pressure or accuracy isn't acceptable, I try different powders. Of course, your original velocity goal has to be within reason and you need a chronograph. This usually gets me an accurate load that is a grain or two under max depending on which manuals you are using for reference and the particular rifle. Mike, if you need to use my chronograph, come on down the coast. Have gun- Will travel The value of a trophy is computed directly in terms of personal investment in its acquisition. Robert Ruark | |||
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I designed and buit a chronograph back in the sixties that worked and produced acceptable results. It needed me to do the number crunching but it was worth it. Since that time I never work up loads without it even though it doesn't determine where I stop directly. I start out 10% below book max and move up until I get sub inch accuracy or pressure signs of any sort. Published max loads stop the workup if they are accompanied by near book velocity. Some rifles just max out early and you have to stop well below published max and published max velocity. To me treating published max as anything other than a general top end and not looking to see if you need to stop in the very beginning is just setting up the inevitable disaster. Know that a published max is in a range and just every now and again you run across a rifle where that published max is on the high side of that particular rifle's max. Start low, work up and pay attention. Every step of the way. | |||
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