Rebounding primers.

[bootsnthejeep]

Finally got to put some boolits thru my WECSOG Scout rifle (based on a previously bubbafied 03A3 Springfield), and was pleased with the initial results until I started collecting my brass.

They were light loads, 16-18 grains of 2400 under a 311291, and in all my spent cases the primer had backed out maybe a 32nd of an inch. Visually apparent, and felt just like a primer that hadn't seated all the way, but they were all fully seated when they were loaded.

Also, about half of the cases showed a bright ring on the base, right down the middle of all the letters on the headstamp, between the primer pocket and rim of the case.

Headspace issues? This is a new milsurp bolt that was (allegedly) headspaced in this receiver, but I didn't see it with my own eyes.

I've not run onto this before. Thoughts?

[Lizard333]

If i had to guess, and this is only based on my limited experiance, I would have to say that it was because your load was too lite. I believe someone explained this somewhere else so I am going on my memory. When a round is fired it will always push the primer out due to the pressure of the round going off. It only gets pushed back in when the recoil pushed the brass back into the bolt, casuing it to re-seat. You get different degrees of "re-seating" because you will get a flatter primer with a heavier load. I am sure someone else with more knowledge will chime in.

[303Guy]

That sounds like a rather excessive amount! I wouldn't think there'd be any harm is shooting those loads in the gun but I would be careful with higher loads. A fire-formed case would be no problem but to fire-form the cases they would need to be lubed so they don't stretch at the web/body zone. Such fire-forming loads should be warm enough to push the shoulder forward but mild enough not to stress the action. I'd think a slower powder with longer pressure rise time and lower peak would be the best way. Best would be to get the gun checked and corrected.

[AggieEE]

I would have to agree with Lizard333. I've read somewhere, I think one of the reloading manuals, that the firing pin drives the case forward the primer backs out then as a full pressure builds it pushes the case back to the bolt face and reseats the primer. Try 1 factory round and see what the primer looks like I would bet normal but by all means have the headspace checked first cheap insurance.

I've fire formed some cases for my tight neck 220 Swift by seating the bullet long so I had a jam fit then a starting load for the j bullet maybe a little more worked fine.

AggieEE

[excess650]

It sounds like excessive headspace combined with a low pressure round. In this scenario the primer will back out of its pocket enough to fill the gap to the bolt, but there isn't enough pressure inside the case to cause the case shoulder to push forward. A high pressure round will cause the case to stretch and reseat the primer.

Even if you have 'too much headspace" for factory spec ammo, you can reset your sizing die so that it doesn't touch the shoulder. If this is your only rifle in this caliber I would just expand the necks up to 8mm or 35cal and then resize the cases in the full length sizing die backed away from the shellholder about 1/16". Continue adjusting the sizing die towards the shell holder until the bolt will just close. Now you have zero or near zero headspace.

Repeated firing of low pressure rounds can cause the shoulder to be set back. The primer forces the case forward and slams the shoulder into the chamber while the primer remains backed out of its pocket.

[Lizard333]

I would have to agree with Lizard333. I've read somewhere, I think one of the reloading manuals, that the firing pin drives the case forward the primer backs out then as a full pressure builds it pushes the case back to the bolt face and reseats the primer. Try 1 factory round and see what the primer looks like I would bet normal but by all means have the headspace checked first cheap insurance.

I've fire formed some cases for my tight neck 220 Swift by seating the bullet long so I had a jam fit then a starting load for the j bullet maybe a little more worked fine.

AggieEE

Better said than I, but you get the point. As long as you have never had any problems in the past with factory ammo or regular, I wouldn't worry to much about your headspace.

[JRR]

I have three Mausers. A 24/47, a BRNO and a Turk with large ring and small threads. All three had the primer set back issue using Remington factory loads. After full length resizing in RCBS dies and loading 200 gr. cast boolits with anywhere between 14 gr. of Unique to 20 gr. of 2400, the problem has disappeared. I attributed this to an under-pressure load. In your case with the 30/06, (I presume) I would not expect under pressure from factory ammo. Get the head space checked.

Jeff

[Wayne Smith]

This phenomona is so reliable that John Garand designed his first semiauto rifle to function on this basis. I don't specifically remember but I think that changed because the Army went with crimped primers. What you experienced is common with light loads, and those who routinely load light loads will select cases and drill out the primer flash hole larger and reserve those cases for the light loads. This reduces the back pressure and reduces the primer movement.

[mroliver77]

I agree about light loads. 16-18gr 2400 is not that light of a load!
If you have any fresh 06 ammo you could remove the extractor and find something to stick to the case head thereby making a hillbilly headspace gauge.Start with something .002 or so and add until you feel it take up all the room. A real gauge is best but this will give you some idea.

Check the bolt face for a burr or high spot that is causing the bright line. You know if there is a high spot it could cause both anomalies.
J

[geargnasher]

+1 on the Hillbilly Headspace gauge, I've found some guns that would accept a disc of raisin bran box between the bolt face and the case head. My solution for at least one gun, after verifying the action is ok but headspace a little long, is to use fireformed cases and don't set the shoulder back when you resize. Seating the boolits to engrave hard tends to help hold the case head against the bolt when firing.

Gear

[BAGTIC]

It is why cases made for blank cartridges have oversized flash holes to vent the primer gas into the case so it won't back out the primer and lock up the gun.

[BAGTIC]

Fire forming cases works better with a fast powder such as Red Dot, etc. One wants a fast pressure rise to expand the case without creating enough sustained pressure to stretch the web. 10 grains of Red Dot and a quarter sheet of toilet paper is recommended for 'standard size' rifle cartridges by Ken Howell in 'Designing and Forming Custom Cartridges For Rifles and Handguns'. GREAT BOOK!!

[cbrick]

The original Mr Speer did a series of tests on backed out primers about 40 or so years ago. He wrote an article on it that I think was in one of the early Speer manuals. He determined that a light load would create enough pressure to seal the case against the chamber walls and hold it without allowing the case head to reach the breech, the pressure inside the case would push the primer out. Improper headspace would make the problem worse but this can still happen if headspace is correct. Higher pressure loads can do the same thing except the case stretches and slams the case head against the breech re-seating the primer, a cause of really flattened primers in other wise normal pressure loads. A reason to not use primer appearance as a judge of pressure. Assuming headspace is correct fireformed brass should cure the problem as long as you don't push the shoulder back when sizing.

Rick

[303Guy]

... slams the case head against the breech re-seating the primer, a cause of really flattened primers in other wise normal pressure loads. A reason to not use primer appearance as a judge of pressure.Yup. I was horrified to see flattened primers on what I thought was a middle of the road load - until I remembered those were new cases! Another reason not to rely on primer pressure indications is fast burning pistol powders. They can over pressure the case without flattening the primer! (A rifle case, that is).

[bootsnthejeep]

Ok, so what I'm hearing is take all existing this-rifle-fired brass, neck size only, and try it again and see what happens.

18 rounds of this brass was Rem factory ammo (200 grain jacketed slugs or something. Ouch), and I pretty confident the bases were normal with seated primers, I think I would have noticed.

Ok, sounds good. I wasn't terrified of it, I just thought it was odd.

[prs]

Fire forming cases works better with a fast powder such as Red Dot, etc. One wants a fast pressure rise to expand the case without creating enough sustained pressure to stretch the web. 10 grains of Red Dot and a quarter sheet of toilet paper is recommended for 'standard size' rifle cartridges by Ken Howell in 'Designing and Forming Custom Cartridges For Rifles and Handguns'. GREAT BOOK!!

Can you explain what is done with the TP? Is it used as a wad instead of using a boolit? Or, if the gun bursts the chamber; I'm gonna need more TP than that!:mrgreen:

prs

[Larry Gibson]

Bootsnthejeep

Did you FL size the cases?

This is a normal occurance many times with such loads. Best to use well fire formed cases and NS.

Larry Gibson

[Char-Gar]

1. I know about the theory of primers reseating and all of that. I have two 03A3 rifles and fire 16 to 18 grains of 2400 in them over a good cast bullet and do not get any primers backing out.

2. I also know about cases developing headspace over time with light loads due to being shoved forward into the chamber and not enough pressure to blow the shoulder back out.

3. I also have drilled out flash holes to prevent No. 2 above.

After thousands of rounds of cast bullets over 2400 in 03A3s this is what I have learned.

A. 16 t0 18 grains of 2400 generates enough pressure to keep primers from backing out and cases being shortened in headspace over time.

B. Cases with driled out primer flash holes do no harm and do not have any effect on accuracy, but at the load level above are not needed. You must be very careful and not load these cases will full snort loads.

To give a direct answer to the original post, Fire some full snort jacketed loads in your rifle and that will fire form the cases to your chamber. Then neck size only and load with cast bullet as you have been doing. That will stop the primers from backing out with your loads even if you have a slight headspace issue. At your current pressure level, there should never be a need to full length resize those cases.

If you uses loads with even less pressure and the primers start to back out again, this will tell you the cases are shortening and developing headspace. Then it is time to think about drilling out flash holes.

In short you don't have a significant problem and one that can be solved quite easily and should not be a cause of worry.

As always...read my disclaimer below.

[Char-Gar]

Can you explain what is done with the TP? Is it used as a wad instead of using a boolit? Or, if the gun bursts the chamber; I'm gonna need more TP than that!:mrgreen:

prs

What BAGTIC left out is you don't put a bullet in those loads!!!!! The TP wad is all their is and just serves to hold the powder charge in place.

This methods works good enough to form cases in a wildcat cartridge or making one case from another. It will get you to the point a bullet can be loaded and the round fired in the chamber.

If you are dealing with trying to custom fit a standard case to a standard chamber, I much prefer to fire a full snort jacketed bullet load. This will give you a custom fitted case to your chamber with no issues.

[bootsnthejeep]

Larry, I did FL size all of them, despite the fact that I'd fired them all in this gun with full snort loads. I managed to buy the Lee die kit that had everything EXCEPT the collet neck sizing die. For some reason, all the different Lee kit combinations confuse the hell out of me. I knew which one I wanted and STILL managed to grab the wrong one at Cabelas. Anyway.

Progress. Eventually, progress.

[geargnasher]

Just a note, firing "full snort" loads where the boolit isn't seated out far enough to contact the rifling such that you feel light resistance of the bolt handle as you cam it home can and will cause stretching of the case forward of the head. Such is the case with most j-word loads and factory loads where the boolit "jumps" to the rifling. If the case head isn't firmly against the bolt face after the firing pin strike, the case will stretch rather than push the shoulder forward like we want.

The firing pin will push a case into the chamber until the rim bottoms out or the shoulder does (or belt, or case mouth, or whatever determines headspace) unless there is a boolit for it to stop against.

Once fireforming is complete, neck size and this shouldn't be a problem. The .30-30 will now headspace on the front shoulder and case body taper rather than the rim, and the case won't be stretched.

Gear

[303Guy]

... can and will cause stretching of the case forward of the head. Indeed! I use moderate loads and keep my cases lubed - as stated before - not dripping with oil! The slight lubing allows the pressurised case to progressively creep back against the bolt face without stretching it at the web and spreading the elongation over the length of the case body. It still grips the chamber. This method does push the shoulder forward - or rather, pushes the rest of the case back while the shoulder remains firmly up against the chamber. This effect can be seen by firing a polished case. The slide marks left on the case can be seen to be a little longer toward the rear than at the front end where the marks can be very short.

[Mk42gunner]

Fireformed brass and neck sizing will work for your cast loads; but headspace guages for the .30-06 aren't that expensive, you can even rent them for very little money.

Myself, I would rather be sure that a rifle is properly headspaced; especially if I am reading your post correctly in that you are using a different bolt.

Robert

[BAGTIC]

Can you explain what is done with the TP? Is it used as a wad instead of using a boolit? Or, if the gun bursts the chamber; I'm gonna need more TP than that!:mrgreen:

prs

He said to use it as a wad.

I don't know if the book is still 'In Print'. See if your public library can borrow a copy of Howell's book through interlibrary loan. Most libraries the service is free though a little slow. The book is great.

[BAGTIC]

The traditional way of of measuring presures in Europe was by using lubed cases and a crusher gauge in the face of the breech that measured bolt thrust. That was one reason for some of the discrepancies between reported US and European pressures. Same pressure but different way of measuring it. Much like difference between CUP pressures and PSI pressures. I believe the Europeans were considering a change to the American PSI system

[MtGun44]

cbrick nailed it. I've seen this with light load in several rifles. Nothing to sweat.

Bill