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Spencer54

K98 8x57 Mauser

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Wondering if you can give me steer on where I go from here.

I'm shooting a K98 and using Lovex SO62 - according to Lovex I should be seeing 2500 fps.
According to my Magnetospeed I'm at 2300, using the exact bullets they list S&B No. 2910 @ 196 gr.

https://explosia.cz/app/uploads/2016/11/reloading_Lovex_EN.pdf

After firing my home loads next to PPU Match 8x57 they feel down on power in comparison, they certainly shoot lower.

According to the books I'm at max, but it sure doesn't feel like it.
From here am I better off looking at a crimp, or reduction in COAL - or just keep on going up in increments?

 

Thanks in advance

 

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Reloading data from manufacturers is only a guide, not an absolute. Usually, it is what they got on a given day using their equipment, LOT # of components, and assembled on their equipment. Crimping is always a good thing (to me) but chasing data numbers can be a losing proposition. They could be using a 600mm test barrel with an exact .323" groove diameter CIP spec chamber. Your K98 could be .326" with a military chamber. Do what you think is safe after you verify the speed with another chrono.~Andrew

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Thanks I'll step up the powder and see how it goes, I'll get some factory 8mm and chrono that as well - that way I'll have some reference.

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In the US, 8x57 factory ammo is highly anemic due to the one time prevalence of Model 1888 Commission Mausers . This left me with nothing to go by when running sporting weight heavies in my 8mms.  My deer load for my 648 Husqvarna is a 208 grain cast bullet at just under 2400 fps. Accurate and lethal.~Andrew

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QuickLOAD also says 2,500 fps or thereabouts for 47.8gn SO62 under this bullet in a 23.5 inch barrel (actually 2,540 fps from 49,728 psi, right where you want to be).

However ........... I was dipping into the 1,000 plus page compilation of the late Ken Waters' Handloader magazine articles over some 30 or so years of his handloading tests and lit upon his 8mm Mauser IS article originally published way back in November 1975 and mostly using the then Dupont IMR powders including 4064. (SO62 used to be called AAC-4064 in its old Accurate Arms persona and was sold as an alternative to the venerable US manufactured product. QL confirms this with 47.8gn of IMR-4064 computed to produce 2,549 fps / 50,950 psi PMax.)

Now, Ken Waters found using two different K98s (1933 DWM and Czech VZ-24) back in 1975 that his actual results were WAY down on what loading manuals prediced from their maximum loads - as much as 200 fps with 150 grainers for instance. On the other hand RWS sporting ammo chronographed very close to what the manufacturer claimed - and at much higher MVs than his handloads produced. Waters was so concerned by this he paid for the H.P. White laboratory to independently chronograph the RWS ammo and some of his handloads and they confirmed his findings.

He worked loads up to higher levels than in any of the manuals to reach the expected MVs (and what the German commercial stuff gave) and with the US IMR version of the powder got up to 50.0gn 4064 with the 196gn Norma RNSP for 2,539 fps MV. Waters did warn this was absolute maximum based on measuring case expansion! (QL predicts an over-CIP max pressure result from both SO62 and IMR-4064 for this with the 196gn S&B. For SO62, it says 2,654 fps and 58,065 psi)

There is then an addendum to the Handloader article saying Dupont had got in touch after it was published advising some of his loads were over-pressure in their pressure test barrel, so he warned readers about being very careful in using his data. But he couldn't explain the dicrepancies between the loading manuals / Dupont loads / MVs and his findings, finally putting it down to maybe throat wear on 40 year old used military rifles.

I suspect it is more to do with how barrels were throated. The Germans developed the 7.92X57mm IS heavy bullet loading during WW1 as an MG cartridge, but it was marginally unsafe in rifles. When the WW1 era rifles/carbines were redesigned into the KAR98k in the late twenties/early 30s a decision was made to use the 198gn sS (Schwerer Spitzgeschoss) MG round as the universal German military loading and the rifle chamber was redesigned with a long tapering throat to reduce pressures - 1 3/8 inches according to Waters. (Wow! That IS a 'freebored' chamber!) Those countries / factories that produced K98 type clones were also designed around the sS round and presumably copied the German chamber.

I suspect the powder manufacturers' test barrels do not have anything like this degree of freebore. QuickLOAD's equations  rely too on the bullet being at the rifling at whatever COAL is input and its results overstate pressures and velocities for those that have been 'freebored'. (To use a now out of fashion term in its original sense of having a massive designed inbuilt jump to the rifling. It was also an integral part of Ken Weatherby's 'magic' to achieve his cartridges' claimed MVs within high but acceptable pressures. My first ever loading guide was ICI Nobel's little paperback and I remember wondering what this 'feebored chamber' was in relation to one of the Weatherby cartridges. Nobel warned the data was only applicable to 'freebored rifles' and had to be significantly reduced for those with 'normal' chambers.)

So, all this leaves you just where? Where you are is that you need to beg borrow or steal a chronograph and see what you are actually producing in your barrel / chamber. If, like Ken Waters' findings, you're a couple of hundred fps down on what the loading guide says, you can carefully work loads up a bit using a chronograph throughout the process.  Without such data, you have to stick to Explosia's maximum for safety.

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