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Do these primers show signs of high pressure?

Discussion in 'Handloading and Reloading' started by Rmeju, May 27, 2013.

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  1. Rmeju

    Rmeju Member

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    I took my 7mm RM out for the first time yesterday, and the primers looked a bit flat to me when I shot them, so I thought I'd check with all you High Roaders to see what you thought. The first pic shows what they mostly looked like, and the second pic shows a slightly discolored (but not raised) ring around the firing pin dent.

    I shot about 40 rounds, and none of them were close to max (50% were in the middle of the chart, the rest inched up to 3/4s of the way up the chart in groups of 4). The powder is H1000.

    Because none were close to max, the only culprit (if there's even anything to be worried about based on these pics) would be that I loaded them up to be ~0.003" off the lands, +/- 0.002".

    Are these primers ok, or do are they too flat?

    ETA: If they look flat to you, what's the fix? The loads were well under max, so should I just seat a little bit deeper? Also, the cases are not over max length, although many are near max.

    ETA: More precise load data is in post #11. 162gr A-Max bullets over 62.7-65.5 grains of powder. Max speeds of 2754 fps. WLR Mag primers.
     

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    Last edited: May 27, 2013
  2. oneounceload

    oneounceload member

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    They do to me. My 700 BDL had primers like that once with a 'warm' load, never went that high again as extraction was almost impossible
     
  3. Dean1818

    Dean1818 Member

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    They look flat to me...... So yes
     
  4. 243winxb

    243winxb Member

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    The row on the right, the 4 th case down, shows a little flow into the firing pin hole. May not mean anything at all. More load info is needed, bullet, amount of powder, make of magnum primers, brass.
     
  5. Otto

    Otto Member

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    Reading primers is a poor method of detecting over pressures. Flat primers could simply mean too much headspace.
    Was the bolt sticky? Do you own a chronograph?
     
  6. MEHavey

    MEHavey Member

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    Primers are (now) notoriously ill-favored as pressure indicators -- too many variables.

    On the other hand, I see absolutely no hint of any brass flow in the case headstamp
    of your singleton picture. Everything's/the lettering's still sharp. That's Test "1", and you're
    not past ~74-75,000psi

    Reload THAT case five times and if no primer pocket looseness develops, that's Test "2"
    and you're probably Good2Go at ~55,000 - 60,000psi.
     
  7. R.W.Dale

    R.W.Dale Member

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    Short of being pierced primers tell you nothing.

    Just about every variable imaginable has a greater effect on primer appearance than pressure making such appearance guesses just that guesses.

    Is your brass stretching/thinning excessive?

    Are you using published well vetted load data?

    Are your velocities matching or slower than the manual specifies?

    If the answer to those questions is yes my reply is "don't worry about what the primers look like"
     
  8. Walkalong

    Walkalong Moderator

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    They look OK, but as posted, more details would help.
     
  9. steve4102

    steve4102 Member

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    You ask for help identifying pressure signs, but you give this for load info!

    Did it occur to you that the Exact details of the load may be as much help if not more help than your pictures?? "50% in the middle of the chart", what the heck does that mean?
     
  10. ArchAngelCD

    ArchAngelCD Member

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    I'm in they look alright to me camp.
    I'm also in agreement primers are not the way to tell if there's too much pressure in a load.

    MORE INFORMATION IS NEEDED!

    You told us which powder and it's a 7mm Rem Mag but you didn't tell us what weight bullet and which primers you're using. With most bullets in the 7mm RM the powder charges are large and should be set off by a Magnum primer. If you're not using a magnum primer you should be, IMO of course.

    Please give us more information so we can give you a better informed opinion.
     
  11. Rmeju

    Rmeju Member

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    Thanks for all your help.

    Here is the additional data requested. Primers are Win LR Mag. 162gr A-Max. The first 20 rounds were loaded with 62.7gr of H1000. Average velocity 2675, which is a hair under the published data in my book (Hornady) for that load. I never got above 2760 with any of the loads.

    Max for that bullet in my book is 68.5gr of H1000, at 3000 fps. Hope that helps.
     
    Last edited: May 28, 2013
  12. Conservidave

    Conservidave Member

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    You ask for help identifying pressure signs, but you give this for load info!

    Did it occur to you that the Exact details of the load may be as much help if not more help than your pictures?? "50% in the middle of the chart", what the heck does that mean?


    Did it occur to you that the original question was " Do these primers show signs of high pressure"... nothing more, nothing less. If you would like more information about the load you should simply ask for it, period.
     
  13. steve4102

    steve4102 Member

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    It did! And reading primers is A kin to reading tea leaves ! Especially when most if not all pertinent data is omitted.
     
  14. steve4102

    steve4102 Member

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    Nope, not a lot of help without the bullet and bullet weight.
     
  15. oldreloader

    oldreloader Member

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    I'm with the "look ok to me group". I started loading back in the 1960's when we did use primers for a pressure sign and we didn't have anywhere near the equipment available that some do now..
     
  16. Rmeju

    Rmeju Member

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    I posted this info in post #11. I have now reposted it in the OP, so it is easier to find.
     
  17. ArchAngelCD

    ArchAngelCD Member

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    From the numbers he's using that come right out of the Hornady manual he's using a 162gr Hornady bullet.

    I would not expect to achieve the velocities listed in the manual because they are generated under lab conditions and usually with a longer test barrel.

    From the velocities you are reporting it seems like you probably are not generation the high pressures you originally asked about. Why are you increasing your powder charge if you are worried about pressure? You are speaking about pressure and velocity but you never mentioned accuracy. Just because a load manual tells you you can use xx amount of powder doesn't mean you are required to. Most times the max charge does not deliver the best accuracy and the best accuracy is what you should be trying to achieve. I would not sacrifice accuracy for a slight increase in velocity. That game animal will be no deader if you hit it with a 162gr bullet @2700 fps or @2725 fps!!! :rolleyes:
     
  18. Rmeju

    Rmeju Member

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    Just using it for paper punching. No hunting in the foreseeable future.

    Yesterday was the first day I took the rifle out, so I was testing out a few different loads to see how they shot. Most were sub-MOA with 4 shot groups, but some loads were clearly better than others. I didn't go all the way up to the top of what I loaded, since I was limited on time and figured I should ask around since the primers looked flat. I guess that's not the preferred method of detecting high pressure anymore, or so it seems.

    Most of the loading I do is for volume (pistol, bulk semi-auto), so I normally just load very low and don't worry about pressure. This was a target rifle though, and so I'm messing around with working up a load. That's why I was poking around with various charges. I just didn't want to shoot the ones higher up the ladder if I was having pressure problems. Sounds like I don't.

    I guess I still don't know how to tell if I'm having pressure problems though. What is the load data telling you guys that it's not telling me? Is there a formula I don't know about?
     
  19. Jesse Heywood

    Jesse Heywood Member

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    No magic formulas. Reading primers for pressure was disproven with the advent of modern testing equipment, measuring chamber pressure over the entire firing cycle instead of the older method that only measured the maximum pressure reached. What is used by reloaders is the result of the improved testing, comparing published load data with the results obtained by velocity reading and accuracy. It still involves some guesswork, but with the newer data available the estimation is based on far superior data than reading primers.
     
  20. gamestalker

    gamestalker member

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    I see a number of primers in the pics that look as though they are protruding from the pocket. Those to me indicate a possible low pressure situation. And the rest don't really exhibit high pressures in my opinion, but they do look inconsistent in appearance. The rather erratic appearances lead me to believe you may be seeing low pressure signs, rather than high. But in all honesty, I don't rely on primers for pressure evaluation other than using them in addition to other factors. When I work up a load in my 7 mags and have reached the limit, the primers will of course exhibit filled pockets, evidence of top hat expansion, and cratering around the firing pin strike. I'm not seeing any of that going on here.

    I don't have a lot of experience with H1000 in the 7 mag, other cartridges, but not a lot with 7 mag.. That said, I'm uncertain if the chrony information you provided us, would be consistent with what's to be expected with H1000 using a mid range load. I know with RL22 I can expect to easily obtain 3000 to 3100 fps range with room to spare, in terms of pressures v.s. velocities with a bullet weight consistent of that which you are using.

    Another element that can cause pressure issues is how far you are off the lands. this alone can elevate pressure well beyond acceptable with loads that would normally be acceptable. As well, if you had seated that close to the lands as indicated .003" - .002" without a ton of experience doing so, it is possible to get some significantly closer, or actually into the lands, while others may be considerably further off the lands, thus producing inconsistent primer expansion.

    So how was the bolt lift? What were the specifics of the charge? And were you using an accurate method of measuring OAL off the olgive, to obtain those seating depths? And did you measure each charge using a scale?

    GS
     
  21. ArchAngelCD

    ArchAngelCD Member

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    Sir, the bullet weight was not in Post #11 until you did and edit and added it later on. I read that post more than once and it was not there. No reason to make things up especially when we are all trying to help you.

    Now, please explain to me why you are using such a powerful cartridge for killing paper @100 yards? Such a heavy hitter is even too much for Deer, including Mule Deer IMO. If I were loading a 7mm RM for target shooting I would download the ammo. Many shooters who have a 300 Win Mag do the same and download their ammo to 30-06 power.

    I would switch to a Hornady 162gr BTHP Match bullet and use a starting charge of a faster powder like 4350, 4831 or even Hybrid-100V. Sending that bullet out of the barrel @2500 fps will make your range shooting much more pleasant IMO and with the reduced recoil you just might increase your accuracy too... You might even want to shoot a Sierra 150gr MatchKing bullet instead and load even lighter similar to the 280 Remington. Just a few thoughts you might consider.
     
  22. steve4102

    steve4102 Member

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    Light loads of Slow powders have been blamed for more than one KB over the years. According to Hodgdon your loads are below Minimum, not a good place to be with slow powders.

    Hodgdon data lists 67gr as Minimum.

    Code:
     162 GR. HDY SPBT 	Hodgdon 	H1000 	.284" 	3.290" 	67.0 	2800 	45,400 CUP 	70.0 	2905 	49,600 CUP  
    http://data.hodgdon.com/cartridge_load.asp
     
  23. ArchAngelCD

    ArchAngelCD Member

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    While I agree with your post Hornady's load data is very different than that supplied by Hodgdon. Hornady #9 with their 162gr A-Max bullet lists a charge range of 56.8gr to 68.5gr H1000 in the 7mm Rem Mag. It's amazing how very different some of the data out there is. I wish someone could enlighten me as to how both data sources are safe??? With just over a 10gr difference in minimum load that's a little hard to understand, no? (at least the high side is not so different)
     
  24. hang fire

    hang fire Member

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    Same here. Although primers are a poor indicator of pressure, I get real concerned when a flattened primer looks to be milled into it's pocket.
     
  25. Robert101

    Robert101 Member

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    I agree with HangF. I realize this is a 7mm mag. Primers may look like that due to this cartridge. If it were a 308 with primers looking like that, I would look for other case stretching issues.
     
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