Author Topic: Primers pushing out? What would cause this?  (Read 9010 times)

Joel

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Primers pushing out? What would cause this?
« on: October 27, 2013, 05:15:20 PM »
A friend gave me some .44 Spl brass he'd sized and deprimed years ago with the warning that he thought most of the primers were bad. Rather than take the chance of loading a bunch of duds I decided to snap the primers in my revolver before processing the brass for reloading.

The first primer snapped just fine, and then either bulged or backed out of the pocket and bound up the action. I got it clear, closed the cylinder and snapped the next one. Which did the same thing.

I dug up a .44 insert for a 12-gauge that's been lying around and snapped all the rest. And every one of the primers fired, and every one bulged enough to have locked up a revolver's action.

I'm not a big reloading expert but have handloaded for pistols off and on for decades and have never seen this. But then I haven't wasted many primers in this fashion, so maybe it's common for some reason and I just never noticed. Any ideas what would have caused it? I can't believe all fifty primer pockets are oversized...

Offline mxitman

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Re: Primers pushing out? What would cause this?
« Reply #1 on: October 27, 2013, 09:44:56 PM »
Not sure, but I had a box of 357 Mag from "*******" do exactly that about 5 years ago, was brand new ammo and 42 out of 50 rounds bulged out... I had just bought the gun and it was the first rounds fired so I thought the gun was junk...only to find out it was the ammo. I called them and they paid me to ship them the rounds and then they gave me a huge case of ammo for the trouble and sign a NDA that stated I promised not to say who they are ;)

Offline Mortblanc

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Re: Primers pushing out? What would cause this?
« Reply #2 on: October 28, 2013, 06:58:08 AM »
A friend gave me some .44 Spl brass he'd sized and deprimed years ago with the warning that he thought most of the primers were bad. Rather than take the chance of loading a bunch of duds I decided to snap the primers in my revolver before processing the brass for reloading.

The first primer snapped just fine, and then either bulged or backed out of the pocket and bound up the action. I got it clear, closed the cylinder and snapped the next one. Which did the same thing.

I dug up a .44 insert for a 12-gauge that's been lying around and snapped all the rest. And every one of the primers fired, and every one bulged enough to have locked up a revolver's action.

I'm not a big reloading expert but have handloaded for pistols off and on for decades and have never seen this. But then I haven't wasted many primers in this fashion, so maybe it's common for some reason and I just never noticed. Any ideas what would have caused it? I can't believe all fifty primer pockets are oversized...

This is common and expected when firing empty primed cases.  The primers will back out almost every time. 

When building very low end reduced loads, or wax bullet loads, I have seen times when I had to drill out the flash holes to prevent the primers backing out.  Then the cases can not be used for regular charges.

Since this type load is more frequently used in revolvers it is most often encountered with wheel guns where it locks the cylinder after a couple of shots.

It is not a problem with the cases or the primers.  It is simply a problem presented by physics and gas pressure.

Joel

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Re: Primers pushing out? What would cause this?
« Reply #3 on: October 28, 2013, 07:47:08 AM »
That's interesting, Mortblanc! Thank you.

Many years ago when I competed I made wax bullet loads. According to somebody else's instructions I drilled out the flash holes in the cases I segregated for that use, but the given reason for doing that was different. Maybe if I hadn't done that I'd have noticed the phenomenon - which i confess I don't understand.

Offline 16onRockandRoll

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Re: Primers pushing out? What would cause this?
« Reply #4 on: October 29, 2013, 12:15:58 PM »
I've never run across this, but it makes sense. When the powder charge lights, it pressurizes the primer cup as well as the rest of the cartridge, holding the sides of it in place against the pocket. The primers alone probably made just enough pressure to pop backwards with the small flash holes, but not enough to stretch the cup out against the pocket walls.

Offline res45

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Re: Primers pushing out? What would cause this?
« Reply #5 on: October 31, 2013, 06:30:39 PM »
Unless your firearm has zero Headspace or Head clearance and the primer is flush agents the bolt face all primers back out to some degree.  As mentioned when struck the primer backs out strikes the bolt face or back of the cylinder frame and is pressed back into the primer pocket by the force of the cartridge case moving backwards.

This action can sometime give you a false reading when trying to read primer for pressure levels as the primer are slightly flattened in some instances before being press back into the primer pocket.  Thats why a chrono is a nice tool to have around as well when developing loads.

I haven't had that issues with handgun loads as I don't fire primed only cases,but I have had rifle primers back out slightly and stay when shooting subsonic loads with small charges of pistol powder.  I could remedy that problem by drilling out the flash holes with a 9/64" drill bit but I might want to use them for standard loads at some point and once you drill them out you can't use them for standard loads anymore.  The amount of primer setback I get is not enough to cause any issues.

Here is an illustrated example of how it actually take place.  The illustration is actually for showing how brass stretches and case head separation take place in rifle with excessive head space like the 303 British if the cartridge cases are Fl resized over and over but it serves the purpose of showing primer setback as well.

« Last Edit: October 31, 2013, 06:43:16 PM by res45 »

Offline Secret Squirrel

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Re: Primers pushing out? What would cause this?
« Reply #6 on: December 17, 2013, 01:17:20 PM »
Unless your firearm has zero Headspace or Head clearance and the primer is flush agents the bolt face all primers back out to some degree.  As mentioned when struck the primer backs out strikes the bolt face or back of the cylinder frame and is pressed back into the primer pocket by the force of the cartridge case moving backwards.

This action can sometime give you a false reading when trying to read primer for pressure levels as the primer are slightly flattened in some instances before being press back into the primer pocket.  Thats why a chrono is a nice tool to have around as well when developing loads.

I haven't had that issues with handgun loads as I don't fire primed only cases,but I have had rifle primers back out slightly and stay when shooting subsonic loads with small charges of pistol powder.  I could remedy that problem by drilling out the flash holes with a 9/64" drill bit but I might want to use them for standard loads at some point and once you drill them out you can't use them for standard loads anymore.  The amount of primer setback I get is not enough to cause any issues.

Here is an illustrated example of how it actually take place.  The illustration is actually for showing how brass stretches and case head separation take place in rifle with excessive head space like the 303 British if the cartridge cases are Fl resized over and over but it serves the purpose of showing primer setback as well.



This just seems odd to me unless the primers aren't fitting in snug in the first place. And revolvers don't exactly lock up tight like a bolt gun so these suckers must be bulging or backing WAY the hell out to jam a wheel gun. I'm guessing they (the manufacturer) didn't size the primer pockets correctly.

Res45 On another note I've been reloading for close to 15 years now and have never had to drill out a primer hole but I'm wondering if you do drill them out to like you say 9/64th, why is it that you can't put it back into regular service? Just because of the inconsistency? Seems like a flash holes a flash hole unless you really hog it out like I see some guys do when developing subsonic loads?

Offline Mortblanc

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Re: Primers pushing out? What would cause this?
« Reply #7 on: December 17, 2013, 04:36:20 PM »
If you try to use the drilled out flash holes with regular loads you are going to be dealing with ruptured primers and escaping gas.

This is sort of like gravity.  You do not have to know all the details, it still works and you remain attached to the Earth.

Offline res45

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Re: Primers pushing out? What would cause this?
« Reply #8 on: December 17, 2013, 04:57:23 PM »
Quote
This just seems odd to me unless the primers aren't fitting in snug in the first place. And revolvers don't exactly lock up tight like a bolt gun so these suckers must be bulging or backing WAY the hell out to jam a wheel gun. I'm guessing they (the manufacturer) didn't size the primer pockets correctly.

It doesn't matter how snug your primer fit the primer pocket unless there crimped in place as some military ammo is to keep the primer from backing out or falling out altogether and jamming the weapon they will back out and be reseated by chamber pressure,it's more noticeable if the primers backs out and isn't reseated with underpowered loads like subsonic or plinker loads that are below min. pressure because the load doesn't create enough chamber pressure to stretch and force the case backwards agents the bolt face to reseat the primer. 

Excessive head space can also cause the primer to back out and not be reseated when fired,a case can only stretch so much before the case head separates.  This is very common with 303 British rifles and case head failure from FL resizing the case over an over.  Three way to avoid that,use the O-Ring fire forming method to hold the case head back agents the bolt face and use foreign made brass like Lapua,PPU or Norma that has a thicker rim like the surplus 303 spec brass.  You can do the same with US made 303 brass like Rem. or Win. but the case will stretch more,just make sure you use virgin brass and not somebodies else's once fire brass.  From that point on neck size the case only, You brass will last much longer,not stretch anymore and from that point on the case will head space on the newly formed shoulder.

Primers backing out and reseating themselves really isn't a problem with normal loads in rifles and handguns with standard chamber dimensions with no excessive head space,it's a normal unless the primer pocket itself is worn out. The only way to avoid having the primer back out any at all is to fire form the case and necks size only.  On rimless cases when the rd. is fired the case will stretch to fit the chamber,the case will still head space on the shoulder of the case but at a different point farther forward than the original factory brass dimensions,at this point your primer movement out and back in the pocket will be very little if any.  If your FL resizing the case each time you just repeat the process over and over again. As I stated with standard loads in rifles and handguns with normal chamber dimensions it's not a problem.

Quote
Res45 On another note I've been reloading for close to 15 years now and have never had to drill out a primer hole but I'm wondering if you do drill them out to like you say 9/64th, why is it that you can't put it back into regular service? Just because of the inconsistency? Seems like a flash holes a flash hole unless you really hog it out like I see some guys do when developing subsonic loads?

Ed Harris pointed this out about primer pocket flash holes sizes which may be applicable to  brass made in the US and overseas.

The SAAMI spec. for rifle case flash holes using the large primer is 0.078-0.082.   It is fine to ream them all to the maximum size of 0.082" using a No. 45 drill bit. 

Small primer pocket rifle and pistol cases use a smaller flash hole size of .074"-.078",but some European C.I.P standards boxer primed brass such as Sako and Lapua, IK= Igman or PPU uses 1.6-1.7mm flash holes.

The reason to use and then not not use modified cases for regular loads that have had the primer flash holes drill out to 9/64" or 3.5mm can be found in this article on subsonic loads.  You really don't have to do it in all situations or not at all.  I shoot sub-sonic loads using fast burning pistol powders and cast lead bullets in rifle all the time without drilling out the flash holes,I just use previously fire formed cases and neck size only so the primer don't back out. In the few cases that I have had primer back out and not be reseated to the low pressure loads it wasn't anything that would cause an issue.

 http://members.shaw.ca/cronhelm/DevelopSubsonic.html

Here is another diagram similar to the one in my above post.  This one shows the O-Ring slipped over the case and up agents the rim,it holds the case head up agents the bolt face and when fireformed the case stretches in the shoulder area instead of the web,as I mentioned for this point on the case head spaces on the shoulder instead of the rim. This technique has only been done with 303 British rifles and factory new non spec brass to zero the head space,eliminate brass stretch and extend case life.  In modern rifles with SAAMI spec chambers it not necessary or needed as simple fire forming and neck sizing will accomplish the same thing,


« Last Edit: December 17, 2013, 05:07:58 PM by res45 »

Offline Secret Squirrel

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Re: Primers pushing out? What would cause this?
« Reply #9 on: December 17, 2013, 07:28:31 PM »
It doesn't matter how snug your primer fit the primer pocket unless there crimped in place as some military ammo is to keep the primer from backing out or falling out altogether and jamming the weapon they will back out and be reseated by chamber pressure,it's more noticeable if the primers backs out and isn't reseated with underpowered loads like subsonic or plinker loads that are below min. pressure because the load doesn't create enough chamber pressure to stretch and force the case backwards agents the bolt face to reseat the primer. 

That's odd that I haven't run into this more. I use either CCI 34s, #200's or BR2s and have been fiddling with SS loads but I haven't really messed with the Red Dot or the faster pistol powders. I've been toying with Trail Boss and Puff-Lon. No primers backing out on me though. I actually remembered a long time back a friend asked me to try and make a .40 that would smokestack intentionally in a Glock 22 for his departments training but I wasn't able to do it, they'd either eject or fail to feed (a quasi double feed would have been fine) and go right back in the chamber but I do remember that I had primers backing out on those. I had those things going so slow I swear I could see them go down range. Haha.

Offline TiredOldGrunt

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Re: Primers pushing out? What would cause this?
« Reply #10 on: February 18, 2015, 07:19:36 PM »
This is common and expected when firing empty primed cases.  The primers will back out almost every time. 

Correct, a non issue...  without a full charge, there is noting to seat the base of the cartridge which "keeps the primer flush". in more or less laymen's terms.

TOG

Offline Carl

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Re: Primers pushing out? What would cause this?
« Reply #11 on: February 19, 2015, 03:54:13 AM »
Pressure ,when firing ,is what holds the primer in place,
( think about how easy it is to press a primer in,or out of the pocket)
Low pressure is often mistaken as hi pressure due to this occurring.
It is normal and of no concern .