seating 175 smk long

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the stock for the .308 win i am building was cut for a wyatts extended box magazine. the inside diamater is 2.990" which means i can load col about that length. would there be any advantage such as velocity to have the chamber throated for the 175 smk seated to this col? do you see any problem with accuracy if they are loaded to this length and seated .010" off the lands.

 

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anybody?

 

[BigSkyGP]

I can't remember off the top of my head, what the usual COL for 308 is. I can't get to my load manual at the moment.

I would throat the barrel, to touching the lands at 2.99. Then work up your load using the ladder test. After you find max powder load, and accuracy that way. You will load COL adjustments to find more accuracy.

Snipers hide has an excelent post on loading for accuracy.

 

[BigSkyGP]

I would look at some of the established match chamber/throat dimensions. For example the Palma Match, that one won't work for what you are trying to accomplish with the 175 MK, it would be too short. I think that you can get the idea, there are other ones that are probably more what you are looking for.

 

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when i was talking to my gunsmith he was telling me to go with 308 match. he said it is tighter tolerance than the normal win which is good for military rifles. i got the idea of loading long after reading of people loading 208 amax long and pushing the throat way out. this would increase case capacity and lower chamber pressure for certain loads. is the 175 smk long enough to load out to 2.99" and would this make it possible for higher velocity for the 175 smk withing safe working pressure? is there any reason to do this or should i just stick to regular mag length. thanks.

 

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anyone?

 

[Kevin Thomas]

You need some clarification on the "308 Match" reamer, as there are several different versions out there. I had one that was supposed to be set up for LC Match ammo (M852 and M118LR), which never gave particularly good results out of bolt guns. May have been great for an M14, but just wasn't the ticket in any of the several bolt guns I had chambered up with it. I always got reliably good accuracy out of a 308 Obermeyer reamer, with a wide range of bullets, 150s through 190s. The Palma reamers, which have already been mentioned, are very short throated. Great for shooting 155s in guns that are dedicated to that game, but not nearly as versatile as the Obermeyer.

 

[arrow]

thanks for the help so far. i was going to firefore all brass anyway then set the fl sizer die to just bump the shoulder back .002" if this is happening, does it really matter what kind of reamer is used if the throat is cut to a certain depth? what i am trying to figure out her is is there any advantage to shooting the 175 smk seated to 2.99" instead of the standared 2.8 or so inches? would there be a great increase in the ablility to load hot? also is the 175 smk long enough to seat out to 2.99" with good neck tension? thanks

 

[Kevin Thomas]

Arrow,
it seems like you've got some questions a bit jumbled here, or else I'm missing something somewhere. You're discussing headspace issues when we talk about bumping shoulders back, but the seating to match the throating is a spearate issue entirely. Yes, seating to a longer OAL would theoretically give you more powder space in the case. Whether this is enough to be noticed in the field, I have my doubts about that. Standard OAL for the 308 Win is 2.850" as a max, and yes, you should be able to load out to 2.990" and still have some grip on the bearing surface. You may or may not have tension problems, depending on how you're using this ammo. Howver, I seriously doubt that the added capacity you create by doing this is going to be worthwhile compared to the potential problems.