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Satterlee load development method

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I've just started on a load for my 6.5CM i'm using 139 grain scenars  Lapua sr cases and muron kvb 223  primers and the powder is Vit N160

Started at 41 grains up to 42.8 grains in increments of .2  my fps was all over the place and i could not see a sweet spot, is this down to bad case prep/ new brass? I expected to see a slight increase with each .2 increment however i was seeing higher fps with lower charges and my cases were coming out sooty, i was not seeing pressure signs, according to QL im near max at 44 grains.

i have done a load using 100 grain Amax with RS52 and this shoots fine and i found the sweet spot no problem,  with single figure SD but it seems i'm having a bit of trouble with this.

 

first run    second run   powder charge         

2466             2516         41.0

2520            2529         41.2

2503            2548         41.4

2505            2570         41.6

2533            2548        41.8 

2518           2577         42.0

2534           2592        42.2

2562           2574        42.4

2532           2609        42.6

2565           2640        42.8

 

HELP!!! 

TIA

Kevgun

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The KVB 223 primers are not suitable for the high pressure loadings of small rifle 6.5 CM brass.  It's best to use one of the many magnum primers such as KVB-223M or CCI-450 or Federal 205s.

Also, QL does not map for small primer cases.  It assumes higher energy larger primer cases so beware...results will be under what you need to be using.

Also, you need to bear in mind that the published load data is not for small rifle primers, it's for standard cases AFAIK using standard (higher energy) large rifle primers, so you need to up the loads from the data given.  I found that using RS62 that it was taking 44.4gr to achieve what some people got using LR brass and 43gr loads.  It will vary from rifle to rifle but rule of thumb seems to suggest you need to be almost a grain up on published loads.  As always start low and work up, and if using Magnum primers don't rely on seeing pressure signs on the primers...they're more likely to pop first, so look for extractor marks on the case head instead.

Your sooty cases seem to back up what I have said above...you're not getting proper obituration which might also explain why your velocities are a little random.  In your shoes I'd definitely up the loads and start again using a "Satterlee ladder" or OCW test.

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Thanks VarmLR, My Rifle is a Tikka T3X Tac A1, I will run the test again changing the primers and go up a bit and report back.

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Interestingly, Vhit give max load for N160/139 scenar as 42.1gr and min load as 33gr which seems very odd to me...start load seems very low at 25% under max!

Others may be able to better help RE N160 and SR primer cases, but I would expect loads of 42 to 44gr may give better results.  I use the same rifle and 44gr of RS62 give around 2630fps with that bullet and shoot bug-hole groups. RS has a similar burn rate to N160 but a slightly different bulk density though so loads are not directly comparible.  N160 is 920g/l and 3650J/g compared with RS62 at 3750j/g and 960g/l so this might further indicate that with my safe loads in the same rifle, your Viht loads look to be quite/very light.

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I haven’t loaded any rounds yet but have a 6.5 creedmoor waiting for me. I have to say N160 is not a powder I would be looking at. I am considering N150 which from research appears to be a more commonly used powder. 

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N150 does seem to be the more commonly used powder and shares the same burn rate as Reload Swiss RS62 and almost the same bulk bulk density.  Oddly though Viht give it as delivering slower velocities than N160, which doesn't seem to be the experience of most using it.  I would expect similar loads using N150 as RS62 but Vihts data suggests much much lower loads....something seems a bit "off" there?

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All of this case prep and assembly effort seems to be completely lost by firing only two rounds and concluding on the best charge weights for further development.

A repeat of all of the rounds fired would no doubt result with different results! 

... in my experience of a few thousand rounds fired through NATO EPVAT systems. :) 

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Does EPVAT testing include reloaded cases?

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I thought that this was specifically related to pressure testing of military ammunition for consistency/quality and nothing to do with reloading cases?

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Pressure, velocity and action time.

It doesn’t matter if the cases have been reloaded or not, as long as they’re consistent throughout the batch. 

There are a lot of variables within the round which you cannot truly control and two rounds is not nearly enough to establish all of the results which could occur. 

 

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Done some more testing today on VarmLR advise, i worked the charge up in.2 increments from 42.8 to 44.6

velocity increased shot on shot with a node at 44.4 gr and another about a grain below no sooty case as before swapped primers to KVB223M using N160  no pressure signs what do you think? 

Graph1.jpg

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44gr to 44.4 looks good and is on a plateau. I'd load up 5 at 44.2 and check ES/SD and group at that.

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