Canhunter35
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168s might have trouble reaching lands on a saami 308 chamber with keeping the boat tail below the shoulder neck junction?
Load Analysis, Your assistance would be greatly appreciated
- Thread starter birdiemc
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DUSTY NOGGIN
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soft chuck up one of the brass you just fired and indicate just below the shoulder , then just look at the runout of the neck ,youll be amazed how bad/different each case is from one another
a hand held neck turner works good , cause your wrists compensate for the 2 axis off center .. but your lathe could be used as a sorting tool because some will be good the way they are
youll need to see before this really stands out , but brass when has out of whack necks , then gets fired it kinda sets the whole neck off axis and a sizer die , doesnt really push it back to good ,really. close but still not on axis ... a turning tool used before any firing may still be off axis , because the first time it was fired it was set there/ off axis . if neck turned , it is turned to an axis of the neck , the next time it is fired it will align the neck axis to the body of the case axis ... because those same 2 areas in the chamber are inline
i think aligning those 2 axis together and creating the most equal neck tension is where i seen the most improvement in my reloads
most people give instructions recommending .002 shoulder bump which actually makes that case fit very tight inside the chamber , because of the shoulder angle acting as a wedge ( like a cone type bearing ) so when closing the bolt that shoulder wedge will lift the neck up hopfully right into the center of bore axis.. if you have case body and neck axis aligned ..
if you did not turn and your neck axis is off a couple thousands . i think it either starts swaging through the rifling off center or absorbs pressure swaging the bullet to center changing velocity
your groups are good though doing what you are doing , 45.2 group looks , based on velocity graph . maybe drop to 45.1
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DUSTY NOGGIN
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15 rounds total 3 each at following charges, 44.6, 44.8, 45.0, 45.2, 45.4
.308 win, Varget, 168 smk,
Not sure what happened on that 3rd shot string but it looks awful, if you take that out the other 2 seem to have a trend,
you want to include the 3rd string , is part of the whole story ... if you take the top picture and plot at 45 still about a 35 ES , could be better
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birdiemc
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Dusty I was just thinking this morning about the process of neck turning and came up with several questions, but you pretty much answered everything for me without having to ask. That clears up a lot for me thank you. Now I got to buy even more reloading equipment....haha
birdiemc
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I have not yet played with seating depth at all, but maybe today if I can get time. Cured 35 lbs of bacon this week so gotta slice and package that up. Ain't too many things in this world that take precedence over bacon at my house.
I dont understand, you mean to try and keep the boatail bear surface below the neck shoulder junction. I don't know how far he's off the lands right now, If he's quite aways off say .040 or .050 i would get out to about .005 and try it no matter what the O.A.L is and see if its better and try working back. Once he achieves the best seating depth a wyatts box may be beneficial there's only one way to find out.
Canhunter35
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This is what I'm talking about. This is a 208eldm .02" off lands. You can't even seat a 168eldm and touch the lands on a saami 308 chamber. There's no bearing surface in the neck
Canhunter35
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Lol You always jump a lot with a 308.
I disagree, seating further out with that short bullet is pointless. He's also maximizing case capacity instead of maximizing case fill which will improve your sd/es. I'm betting if he seats those around 2.8"-2.805" and loaded 44gr of varget he'd mirror the results of his 2.88" and 45gr load and have a tighter group at 1k. IMO
In my opinion try seating out farther and let the gun tell you what it likes and not just assuming something you never know until you try something. That's the beauty of reloading is trying different things often you learn something.
Hiwayman92
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In my experience, it's pretty hard to go wrong with 45 grains of varget in this combination. Another great one is 42.5 grains of IMR4895.
Capt RB
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Does the FGGM shoot well? If it doesn't goto the 175fgmm and see if that shoots well. Once you have a factory load that shoots you have a starting point for seating. My 308 doesn't shoot the 168fgmm well at all. It shoots the 175fgmm the 178 Hornady bthp match and 178eldm @ .5 or better with less than 20es for the box. If I set my seater at the 175 fgmm I can shoot the 168 bergers into very small groups. If I adjust the seater to the 168 load the berger handload at that seating opens up to .75 and the es climbs up. With the short barrel even suppressed the 2 flat spots are 42-42.4 and 44.4-44.8. My rifle is a tight bore so my data is quite a bit different. I run 42.0 of varget with the 168 Berger for alot more speed. Because my bore is @ .298. I can't run much more than 44 or I will drop primers. 44 has craters the moon would be envious of. My pressure at 42 would be close to what your top load was I'm fairly certain of that and it is where my rifle shoots well using M118lr brass 200M primer for the rest of the recipe.
For 178's I use lapua brass 200m 42/varget @ 2.865 in aics mag Shoots bugholes in my rifle. Because of the component consistency load it shoots in many factory rifles also but it doesn't have the speed I get.
For 178's I use lapua brass 200m 42/varget @ 2.865 in aics mag Shoots bugholes in my rifle. Because of the component consistency load it shoots in many factory rifles also but it doesn't have the speed I get.
birdiemc
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I'm definitely going to be jumping quite a bit no matter what with the 168, I dont have the numbers in front of me right now, but I did check with 220 eld-x seated at same COAL to fit in the magazine and I was .160 something off the lands. So the 168 I would imagine is going to be farther back still and I'll run out of neck before I hit the lands.
Right now I'm not compressing the powder at all. You say I'm not maximizing case fill. Are you saying the max case fill (slightly compressed charge) will provide better es/sd? Please explain, I'm trying to wrap my head around it.
I just looked at a saami 308 reamer print it is .090 freebore so I did some math.
2.139 is case to lands
2.073 is CBTO with 168 classic hunter this is boatail bearing surface seated at neck shoulder junction.
So that would leave you .066 to the lands
A 308 neck is .321 long. To touch the lands you would still have about .250 still in the neck. Your OAL would be 2.714 at the neck shoulder junction
Case to neck shoulder. 1.704
Bearing surface .303
Nose length. .707
= 2.714O.A.L
If you move it out .060 2.764
I dont see how you have a saami chamber
2.139 is case to lands
2.073 is CBTO with 168 classic hunter this is boatail bearing surface seated at neck shoulder junction.
So that would leave you .066 to the lands
A 308 neck is .321 long. To touch the lands you would still have about .250 still in the neck. Your OAL would be 2.714 at the neck shoulder junction
Case to neck shoulder. 1.704
Bearing surface .303
Nose length. .707
= 2.714O.A.L
If you move it out .060 2.764
I dont see how you have a saami chamber
