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wssm/wsm erosion problems continued

remington nutremington nut Member Posts: 961 ✭✭✭✭
edited March 2004 in Ask the Experts
Stalion... although the topic was locked i'd like to open it and put my 2 pennies in the pot to see if i can help any ..... what your gunsmith might have been trying to say when he said headspace erosion wasn't entirely wrong.... when you have overbore calibers... the case is alot bigger than the bullet.... hence pushing a big ball of fire down a small bore you can devolp throat erosion in the throat of the barrel... now when your have throat erosion... the headspace changes on the gun... growing longer as more of the throat is eroded away.... i have a .264 win mag... famous for throat erosion.... just something about sending a 264 diameter bullet out fo a 458 case body does that to the barrells lol

so in conclusion what he said sounds like a different name for the same problem.... headspace erosion/throat erosion
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Comments

  • v35v35 Member Posts: 12,710 ✭✭✭
    edited November -1
    Throat erosion takes place forward of the front of the case and the chamber. Momentarily,at the instant of firing, as a bullet is leaving the case and before it reaches the groove diameter, sealing off the barrel, gas gets around it, eroding both the the very rear of the groove diameter and the start of the rifling. This is a progressive phenomonon.
    A breechbore gage is a tapered rod used to measure the advance of this erosion. Headspace should be unaffected as the cartridge brass is expanded, sealing off the whole chamber against escaping gas.
    An eroded throat is enlarged to over the bore diameter and the start of the rifling has rounded lands and is further forward in the barrel. To the eye it looks finely pitted.
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  • nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    Remington nut,

    I have to leave for the airport but I wanted to get a couple of thoughts in first.

    - There is no such term as headspace erosion.
    - Guessing what his gunsmith was trying to say is exactly that,
    guessing.
    - Throat erosion is a real term but has absolutely nothing to do
    with headspace.
    - Headspace is measured from the boltface to a DATUM LINE on the shoulder of a bottleneck cartridge. The shoulder does not move forward with throat erosion, the throat does. Therefore the erosion has nothing to do with headspace.
    - As was mentioned before, there can be lug setback which can and does affect headspace.

    I've got to run, but I'll add a little when I get back.

    Best.

    31 MAR 04

    ...when you have overbore calibers...

    There is no such thing as 'overbore calibers'. A cartridge can be overbore but not a caliber. Nowadays, lots of cartridges have moved out of the realm of overbore due to increased number of new formulas for powders that burn completely within the barrel as opposed to the older, slower powders that didn't burn completely.

    This might seem to be a little terse but either his gunsmith doesn't know what he was talking about or he was babbling in confusion. No offense is meant.

    Best.
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