Primers showing overpressure--- But why?

Discussion in 'The Ammo & Reloading Forum' started by deerstuffer, Oct 22, 2010.

  1. deerstuffer

    deerstuffer New Member

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    Currently loading some 25-06 for the first time (new rifle). I am using 100gr Nosler b tips and test firing for that sweet load from 40.0 grains to 44.0 of IMR
    3031. My question, all but the lowest wt. powder charge is showing some signs of overpressure with Winchester primers flattening and rimming a small amount. All equipment seems to be fine,cases seem fine, loads are well within safe charts and recoil and noise seem fine. Could Winchester primers that are brass be a little soft or have I got something going on her that I haven't thought about any help out there? Thanks Guys
  2. JohnTheCalifornian

    JohnTheCalifornian Member

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    On IMR's site, there is no data using 3031 for the 25-06. Although I did find data for 3031 in my Lee book, which shows a starting point of 40 grains and a never exceed charge of 45 grains for 100 grain jacketed bullets.

    How are you measuring the charges? I would consider double and triple checking to make sure your scale is not throwing out the wrong charges.

    How deep are you seating the bullet into the case? Too deep and you decrease the case capacity and can cause higher pressures.

    Can you post pictures of the cases with the head showing so we can see the primers?

    I can bet money others will post with other problems/solutions and together can help you to solve this mystery.

    John
  3. steve4102

    steve4102 Former Guest

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    Primers are not the best indication of over pressure. Is this new brass or fired sized brass? BTW, why 3031? It's pretty fast for the 25-06 and there are much better powders out there.
  4. deerstuffer

    deerstuffer New Member

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    Guys, for the seating depth I am using the method of closing the bolt and trying to get the depth to almost the lans of the rifling. For that reason I feel it is long if anything but not to long to cause overpressure by touching the lans. And my brass is once fired then I bought it 100 at a time. The reason for 3031 was economics, in that it is a pretty good overall powder for much of my reloading. I picked it because Hodgen charts on line showed it to be a moderate burn powder, is this not true?
  5. Lee C.

    Lee C. New Member

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    I went to the hodgen loading page and didn't see any loads for 3031 powder and 100gr bullet. My oldest son shoots a 25-06 with IMR4350 and 100gr bullets with no trouble at all with the load. It would be nice to fine one powder to do it all. But then agine it would take alot of the fun out of looking for that sweet load we all look for.
  6. The_Rifleman

    The_Rifleman New Member

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    Yes... My reloading manual lists much slower burning powders for that bullet weight in the 25-06.

    I usually get pressure signs on the primer before anywhere else.
  7. LDBennett

    LDBennett Active Member

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    Some of the methods I have seen for determining where exactly the rifling starts in the barrel are not very accurate. And in fact some methods get the bullet into the lands. When that happens the bullet is delayed in starting its motion down the barrel which gives time for the pressures to build more than if the bullet has a run on the rifling. It may be that the bullets are really touching the rifling and delaying there too long creating higher pressures.

    Then there is your powder choice. On the Hodgdon Reloading data online they use powders much slower than your 3031, like Win 760, H414, H4831, etc. Take a look at:

    http://data.hodgdon.com/main_menu.asp

    LDBennett

    Bullet Weight (Gr.)/Manufacturer/Powder/Bullet Diam./C.O.L./Grs./Vel. (ft/s)/Pressure/Grs./Vel. (ft/s)/Pressure

    100 GR. NOS PART Hodgdon H1000 .257" 3.200" 56.0 3055 44,600 CUP 59.7C 3212 50,700 CUP

    100 GR. NOS PART IMR IMR 7828 SSC .257" 3.200" 53.0 2940 40,700 CUP 57.2C 3203 51,300 CUP

    100 GR. NOS PART Winchester Supreme 780 .257" 3.200" 52.2 3074 45,400 CUP 55.5 3229 50,000 CUP

    100 GR. NOS PART Hodgdon H4831 .257" 3.200" 51.0 3025 46,800 CUP 54.3 3172 51,400 CUP

    100 GR. NOS PART Hodgdon Hybrid 100V .257" 3.200" 48.0 3034 44,200 CUP 52.5 3295 51,800 CUP

    100 GR. NOS PART IMR IMR 4831 .257" 3.200" 49.0 2981 41,700 CUP 54.0 3233 51,400 CUP

    100 GR. NOS PART Hodgdon H4350 .257" 3.200" 47.0 3038 47,800 CUP 50.0 3155 51,500 CUP

    100 GR. NOS PART Hodgdon H414 .257" 3.200" 42.0 2843 44,600 CUP 47.0 3059 50,700 CUP

    100 GR. NOS PART IMR IMR 4350 .257" 3.200" 48.0 2975 43,200 CUP 52.8 3257 51,200 CUP

    100 GR. NOS PART Winchester 760 .257" 3.200" 42.0 2843 44,600 CUP 47.0 3059 50,700 CUP

    100 GR. NOS PART IMR IMR 4007 SSC .257" 3.200" 46.0 2992 42,900 CUP 50.8 3256 51,100 CUP

    100 GR. NOS PART Hodgdon Varget .257" 3.200" 41.0 2974 45,600 CUP 44.0 3125 51,400 CUP

    100 GR. NOS PART IMR IMR 4064 .257" 3.200" 40.0 2904 40,400 CUP 44.0 3122 50,800 CUP

    100 GR. NOS PART IMR IMR 4895 .257" 3.200" 42.0 3009 46,000 CUP 45.3 3155 50,400 CUP

    100 GR. NOS PART Hodgdon H4895 .257" 3.200" 40.0 2921 44,200 CUP 43.0 3072 51,000 CUP

    100 GR. NOS PART IMR Trail Boss .257" 3.200" 13.4 1454 25,500 PSI 19.2 1712 30,600 PSI
  8. Bindernut

    Bindernut Well-Known Member

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    Like the others, I would also suggest that 3031 is faster than what I would recommend using in the .25-06.
    Not sure where you found data for 3031 in the .25-06, I don't have any loads for that powder in the manuals I've got...but I don't have em all either.
    I would also recommend a slower powder. If you're possibly looking to load lighter bullets than the 100gr I'd maybe try IMR4350, H4350, or RL-19. If you're looking to loader 100gr and heavier bullets (117-120gr) I'd recommend H4831, IMR4831, or RL-22.

    My personal favorite powder for the .25-06 for both 100gr and 117-120gr bullets is H4831, but I've used IMR4350, RL-19, and RL-22 with good results. Yes, I'm a fan of sticking with powders on the slower end of the recommended range for most all of my rifle cartridges.

    A slower powder is almost always bulkier and will take up more of the empty space inside the case. That's called load density in case you've seen that percentage in any of your manuals.
    The overall volume of a .25-06 case is roughly 65grs(water). Using your 40-44gr 3031 loads, you're only using about 66% of the case capacity. That much unused space inside the cartridge case has been known to cause some erratic powder ignition problems due to inconsistent powder placement inside the case. If you've got too much airspace in the case, the primer flash can ignite more of the powder at once, instead of a nice even burn from rear to front as you'd see in a higher-density load. This can make for a high pressure spike upon ignition compared to a higher-density load...coupled with a fast burning powder you could very well have a very high initial pressure situation inside the case.
    Without a pressure test rig, there's no real way to see what pressure your loads are at...but as Rifleman suggests, the primer flattening/cratering is usually one of the first signs of high pressure.

    LD's mention of seating on the lands (instead of just short of) will also cause high pressures. Double check your measurement and/or seat the bullets a bit deeper to see if this might also be the cause or part of the cause of your problem.
    Last edited: Oct 23, 2010
  9. JLA

    JLA Well-Known Member

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    IMR3031 is too fast for the 25-06 with that heavy bullet, IMR4350 is your ideal choice IMO...
  10. JLA

    JLA Well-Known Member

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    ;) fixt it for ya binder
  11. deerstuffer

    deerstuffer New Member

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    To all that responded Thank-You so much. That is why this site is so good now I have got knowlege to use. But primarily I need some new powder and ilt sounds like 4350 will be it and then back to the range. Thx all Chris
  12. muddober

    muddober Active Member

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    Chris, while I agree that 3031 is not the powder you should be using and 4350being the far better choice, only Bindernut in my opinion started to explain the true causation of your high pressures signs and then lost it with his last paragraph. Your high pressure signs in my opinion have nothing to do with the placement of the bullet in relationship to the rifling. I will attempt to explain both. Too much air space in the case can cause fatal results because air will compress and it compresses much faster than the bullet can move down the barrel. Progressive burning powders are just that; meaning they don't explode but rather they burn at a rate depending first on their designed composition and second the environment they are contained in. The way they work is the faster they burn the more heat and pressure they make, the more heat and pressure they make the faster they burn. With a loading that utilizes most of the space of case thereby creating little air as Bidernut suggested, the more consistent the powder works as designed. When any powder burns it doesn't care if it is working by making pressure by the resistance of a bullet being push down the barrel, the resistance of the casing of a bomb or the resistance through the compressing of air. Of the three, the air will compress the fastest to the point that it will compress so fast allowing the rise in pressure to dangerous levels before the bullet can move down the barrel relieving it. The powder even when compressing just air has found the proper environment by which to make it work as it was intended. Thank God seeing the pressure signs you did, didn't cause you reduce your loads using even less 3031, because you could have made a bomb out of your gun. Several years ago a guy over the hill from me in California made up some light loads of 4064 for his wife in a 25-06, which is very similar to 3031. Her first shot killed her instantly when the action exploded and the bullet never left the case all the way.

    Now to the issue of crimp and placement of the bullet in relation to seeing pressure. P.O. Ackley did some testing many years ago whereby he made up a pressure test gun chambered in 30-06 somewhat like Bidernut described. Ackley made up some loads using as I recall a 150 grain .308 bullets and fired them recording the pressures. He then rechambered the barrel so it would accept a .323 (8mm), so essentially he made a 8mm-06 and using the same powder charge with a 150 grain .323 bullet fired the gun again thereby pushing the .323 bullet down the .308 barrel. He saw NO additional pressure signs in his equipment. He then rechamberd it again to accept .358 150 grain bullet and actually saw a slight decrees in pressure. I think I know why he saw less pressure with the .358 bullet but I have probably bored you enough. Ackley reasoned and I believe correctly so, that because the bullet only had to move a half inch before it was squeezed down to .308 all happening long before the powder was able to do its work making pressure. My point is and I believe it to be well founded that if squeezing a much larger bullet down to a smaller bore doesn't raise pressures, bullet placement or a heavy crimp would have even less of an effect on pressure.

    The little lady called me to dinner so I came back to edit a bit.

    Ron
    Last edited: Oct 23, 2010
  13. LDBennett

    LDBennett Active Member

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    deerstuffer:

    In Hornady's 6th edition of their Reloading Manual on page 26 they show the very situation of the bullet touching the rifling. They say that with no run on the rifling it takes greater pressure to force the bullet into the rifling. They also say that the resulting pressure is also more rapid rising, and excessive, and the bullet velocity is higher than normal. They state that the load should be reduced by a couple of grains to produce normal velocities and pressures if you insist on letting the bullet touch the rifling.

    A reloader can believe anything he wants about what produces different forms of excessive pressure (detonation, too much air space, or whatever). I choose to believe what Hornady states in their reloading manual. They have a lot more experience than I do (or most others that come here) in anything to do with reloading.

    Detonation MAY be a real problem but real proof has been very hard to come by (but that does not mean it does not exist!). The fact is that 3031 is a poor choice for 25-06. Slower powders are probably a better choice but stick to what is in manuals, for safety's sake. If you want to make the bullet just barely touch the rifling or a couple of thousandths just off the rifling (as I often do) then start at the starting load and work up from there.

    LDBennett
  14. Bindernut

    Bindernut Well-Known Member

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    Very good job explaining the low density load situation mud. Better than I could put into words!
    I've never personally seen the consequences of light/fast/low-density loads in a rifle, but I've seen a few stretched/cracked actions and empty cases showing the aftermath. That's one reason why I've always tended to stick with slower powders for higher load denisty.

    I've also dug into Ackley's studies on the seating on the lands (or oversize bullet) stuff too. But I have had situations where seating on the lands instead of with a bit of freebore can cause higher pressures though too...in my case I did a sloppy job of setting up my seater die when I did some .243 reloads a few years ago. I forgot to readjust the seater stem when I switched bullets/loads and I had a bunch of long-loaded rounds. The very first shot overpressured enough that the primer pocket stretched enough so that the primer completely fell out of the empty case. The only thing different from a proven load in that rifle was the seating length. I still believe that in certain situations, this can also cause high pressures. I don't exactly care to go out and try to repeat the experiment though...I'll leave it up to the guys with pressure rigs. :)
  15. muddober

    muddober Active Member

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    Bindernut:

    Trust me I believe you, even though I have not had the problem but now I am going to play with it a bit by changing the over all length of what I consider close to max loads and see if I can find pressure variances. I do not have a pressure test barrel so I will have to depend on measuring the back of the case for stretch and watch my primers. I will let you know my results.

    I am glad you are familiar with what P.O. Ackley did, that tells me you are no neophyte at this.

    Ron
    Last edited: Oct 25, 2010
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