I was workin on a load today for my 270 win. 150gr Partitions. COL of 3.300 and I was using 1.6 grains less than max of IMR4350, so I was using 50 grains, checked the primers out and they were flattened, and I was a little concerned, should I be? I am using winchester primers. Can someone show me a pics of a flattend primer.

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checked the primers out and they were flattened, and I was a little concerned, should I be? I

Yes...in and of itself this may be a sign of pressure and needs to be heeded.

See Steve's pages for photos of flattened primers.

Check the brass length and other factors that might be a cause of pressure.

50 grains of IMR 4350 should be ok.....but when you have flat primers IMOwe stop and ask why.....it might be ok....but I'd like to look it all over carefully.

maybe I will take a pic and then somoene could give there input, its not terribly flattend but I'm not sure. pic to come soon.

There can be a lot of reasons, but first question that comes to mind is what brand of case?

DIfferent brands of cases have different powder capicites. Even differnt lots between the same manufacturer can vary, usually between old and new manufacture lots.

If you are resizing military 06 brass it has a much smaller interanl case capaicity than new manufactured WIn and Rem brass.

Once you know what your internal case capicity is, you can adjust your powder loads.

Another item is are you using Mag primers? These can cause higher pressures if your manual did development with standard primers.

A last place to check is what length was your brass, long cases cause all sorts of problems.

I am using non-magnum primers and remington brass trimmed to 2.530 and OAL 3.300. Are these cratered?

Flat primers by them self don`t mean much. The primers can flatten from more then just high pressure, excessive headspace comes to mind as the first culprit. I`d check for other problems such as hard extraction, sticky bolt lift, cronograph readings in excess of what they should be, ect.

I spruced up the photo....and these primers don't look too bad at all.IMO

The second case starting from the right looks like it has a really flat primer and all of them are cratered.

Do you get any of these signs with standard factory ammo? If not I would say you are over max but I'm no expert.

Enigma

If I see them clearly, they don't look very flattened to me. Have you shot any factory loads in this rifle? What it looks like to me is the firing pin channel in the bolt is slightly oversized so that the pin is causing a cratered look in the primer. IMO, if this is the only sign you are finding I wouldn't worry about it and fine tune your load but watch for other pressure signs that were mentioned in an earlier post. If you truly believe this is a clear sign of excess pressure you might consider using a powder with a slower burn rate.

I'd say they are all cratered and the one in the center looks like The P in R P got a little wipe out How did the bolt handle lift? Atleast on one it looks like you got some rubbing. NO here we've all been there. Now ,however you should try to find out why. roger

From looking at you pics your primers are not consistant in seating depth. Thats an issue you need to sort out. Whether its causing your flat primers...maybe. These are all seated too deep, and classic pressure signs would have these flattened out to the base of the rim, flattened out against your boltface. Your case length should be right.

I would load up a couple more backing out on your primer seating depth and look at them, I suspect these will look different.

Your primers are also telling a tale. Notice that these are all cupped slightly on one side? Your bolt face isn't square. Not a big issue on a hunting rifle ( 270 win ) on a benchrest gun I would be all over that.

They're fine. Don't worry about it.

I own a Ruger M-77 KMII in 7.62 X 39 m/m and with a reloading of 25.0 grs of IMR-4198 with a .310" 123 grain SPT bullet I receive flat looking primers too. To solve this I "necksize" only and this eliminates the flatten fired primers. Interesting enough; I've found the Ruger M-77 MKII in this caliber has a very long throat. If one uses a regular .308" bullet, then necksizine is a MUST or you wil experience the following: a misfire or backed-out primer. I guess when Ruger made this rifle they made the chamber so one could fire BOTH .308" & .310" bullets. I have read the bore dia. on this particular rifle is .309".

DRS: The throat size is irrelavent; it is the location of the chamber's shoulder that establishs the "headspace" on this cartridge. If the length of the chamber from the face of the bolt to the datum point on the shoulder is significantly longer than the corresponding length of the loaded ammunition you are using, then you have "excessive headspace". This may be from EITHER the chamber or the ammunition being "out of spec". The solution, as you have found, is not to set the shoulder of the case back after firing, thus you have a case that is a perfectly dimensioned for your rifle's chamber.

A common manifestation of "excessive headspace" in the fired case is the flattened appearance of the primer. This occurs because the primer backs out of the pocket upon firing until it rests against the bolt face, after which the case stretches under building chamber pressure untile the case head is forced back against the bolt face. As the case head moves rearward, it "reseats" the primer, but the rear portion of the primer "spreads" against the bolt face and creates an extremely flattened appearance.

I can't see the photos of the primers in question, so can't comment on what may be going on there.

Those cases do not have flat primers, they have cratered primers but I think that is because the rifles firing pin is too long or the firing pin need bushing...

I see a couple with extractor marks barely showing, I would say some of those rounds are fine with the fouth one max...the only thing that would make me drop back a grain is the extractor marks (shiny spot on case head)....

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Originally posted by Stonecreek:
DRS: The throat size is irrelavent; it is the location of the chamber's shoulder that establishs the "headspace" on this cartridge. If the length of the chamber from the face of the bolt to the datum point on the shoulder is significantly longer than the corresponding length of the loaded ammunition you are using, then you have "excessive headspace". This may be from EITHER the chamber or the ammunition being "out of spec". The solution, as you have found, is not to set the shoulder of the case back after firing, thus you have a case that is a perfectly dimensioned for your rifle's chamber.

I was wondering since the 7.62 X 39 m/m cartridge was made for semi-auto's the factory loaded cartridges might be sized a little smaller to accomadate smoother feeding. You're right that necksizing, inthat I've created a cartridge that is correct for my Rifle's chamber. Since I've had this little Ruger, I've found out that the 7.62 X 39 m/m is a little fussy to work-up reloads. I've found the BEST powders to use are IMR-4198 and WW-680 (Which is unavailable now) other powders available should work well also but I haven't had a chance to experiment.

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Originally posted by Ranger66:
I was workin on a load today for my 270 win. 150gr Partitions. COL of 3.300 and I was using 1.6 grains less than max of IMR4350, so I was using 50 grains, checked the primers out and they were flattened, and I was a little concerned, should I be? I am using winchester primers. Can someone show me a pics of a flattend primer.

Primers can appear flattened by several causes besides excessive pressures. If your primer pockets are still tight after using that load, and you can get a number of reloads out of those cases without the primer pockets getting too loose, the load is O.K. (My most accurate 150-grain Partition load in the .270 uses 53.5 grains of IMR 4350 in WW cases with Fed. 210 primers, and it is not maximum in my rifles......

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Originally posted by Ranger66:
I am using non-magnum primers and remington brass trimmed to 2.530 and OAL 3.300. Are these cratered?

Just looked at your pics - those are not really flattened primers-the edges are still nice and rounded.......

Try a different primer. Try CCI or Federals. I've experience problems in seating Winchester primers and their fit in the pocket. I've had loose primers with Winchesters and even seen where the primers came off after having been fired then I used a different primer and never had the problem again.

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Originally posted by DRS:
I was wondering since the 7.62 X 39 m/m cartridge was made for semi-auto's the factory loaded cartridges might be sized a little smaller to accomadate smoother feeding.

Well, that's not out of the question.

All cartridges have a set of SAAMI specs, and those specs are, in part, based on the cartridge's design parameters and intended uses. Manufacturers don't EVER want their ammuntion to fail to chamber in ANY rifle, so they tend to build their ammo near the minimum dimensional specifications. Just the opposite is true with rifle manufacturers, who make their chambers on the large side (starting with a chambering reamer that is at maximum dimensions also means you get more chambers out of it before it is worn down below minimums.) This is especially true with calibers that are primarily intended for autoloaders, due to the inherent issues of feeding and functioning.

As a result of these factors, I would expect almost any factory 7.62 x 39 rifle to exhibit headspace with factory loads that most experienced riflemen would regard as being "more than desireable". I suppose you could only call headspace "excessive" if the cartridges sometimes failed to fire. At any rate, resizing your fired brass of any caliber only enough to assure positive, low resistance chambering (neck or partial sizing) is always a good idea with a bolt action or other rifle that provides a strong camming action when chambering the round.

Not my pic but here is a great pic showing flattened primers.