Headspace

[fixit]

Today, I shot my new to me Springfield 840 for the first time. It shot well, but I discovered that it's got a headspace issue. Primary indicator was the primers were unseated in firing. This means I will have to have two sets of brass, each fire formed in their respective chambers. Fun!

[richhodg66]

I assume it's a .30-30? Headspaces on the rim. Might be something else.

[Uncle Grinch]

Are you shooting handloads... maybe low power loads? These will cause the primer to back out some. If so try upping your load or going to a quicker burning powder.

[Petrol & Powder]

What cartridge is the rifle chambered for?

[richhodg66]

If I recall right, a Springfield 840 is a Savage 340. Almost certainly a .30-30 if that's the case.

[fixit]

sorry about that. yes, it's a 30-30. as for the rounds, lower powered hand loads did not raise the primer, full power factory ammo did.

[Petrol & Powder]

When you say "raise the primer", do you mean the primer backed out of the primer pocket or the primer flattened ?
A flattened primer indicates excessive pressure.

You can do a quick & dirty check of the headspace by placing some tape on the base of a sized casing and closing the bolt on that empty casing. Successive layers of tape will give you an idea of excessive headspace, if it exists.
Remember that rimmed cartridges headspace on the rim, not the shoulder.

[Larry Gibson]

sorry about that. yes, it's a 30-30. as for the rounds, lower powered hand loads did not raise the primer, full power factory ammo did.

Not really a "headspace" problem as many, if not most, 30-30s will do the same thing. A "full power factory" load generates enough psi for the case to obturate and seal the chamber but not enough psi to overcome the case grip on the chamber walls or to cause the case to stretch in the web area and be pushed against the bolt face keeping the primer flush in the primer pocket. Your "lower powered loads" do not have enough psi to cause the case to grip the chamber walls, if the case obturates at all, and the case is driven back against the bolt face. Neither is a real cause for concern with the 30-30.

Your rifle is an excellent candidate for using fire formed NS'd cases. To fire form my 30-30 cases I use 25 gr H4895 (no wad or filler) and a 311041 or 311291 seated long so the drive band is forced into the leade when chambered. I single load these and they make a pleasant plinking load so it's fun shooting when fire forming. I then NS the cases for further loading and the cases last practically for ever.

[Petrol & Powder]

+1 on neck sizing cases for a particular rifle. Your brass will last longer and often your groups will get smaller.

[txbirdman]

What Larry said. I’ve been doing the same with my 1948 model ‘94 Winchester for years.

[Gtek]

Those little red and blue plastic boxes with white labels on the end having a model and S/N has sure made my experience sweeter. Cheaper NO, more enjoyable, YES!!!

[fixit]

The primer backs out of the case, .005 to .010, to my machinists eyes. Larry, your explanation of the behavior of mediums pressure rounds fits this scenario. Petrol, I did the tape trick earlier, and I would say my headspace is in, but not far from excessive. There was slight resistance from tape compression, but the bolt did drop with the tape on the round. That said, neck sized, rifle specific ammo is never a mistake!

[popper]

Don't rimmed cases in a bolt rifle HS off the bolt lugs? Possible solve the problem by setting the neck farther forward or just neck sizing fired cases.

[GBertolet]

I neck size for my 30-30 788 Remington. Get a Lee collet neck sizer. With cast bullet pressures, you can go a very long time before FL sizing is necessiary. When you have trouble closing the bolt, it's time to FL. Your headspace should be about zero then. Then only FL size enough to allow the bolt to close with a little feel. Then you are good for a while again. In reality, you are adjusting to headspace simultaneously, on both the rim and shoulder. This is good. Primers should not back out then.

[fixit]

well... i finally got to shoot this rifle for accuracy, and, to put it lightly, i am thrilled! with the recoil pad i put on to lengthen the stock, it shoots soft, and then the pillar bedding and free floated barrel, it is doing everything i had hoped for. based on the range time, i wouldn't hesitate to shoot 150 yards for deer, even more, possibly, if i could spend some time on a longer range set up. factory ammo, with a proper rest and taking my time, will go into one ragged hole at 25 yard indoor the range i was, 50 yards is available where i hunt, and i'll be testing that out, too.

[Three44s]

So ..... did neck sizing or partial full length sizing cure the primer back out problem?

Three44s

[fixit]

That is still a work in progress. The accuracy report was just me being thrilled that it shoots as like it does!

[richhodg66]

Those 340s are better rifles than they have any right to be. I'm a fan.

[fixit]

After finally getting to punch paper for groups, I would say I'm a fan, too. I was suprised at the number of detractors I saw on the internet, which is why I went to the lengths I did in prepping this rifle.

[firebyprolong]

Nice thing about the savage 340 design is that excessive headspace is easily cured. Pop that barrel nut free and screw the barrel in on a go gauge. Only hang up is getting sights to clock correctly. Numeric even has brand new 840 marked and blank 30-30 barrels the last time I checked. I like 340s and 830 too, the several that one owned and sold off or gave to young shooters were more accurate than a budget rifle had a right to be.