Primers backing out

[whelen fan]

Hi fellas.

I'm shooting 3006 brass sized with a 35 whelen FL die with a 230gr noe mold and 16.5gr unique. Shoots good but the primers back out after being shot. I'm assuming this is because the shoulder isn't where it should be and I'm wondering what to do about this.

Thoughts?

[dtknowles]

You don't say what you have for a rifle but I assume it is a Bolt Action. Does the action close easily, then maybe you are pushing the shoulder back to far. Back out you sizing die until the bolt won't close on a sized case than then run it in until the bolt will close but with some resistance.

This will get the shoulder in the right place but the primers might still back out a little. The firing pin pushes the case forward a little and if the pressure is low enough the case stays forward but the primer backs up. This happens more with cases with little or no shoulder.

Tim

[JSnover]

What's the history of the rifle? Might not be a bad idea to borrow a go-no gage.

[500MAG]

What load data are you using? Possibly a light load?

[whelen fan]

This is a remington 700 classic. Works perfectly with 35 whelen ammo. And also no problems with real loads in 3006 brass and a 225gr interlock.

The primer problem only happens when I take 3006 brass and use a FL 35 whelen die and then shoot my plinking loads with cast.

[too many things]

don't full length resize, just neck size

[Bodean98]

Try this:
http://castboolits.gunloads.com/showthread.php?152431-Recipes-for-quot-Mouse-Fart-quot-Loads-in-30-06
post #34
Good info by HWNMNBS

[runfiverun]

fire form with a full power jacketed load.

with lighter cast loads you can change your cases head space just by the firing pin driving the case forward in the chamber.
if you get them to the proper dimension to start with it takes longer for this to happen.

[CPL Lou]

fire form with a full power jacketed load.

with lighter cast loads you can change your cases head space just by the firing pin driving the case forward in the chamber.
if you get them to the proper dimension to start with it takes longer for this to happen.

^^^ What he said.

CPL Lou

[M-Tecs]

Try this:
http://castboolits.gunloads.com/showthread.php?152431-Recipes-for-quot-Mouse-Fart-quot-Loads-in-30-06
post #34
Good info by HWNMNBS

I miss the good old days.

[Scharfschuetze]

With very light loads, the pressure in the primer pocket is higher than the pressure in the powder chamber. This is what drives your case forward and shrinks your case between its head and datum point and thus the shrinking headspace and protruding primers.

The solution for your squib or very light load cases is to drill the flash hole out a bit and that helps in reducing pressure in the primer pocket. I keep my modified squib load cases separated and I have shot them more times than I can count without any shrinkage in the base to datum point measurement. Rimmed cases do not need this as the rim is strong enough to resist the case getting pushed forward.

Good case measuring tools such as Mo's and Stoney Point (now Hornady) will help you keep track of such things.

[Wayne Smith]

Guys, it happens in every load and every shot. It is so reliable that John Garand designed his first semi-auto rifle around the principle of the primer backing out of the case! Then the army started crimping primers and he went to the gas design.

What happens is that the primer backs out initially and with normal loads the recoil of the case against the bolt face re-seats it. Light power loads don't have enough recoil impulse to accomplish this.

[whelen fan]

So don't worry about it? As long as I keep my plinking brass separate from my full power loads all should be well I'm guessing. If the should does move back far enough eventually I can chuck the brass or expand the neck past 35, create a false shoulder and start all over again.

[Irascible]

"You don't say what you have for a rifle but I assume it is a Bolt Action. Does the action close easily, then maybe you are pushing the shoulder back to far. Back out you sizing die until the bolt won't close on a sized case than then run it in until the bolt will close but with some resistance.

This will get the shoulder in the right place but the primers might still back out a little. The firing pin pushes the case forward a little and if the pressure is low enough the case stays forward but the primer backs up. This happens more with cases with little or no shoulder."
Tim

What he says. You have a modern gun, not one designed to fire dirty, muddy ammo in the middle of a battle.

[Scharfschuetze]

Guys, it happens in every load and every shot. It is so reliable that John Garand designed his first semi-auto rifle around the principle of the primer backing out of the case! Then the army started crimping primers and he went to the gas design.

Not true. If a rifle is headspaced properly and ammo is loaded to its proper dimmensions, then the primer cannot back out. Headspace gauges and case measuring tools will confirm this. You can run a repeatable series of tests to prove case shrinkage with squib loads by segregating 10 cases of standard flash holes and 10 cases with drilled flash holes and then loading squib loads in both and then keeping track of the shrinkage with a good case measuring tool between your two groups of cases.

John Garand's initial designs for his rifle did indeed use a primer actuated mechanism. While clever, it was really a dead end in the end and I know of no military or sporting rifles that ever went into large scale production using this form of operation. The combined gas pressure in primer pocket and the case pushed the primer back against a button on the bolt face thus initiating the cycle of the rifle. What is important to note here is that the rifle was designed to allow the primer to set back. It was not the result of "it always happening" as a solid bolt face will not allow this when all is to spec between headspace and case dimensions. Garand's experimental model of 1923 was the last of a series of his designs that used the primer set back system as he moved on to a gas cup design rifle and then finally to the gas piston design that we are all familiar with.

The military had something like 2 billion cal 30 rounds with crimped in primers in storage at about this time frame and the primer set back designs required a non crimped round to function. Budgets of the 20s probably killed off any idea of obsoleting so much ammo with a new design. This is the reason that General of the Army MacArthur used to kill off the .276 Pederson round that John Garand preferred for his later rifle designs.

Military ammo has generally enjoyed crimped in primers since WWI when the advent of full auto machine guns mandated the extra step in production.

I load for the 35 Whelen and use the 200 grain RCBS design boolit. With velocities in the neighborhood of 1,700 fps and higher I've not noted any primer set back or case shrinkage using cases with un-modified flash holes. When loading 158 grain cast boolits designed for revolvers at lower velocities over Unique powder, I use the drilled out flash hole cases (see my original post) and I have not suffered any shrinkage of cases or protruding primers.

My 35 Whelen based on a Military Mauser 98 action.

[HangFireW8]

Try this:
http://castboolits.gunloads.com/showthread.php?152431-Recipes-for-quot-Mouse-Fart-quot-Loads-in-30-06
post #34
Good info by HWNMNBS

Too bad he didn't list his rifle. I wonder if the massive 1903 firing pin would have different results than, say, a 700.

[dtknowles]

Too bad he didn't list his rifle. I wonder if the massive 1903 firing pin would have different results than, say, a 700.

In his second post he said it was a 700.

[Shuz]

FWIW--Yesterday I was shooting my Remington 700 CDL in .35 Whelen with a Noe 360-318HP boolit, sized to .359. Both 16 and 17g of Unique for powder charges. Primers were CCI 200. Some of the brass used was .30-06 necked up and others were original .35 Whelen brass. The 16g charge chrono'd an average of 1550fps with an Sd of 16. Accuracy was only so so with the occasional flyer that really opened up the group to 4" @100 yds. The 17g charge chrono'd 1571 fps with an Sd of 9. The accuracy was much better, approx 2"@100yds. Interestingly, the 17g charges were driving cup pointed boolits at 245g, whereas the 16g charges were driving standard hollow points that weighed 235g.
The point I really wanted to make.....was that at no time did my primers back out on either load.

[Don Fischer]

Backed out primer's accompanied by the case being blackened down onto the shoulder and below say's to me, not enough pressure. What happen's is the case doesn't expand enough to seal the chamber and the primer back's up a bit but not enough pressure to drive the case back and re-seat the primer. Try using more pressure!

[gnostic]

If the loads too light, the primers will back out. What's the rest of the case look like, smoked up maybe?

[MtGun44]

Happens with light loads. Primer pops out under pressure like a piston,
pushing case hard forward, in some instances even setting the shoulder
back slightly. Then the pressure isn't enough to drive the case head back
against the bolt, the only thing holding is friction of the front 80% or so of
the case against the chamber wall.

No real harm, but may eventually shorten the brass a good bit.

Primers pop out on all loads, but full pressure loads stretch the case out and
reseat them as the case head is pushed to hit the bolt face.

Bill

[Shiloh]

What's the history of the rifle? Might not be a bad idea to borrow a go-no gage.

+1

Particularly on well used military relics.

SHiloh

[whelen fan]

Took some pictures.

Backed out primers, fired brass, 17gr unique with 230 cast and group at 100 yards.

http://img.photobucket.com/albums/v134/Kman338/Mobile%20Uploads/20160701_082947-1_zpsfb1y7ak0.jpg

http://img.photobucket.com/albums/v134/Kman338/Mobile%20Uploads/20160701_082937-1_zpsihier2xc.jpg

http://img.photobucket.com/albums/v134/Kman338/Mobile%20Uploads/20160701_082914_zps7zi1okgt.jpg

http://img.photobucket.com/albums/v134/Kman338/Mobile%20Uploads/20160701_082848-1_zpsjmm7a6xz.jpg

[44man]

All has been said, no comment from me. they key was loads too light.

[Ballistics in Scotland]

You didn't say how far they were backing out, which could be important. It happens to the extent of the headspace excess of chamber (to the shoulder) over the same measurement in the cartridge. If it was excessive it could be caused by an over-deep chamber (perhaps a little dangerous when you switch to full power) or stretching or cracking of the action (worrying at any time.)

Now, however, those pictures look like the headspace is within safe limits.

I think this is primarily an effect of gas pressure, rather than primer pressure within its pocket. Try popping a primed but unloaded case and you might find the primer set back, but more often you won't. It doesn't matter very much though, as the things that happen happen a tiny fraction of a second later.

It happens because the adhesion of case to chamber, caused by the gas pressure, is too great to be overcome by the light pressure of this round. It actually indicates a very safe condition. With hot loads in the same rifle, a few things would happen which aren't very dangerous when it is on this scale, but might limit brass life. The head is forced back against the bolt face, stretching the brass. With a very tapered case that stretching occurs in the last fraction of an inch, but with the very straight-bodied Improved types stretch most of the way back to the shoulder.

I never did believe that cartridges like the .300H&H and .303 necessarily produce less accuracy or shorter brass life, and people used to get extremely high standards in both from rounds like the .30-40. But they need more accurate headspacing to do it.

Another effect of the primer being extruded and subsequently the case stretched backwards, is that it tends to mushroom the primers, leaving them with sharper edges around the edge of their pockets. That can falsify a sign of higher pressure than you in fact have. But it would produce an error in the direction of safety.

[WALLNUTT]

My primers back out in my 30 06 with light cast. It always fires, shoots good,what's to be concerned with? I neck size them and shoot them again.

[whelen fan]

All has been said, no comment from me. they key was loads too light.

If the loads are too light, how much unique can you safely use to make this not happen?

[whelen fan]

You didn't say how far they were backing out, which could be important. It happens to the extent of the headspace excess of chamber (to the shoulder) over the same measurement in the cartridge. If it was excessive it could be caused by an over-deep chamber (perhaps a little dangerous when you switch to full power) or stretching or cracking of the action (worrying at any time.)

Now, however, those pictures look like the headspace is within safe limits.

I think this is primarily an effect of gas pressure, rather than primer pressure within its pocket. Try popping a primed but unloaded case and you might find the primer set back, but more often you won't. It doesn't matter very much though, as the things that happen happen a tiny fraction of a second later.

It happens because the adhesion of case to chamber, caused by the gas pressure, is too great to be overcome by the light pressure of this round. It actually indicates a very safe condition. With hot loads in the same rifle, a few things would happen which aren't very dangerous when it is on this scale, but might limit brass life. The head is forced back against the bolt face, stretching the brass. With a very tapered case that stretching occurs in the last fraction of an inch, but with the very straight-bodied Improved types stretch most of the way back to the shoulder.

I never did believe that cartridges like the .300H&H and .303 necessarily produce less accuracy or shorter brass life, and people used to get extremely high standards in both from rounds like the .30-40. But they need more accurate headspacing to do it.

Another effect of the primer being extruded and subsequently the case stretched backwards, is that it tends to mushroom the primers, leaving them with sharper edges around the edge of their pockets. That can falsify a sign of higher pressure than you in fact have. But it would produce an error in the direction of safety.

My primers do not back out with full power jacketed loads and on cases that have 5 firings there is no indication of incipient case head separation when checking with a bent paper clip.

[44man]

If the loads are too light, how much unique can you safely use to make this not happen?
Don't know. Why Unique when you have slower powders? Big case suited to much better choices.

[whelen fan]

Well I have about 30 lbs of unique in a steel drum from the 50s and the whole reason for me having the whelen is because I can get brass for free and shoot it dirt cheap.

[Ballistics in Scotland]

My primers do not back out with full power jacketed loads and on cases that have 5 firings there is no indication of incipient case head separation when checking with a bent paper clip.

You have just answered your own inquiry in your previous post. With those Unique loads you don't have to stop it happening.

[casac47]

I agree with Don Fischer. Under normal pressures, the casing expands to fill the chamber. Once the shoulder can't move, the rest of the brass swells backward until it slams up against the bolt head. If the primer was backing out, this action will re-seat it in a hurry. You would never notice it unless there is leakage around the primer.

[Yodogsandman]

How about using that Unique load and seating the boolit out far enough to jam in the rifling and push the case back against the bolt face hard. So that the bolt closes with some resistance. This will increase initial pressures, sealing the chamber with the case better and preventing that case from moving as much when the primer is fired.

[TXGunNut]

Looks to me like some good plinking rounds. Good pics of the case; sooty neck, backed out primer, no bright ring at the web. If you had headspace issues you'd probably be seeing a bright ring just above the web after 2-3 firings, if not after the first. If it makes you feel better get some chamber gauges, like most precision tools they aren't cheap.

[murf205]

Well I have about 30 lbs of unique in a steel drum from the 50s and the whole reason for me having the whelen is because I can get brass for free and shoot it dirt cheap.

That's about as good a reason as one could have. I guess it's safe to say that the powder shortages of Unique didn't even make a blip on your radar. Ever wondered how many primers it will take to shoot up 50 lbs of Unique? You are very fortunate.

[44man]

How about using that Unique load and seating the boolit out far enough to jam in the rifling and push the case back against the bolt face hard. So that the bolt closes with some resistance. This will increase initial pressures, sealing the chamber with the case better and preventing that case from moving as much when the primer is fired.
This is the solution. Or neck size for resistance with the bolt. FL is too much.

[Ballistics in Scotland]

That is a solution. Now what is the problem?

[44man]

It is something I never figured out. Brass grips the chamber but does it stretch back to seat a primer again? or does pressure drop so the brass can move back with barrel pressure? Unique will peak fast and lose the barrel pressure so brass has no more drive. Powders that burn in more length to extend peak down the bore will add push. Brass retracts from the walls as pressure drops.
Some military guns that use blow back have fluted chambers to hold brass longer to prevent gun damage.
Unique is just not efficient in the large case so it peaks instantly to punch the boolit and then does no more.
I would look at 3031, 4895 or even Varget and why not 4350?

[Ballistics in Scotland]

It is something I never figured out. Brass grips the chamber but does it stretch back to seat a primer again? or does pressure drop so the brass can move back with barrel pressure? Unique will peak fast and lose the barrel pressure so brass has no more drive. Powders that burn in more length to extend peak down the bore will add push. Brass retracts from the walls as pressure drops.
Some military guns that use blow back have fluted chambers to hold brass longer to prevent gun damage.
Unique is just not efficient in the large case so it peaks instantly to punch the boolit and then does no more.
I would look at 3031, 4895 or even Varget and why not 4350?

Fluted chambers do just the opposite, by reducing friction to permit movement of the case. In many rifles, such as the CETME, headspace works normally and the fluting simply facilitates extraction. But in the Oerlikon 20mm. cannon the chamber actually admitted the bolt and extractor, permitting ignition of the primer before the bolt had come to a standstill. The first impulse of the gas pressure thus came while it had to overcome the inertia of a forward-moving bolt, rather like kicking a door moving towards you will hurt your toe much more than a stationary one.


I wouldn't draw conclusions from what happens to the primer in the Oerlikon, as it was quite exceptionally crimped in. But it originally required greased cases, to permit the long movement of the case in the chamber, and this was later replaced by a fluted chamber.

A fired case with extruded primer indicates that with that load, the case didn't move backwards at all. As to what happens with a high pressure load, there is no reason why it should be the same every time, but I think it is normally the case stretching rearward. If it was otherwise, the location of head separations wouldn't be as precise as we see it to be.

A primer fired in the gun without powder produces far less pressure than a conventional or perhaps even very light load would do. It is also, being a tiny quantity of high explosive, much more momentary. But it is still not low. If you ignite a primer on a hotplate (cover it, because you don't know which way it will go), the explosion is enough to blow out one side of the cup. It is hard to see how the primer could slide rearward with that pressure locking it in its pocket.

I think primer movement comes later, with the more protracted pressure of the powder gases, and probably the early part, while the primer pressure has vanished and powder pressure is low. The Unique load is enough to produce adhesion of the brass, but a higher pressure load would stretch the case back in line with the rear of the primer. The highest would produce swelling of the unsupported part of the primer, and the moving brass would size the primer down, except for the sign we usually find disquieting, the edge of the primer swollen into the chamfered edge of the pocket.

[44man]

High pressure does stretch the brass, good reason not to set shoulders back, just the very light loads like shown that is hard to figure. Not enough pressure to push or stretch but brass will last longer.
There were a few semis and autos made to start the bolt movement with the primer impact until the crimped in primers came out.
The ruined cases I used to find on the range from an auto, don't remember the make but might have been Israely. I read about it and it said the flutes retarded bolt movement until pressure dropped off.
I shoot heavy 296 loads from my .44 with heavy boolits and primers get pretty flat since they move out and the case comes back to re-seat them. Brass never grows so the case is moving. Pressure drop is faster in a revolver because of the gap, so much so carbon gets on the brass and even lube is blown back. There is enough internal pressure on the primer to push the hammer to near full cock. Primer set back can be used to cycle an action but is not reliable.
Some old Colt SAA's had sharp pins that punctured primers and the gun would run full auto.
Hammer bounce and a cylinder lock that jumped out of the slot from inertia is what caused some X frames to double. It was NOT the hammer going back far enough to unlock and rotate the cylinder because the cylinder turned backwards. To prevent doubling, leave the chamber under the hammer empty or put a strong lock spring in. There is a lot of pressure from the flash hole so it does push the primer out.
Have you ever shot a cheap repro Italian ML with a large nipple hole? It will cock the hammer against a very strong spring and blow the cap into shrapnel. I use only CCI or REM caps even with a good nipple, RWS and some Italian caps will be brittle and stick pieces in your chin or nose. Safety glasses are a MUST.

[44man]

The cases shown by the OP is like shooting rubber boolits with a primer only. Primers back out so the cylinder won't turn. Had to drill the flash holes larger but the brass is no good for other loads.

[Motor]

I admit I didn't read all of the replies but what you have is common.

Yes your casing headspace is shorter than it needs to and this is what's happening:

Your firing pin strike is pushing the casing up against the shoulder. The pressure expands the case and holds it to the chamber wall. The primer backs out to the bolt face.

This same thing occurs with full power loads but with full power loads the pressure typically rises above what the force holding the case to the chamber wall.

I like to "short size" my brass for bolt action cast loads. This typically sizes the case body some and the neck but leaves the shoulder alone. Eventually the shoulder will expand forward and you'll quit getting backed out primers.

Or as posted above you can simply size to fit your chamber better but it may take a few firings to even expand your brass to where you'll get an accurate reading. Or you can use a casing from a full power jacketed load.

Motor