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Flat primers
Thoughts?
I got some time at the range today. Father's Day present. What can I say, I have a great wife. At any rate, I had some development loads for my CTR 260. I used H4350 for a few 5 round test batches. I started seeing flat primers at 44 grains. Also saw flat primers at 44.5 grains. The 44.5 grain is at book max. I did not have sticky bolt and did not see any over pressure signs on the cases. Is this worrisome? I Chronoed each round and was very happy to see 2725 and 2758 fps respectively. Both of the aforementioned loads shot very well at 100 yards. I can cover them with a penny, aside from one shot that I pulled! Should I be concerned that I had flat primers? What is the danger with this? I would really like to make this my new “go to” load but only if I am not burning up my barrel or worse yet, creating bodily harm. Let me know your thoughts. As always, thanks for your help.
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8 Replies
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Flat primers are not necessarily an indication of excessive pressures. Different primer brands/types are differently hard. You might try magnum primers (backing off the powder and working back up), or a brand that is known for tougher primer cups. If I find the article I'm thinking of I will post a link here.
http://bulletin.accurateshooter.com/?s=soft+hard+primer+cups&submit=Search
Keep an eye out for other pressure signs like excessive web expansion, loosening primer pockets and marks on the cartridge base (polished spots, ejector pin marks and engraving). It is possible that you are getting high pressures, even though the load was published as safe. Tight chambers, bullets seated into the lands, bullets seated deeply into the cases, out of spec powder or primers, high temps, over long cases and probably many other things could aggravate a cartridge's pressure.
Good luck and keep us posted,
-Eric -
Great response Eric,…good info.
I've switched all my reloading primers to CCI for pretty much the same issues you are experiencing.
If you haven't tried them give them a shot.All small caliber rifles – Br4
All large caliber rifles – Br2
300wsm – 250 magnumIts solved my problems with max loads…not saying they are the best, but I like them.
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Excellent info gents. I have been using Federal 210 match primers with new Lapua brass. Dog, I have a bunch of the CCI primers. Ill load some up to see if that helps. Thanks.
As far as markings on the cases go, I did not see anything unusual. I have been seating the hornady 143 grain eldx to a 2.90 coal. I used the hornady coal measurement tool to get a baseline. I know that this tool is not exact. I believe I have backed off .40 from my measurement. Maybe I am seating the pills to far out? Thoughts? I do know that my 260 really shoots well at that coal with that pill. I have tried .05 increments starting from 2.85 up to 3.05. I believe that the 3.05 coal rounds were touching the lands. They performed badly, by the way. I also shot test loads with reloader 19 and h4831sc at the same coal, the primers looked great.
Eric, what does excessive web expansion mean? Sorry for my ignorance.
Another factor could be the heat as Eric pointed out. It was a hot and humid 90 degrees in Wisconsin yesterday. I tried to keep my rounds in the shade. I also let the rifle cool for at least 10 minutes in between 5 round test batches. This is my first time using Hodgon H4350 so I am not sure how the heat impacts that powder/primer combination. I guess there could be a few factors in play here.
I should be satisfied with the 43.5 grain load that shot 2700 fps. It's a vast improvement over the 2570 fps I was getting with h4831sc. But hey, if I can get to 2750 fps with a 20 in barrel and pills that have a .610 BC, well that would just make me smile.
Thanks again!! Really appreciate all of the advice and suggestions. Let me know if you have any other thoughts.
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Good question BB,
The web is the bottom of the inside of the case and excessive expansion of the area just ahead of that point is a clear sign of high pressures. The spot I think of as the web area for measuring purposes is where the belt would be if the case was a belted magnum i.e. just a bit in front of the extractor groove. I can't give you an exact location or how much expansion is acceptable since it depends on some variables, but in general if you load the same case (or very similar cases) with progressively hotter loads you will reach a load where the diameter of the fired case (measured just in front of the web) will increase significantly more than it did on the previous lighter loads. I would expect some of the other pressure signs to show up before this indicator becomes noticeable. A good rule of thumb is to not focus on any one type of pressure sign – lots of variables so if you have 2 high pressure indicators, chances are your load is too stout and at the very least your case life will be short.
(Clarification edit) I re-read this and it might have sounded like I was recommending that you should wait until you see 2 pressure signs – not what I meant- I was suggesting that you look for all the signs and not use one criterion only i.e. don't ignore loose pockets, cratered primers and ejector marks because your waiting for the web expansion indicator!I had a 25-06 load with nozler partitions that started to blow primers on every other shot or so – I was a new reloader (back in the early '80s) and since the load was published I assumed the loads were safe. I don't know for sure (now) what the problem was but I retired the load. As it turns out my firing pin spring was weak and probably contributing to the piercing but there was no question the loads were warm. Anyway, enjoy researching the subject and here are some good articles on excess pressure and reading your cases: http://bulletin.accurateshooter.com/2007/06/detecting-excessive-pressure-in-your-cases/
http://bulletin.accurateshooter.com/2016/03/case-diagnostics-find-the-flaws-in-your-cases/Regarding high temps.
H4350 is one of the most temp stable powders available – better in a recent test than the new IMR Enduron 4451 (4166?) powder advertised as temperature insensitive. There will be some pressure increase even with H4350 due to higher temps but is not likely to be the primary source of your pressure issue given the conditions you mention.Good shooting, -Eric
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Awesome. Thanks for the input and the links. Much appreciated.
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Just as an FYI…. I load my 260 CTR with 44.6gr of H4350, topped with a 139gr Scenar, LaPua brass@ 2.850 OAL & CCI LR primers. This load has pretty much consistently yielded 2742 fps since the get-go…
Occasionally I'll get some over pressure signs ( ejector pin marks, loose primer pockets) but never had any flattened primers. So far I've gotten good brass life with this load…(10x re-loaded) and when the brass does go bad, it's always a split or crack in the neck of the case. I'm at 2,270 rounds through the gun now and as I'm having to now chase the lands with my OAL, I'm thinking a new barrel isn't too far off in the gun's future. The next barrel will be longer… 🙂 -
Thanks for the info Rancho. I have not been able to get back out but I have loaded up more test loads with CCI primers. Thinking that will help. I looked back through my brass, which was virgin Lapua, and did not find extractor marks, web esxpansion, cracks, gas leaks around the primers or loose primer pockets. I wonder if the long coal I am using along with the thicker Lapua brass has added more chamber pressure. Or it's just the primers. I won't know until I get back out to be range. I agree with you on the longer barrel. If my CTR didn't shoot as well as it does, the barrel would have beenreplaced with a 26 in Bartlein a while ago.
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Thought I would post an update on this. I spent a bit of time reading articles and forums about the primer issues I was seeing. Again, thanks for the help!! I read in a few places that folks were having issues with virgin Lapua brass showing flat primer signs and other over pressure signs. The reccomendation was to full length size the virgin brass. I had a few virgin cases left so I decided to test out this theory. I resized 5 cases and loaded them with the same load and primer as before. I also loaded 5 virgin cases, again with the same load and primer. I was able to get to the range last week. Temps were lower than when I had the first issues but it was still over 80 degrees. I did not have flat primers on the 5 resized cases. I did have flat primers on 4 out of the 5 virgin cases. Although, not as flat as the first day. So, I found my issue. The question is, why? My thought is that Lapua brass is thicker and it fills up the chamber. But I don't know that full length sizing reduces the outside diameter of the case. If anyone can explain, I'm always willing to learn.
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