Question about COL and cannelure


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Lord Kimbote
October 21, 2011, 08:57 PM
I just bougt some PVRI Partisan 198 gr. FMJ BT bullets to load for an 8mm Mauser. Though I like PVRI bullets, there is no load data for them anywhere. I loaded a dummy round and used a Lee FCD to crimp on the cannelure. The problem is that the COL is 3.16", which is longer than any load I have seen (though close to a 220 gr.Hornady load).

While the dummy round chambers just fine in my rifle, I am trying to figure out where to start a powder load (Varget). Should I start with data for a bullet of different weight but similar COL? I think the variation is due to the very low placement of the cannelure on the PVRI bullet, and I want to maintain a safe volume inside the case with a seated bullet.

Any input would be helpful.

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rcmodel
October 21, 2011, 09:05 PM
(Assuming you are shooting them in a 98 Mauser or other strong action?)
Do what you gotta do.

American reloading data for the 8mm Mauser is held to very low pressure to start with.
SAAMI MAX pressure is only 35,000 PSI, (a 30-30 Win is 42,000) so you got a lot of wiggle room, even with a max load seated deeper.

rc

Lord Kimbote
October 22, 2011, 01:40 AM
That's what I will have to do, but I am still interested in why the cannelure is placed so low on some bullets (by that I mean there is only a small amount of the bullet below the cannelure) when some bullets seem to be have one placed about half way along the bullet. Is it an efficiency thing (the more bullet in the case, the smaller the volume, the less powder needed)?

USSR
October 22, 2011, 11:41 AM
L_K,

There is no need to crimp, so just ignore the cannelure and seat the bullet with 8mm (.32") of the bullet in the case neck and be done with it.

Don

gamestalker
October 22, 2011, 03:54 PM
If it were me I would seat off the lands .010"-.015" providing it allows enough bullet bearing surface contact inside the neck. Other wise, just seat at the canelure. You can crimp a bottle neck cartridge, by all means, but with a bolt action it is rarely necessary and could end up costing you some accuracy. You could also end up with more head ache when trying to crimp bottle necks, collapsed shoulder's and neck tension issues are often the most common problems encountered when doing this.

Steve C
October 22, 2011, 04:50 PM
American reloading data for the 8mm Mauser is held to very low pressure to start with.

While the domestic commercial manufacturers of 8mm Mauser load to a low pressure level of 35K psi to keep the risk of someone using an old 88 rather than the more modern and robust 98 Mauser rifle the data from Speer and Sierra produce 50K psi for 30-06 equivalent loads. The differences between the lower powered ammo and the JS loadings can be confusing.

For your 198gr bullets I'd use data for a 200gr bullet. You should never use a lighter bullet data for a heavier bullet. Use Hodgdon's (see pic) or other data but note on the Hodgdon data that their start load is at the (old) SAAMI pressure level and is less than a typical 10% reduction off maximum while their max is at a JS level. Set your OAL no longer than the max 3.250" either by using the cannelure or use Hodgdon's published OAL, probably doesn't matter as OAL doesn't affect pressure much in rifle cartridges as long as the bullet is off the rifling when chambered.

As for the start load if using a 98 Mauser then simply reduce the maximum load by 10% and work up.

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