15 thou. headspace on M1917... what to do?

[Patrick Chadwick]

In 3 firings, cases have stretched beyond max length.

Sounds like you really have got a rifle with a larger than specified headspace.
But if you were a reloader for original blackpowder cartridge rifles, you would be used to the idea that every rifle has to be treated as an individual. Especially if you want to get the best performance out of it.

But a case that becomes so long that it jams up at the mouth is bad, because this causes extra pressure by hindering the expansion of the mouth and the release of the bullet. - If you force in a slightly overlong case, the mouth will be crimped! So I would trim the cases to the standard length. Once you necksize they will grow very little. I have lost count of the number of times I have reloaded my match set of Geco cases (cases from the same lot, weight matched to within 1 grain), but it could well be into double figures, and only now are some reaching the maximum length. Good cases will last so long with necksizing that there is little point in keeping count. Just retire the whole set if any splits occur (I have never had one with my 30-06 cases).

[jmoore]

In 3 firings, cases have stretched beyond max length.

That's not normal.

Are you lubing the insides of the necks to ease expander ball pull out?

[Chuckindenver]

try another bolt and see if that cures the issue.
also, some early winchesters are know to have over sized chambers..
common issue with 17,s and 14,s is bolt set back, gualing of the locking weighs..not repairable.

[CouldBeWorse]

I bought a couple of 1917 bolts, so I'll see how they do when they get here.

I also shot some Winchester factory ammo yesterday, deprimed, cleaned, neck-sized and measured case length:

2.492, 2.493, 2.493,
2.495, 2.496, 2.496, 2.497, 2.500, 2.501

6 of 9 were longer than the 2.494 max case length, after a single firing. I'm not sure how unusual that is.

I neck-sized and trimmed all my cases back to 2.487, but I suspect that 2/3 of them will be longer than 2.494 after the next firing.

I think that what I need is a neck sizing die that produces a cartridge which is 10 thousandths longer than a "normal" cartridge between heel and shoulder. Then it wouldn't need to stretch. Is that adjustable on a press? (I have the Lee Classic Loader).

[MOS-45B]

Couldbeworse,
Have you seen or heard of the "RCBS Precision Mic". About $50.00 from MidwayUSA. It is a great tool to have on your bench when reloading for excess headspace. It is used to accurately determine the amount of headspace in a chamber by measuring the fired cases. The tool measures from the base of the case to the datum point on the shoulder. With the aid of the tool, you can use your full length resize die to "set-the-shoulder-back" .001, or .002 thousands when you resize. This produces cases that are custom fit for one chamber.
I have a 1917 with excess headspace. The bolt will close on a field gauge. Fired cases measured in the RCBS Mic were shown to be .006 to .007 over the ANSI minimum value of 2.0487, and still within the acceptable range for 30-06 headspace. Have had no problems firing or reloading for this rifle. It is always best to consult a professional gun mechanic on these matters.

[Patrick Chadwick]

With the aid of the tool, you can use your full length resize die to "set-the-shoulder-back" .001, or .002 thousands when you resize. This produces cases that are custom fit for one chamber.

An excellent tool, if you have one. But I fire several calibers for which I would not be able to acquire headspace gauges, let alone an RCBS Precision Micrometer.
All my cases are fired fully sized once, and thereafter ONLY resized on the neck, so that the bullet is properly gripped. The shoulder is not set back at all.

The thinking behind this is quite basic. Brass can be handled to be anywhere from dead soft to fragilely brittle. Cartridge cases are made so that the base end is fairly hard, but the neck is noticeably softer. However, it is still elastic. On firing, the case expands to fit the chamber. Inevitably, the base will be pushed back hard on the bolt face. And the shoulder will be pushed forwards hard on the shoulder slope in the chamber. This will happen even in a 308 case fired in a 30-06 chamber.

So why doesn’t the fired case jam in the chamber?

Because the brass has some elasticity, and thus springs back to a size that is a mite smaller in all dimensions than the chamber. If it did not do so, the case would have to be driven out of the chamber by ramming a heavy rod down the barrel. And if the chamber has a widened region or a slight ring - caused, for instance by Bubba removing rust with a steel wire brush or abrasive paper on an electric drill - then that is exactly what will happen.

Please note – if cases jam in the chamber, you should check the chamber itself!

If your cases extract properly after firing, then you have no such problem and we can continue!

The once-fired cases are an exact match to that rifle. It would be ideal if you could use the same cases again, without any resizing at all. And that it indeed what bench-rest shooters strive for. Alas, this is not usually the situation for service rifles, as the chambers are typically so generously dimensioned that a bullet that would fit snugly in a fired case would be too large for the barrel. So we must tighten up the neck section before being able to reuse the case. But if those cases are ONLY going to be reused on the same rifle, then we ONLY need to resize the neck section neck section! Anything more is unnecessary reworking of the brass, which will, in time, lead to brass embrittlement and finally failure of the case. Of course, the elasticity can be restored by annealing, But let’s keep it as simple as we can!

If you ONLY neck-size the once-fired cases and ONLY use them in the same rifle, then the cases will last for a long time. And although it is ideal to have a neck-sizing die, if you do not have one, or they are unavailable for that particular caliber, then simply set up your full-length sizing die so that the shoulder is left untouched. I.e. set up as for full sizing, with the shell holder just touching the bottom of the die on the upstroke. Mark the position of the die in the press with a felt-tip pen. Then back off the die about half a turn (which is why it is useful to have the pen marking) but do not clamp it.

Now place a fired case in the press and run it up, while placing a couple of fingers on the top of the die. You should not feel any contact between die and case at this setting. Screw the die in until you just feel it making contact. Raise the die about 1/8 of a turn, run the case down and clamp the die ring. Now screw the die in properly. Since the clamping rings usually cause a slight shift in the die position, you need to check the setting. Use the felt-tip pen to ink over the entire shoulder and slope of the case, let it dry for some seconds, and run it up again. When you remove it, there should be no bright areas showing that the ink has been rubbed off. If so, set the die another 1/8 of a turn higher and repeat. When the ink on the shoulder and slope remains untouched, the setting is OK.

With this setting, you can produce resized cases that fit the rifle in which they were fired as closely as possible without needing expensive equipment. But you must be careful to use those cases ONLY with the same rifle. One shooter of my acquaintance and his wife both use Swedish Mausers. He once went to a competition alone, and erroneously took the case for his wife’s rifle. They did not fit, and the whole trip was an expensive waste of time. So be very careful if you use more than one rifle of the same caliber – keep the batches separate and identify them, or use cases from different manufacturers for different rifles.

One final dimension you must watch out for: case length. It is a bad idea to let the mouth of the case jam in the chamber, as this creates an iron-hard crimp, prevents proper expansion of the case and release of the bullet, and causes an increase in maximum chamber pressure. So check that the resized cases are within the maximum permitted case length, and trim if required. There will be a small amount of stretch, even with the rifle-optimized cases.

[CouldBeWorse]

Ok, I finally received a bolt to try... Except I'm not sure it came off an Enfield as advertised. It's marked "X" instead of E/W/R, there's a serial number stamped on the handle, and slight differences to the extractor:
Attachment 36532
Attachment 36533

[Patrick Chadwick]

Yes that is a bolt off an Enfield - an Enfield P14.
Not an M1917, which is not an Enfield, despite the erroneous popular name of "the American Enfield".

The photo shows the shorter extractor lip and wider bolt face recess for the British .303 cartridge, which has a wider base than a 30-06. Don't even try it in your rifle! The bolt bodies are not interchangeable and the locking lugs are different!

If it was sold to you as being for an M1917, you have grounds for returning it.

[jmoore]

As for neck sizing the 30-06, I only size about 2/3's of the neck, It's enough to properly support the bullet, it helps center the bullet i the throat (kind thoughts and all that), and the shoulder is safe from being pushed back.

If the headspace is on the long side, seating a bullet to engage the rifling with a somewhat reduced charge will help minimize case working on the first firing.

[CouldBeWorse]

Just a little rant: I had purchased two bolts, to see if one might be a thousandth longer and get my rifle to headspace.

The first bolt, advertised on eBay as "1917 Eddystone Enfield Complete Bolt" turned-out to be a P14 bolt; and the second bolt, from a GunBroker seller, arrived today in a parcel weighing a total of 4.5 ounces (including the box).

Arg!