swapping 168 SMK with 165 SGK?

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beerbebud

Inactive
wondering if anyone has ever done this and would it be safe? Ive got several hundred rounds of 168g Federal gold medal match HPBT in .308 was wondering if it would be safe to pull the 168g pill and reseat with a 165 Game King? anyone ever done this im just thinking of ways to save money since ive already got all those MKs on hand.
 
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CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

I think you've got Federal Gold Medal match ammo for either 308 or 30-06. Both are made with the Sierra 168-grain bullet.

The Gameking will have a thicker jacket, tending to raise start pressure a little, but it will be shorter, tending to lower it a little, so this may be a wash if the COL is kept the same.

But I can't know for sure without trying it. So your best bet is to pull 6 rounds and combine
the powder and weigh it and divide by 6 to get the average charge weight for your lot of ammunition. Next load one 10% below that average using your GameKing bullet. Load the next 8% low, the next 6% low, the next 4% low and one 2% low and one with the full average charge. Shoot them in order of increasing change weight, checking each one for pressure signs.

Chances are you'll be fine, but that safety step doesn't use up much ammo and gives you some insurance that all is well.
 
Short answer is i wouldn't do it.
Long answer.
The load data for 165, 168 is usually the same. However that doesn't take into account with standard loading practice of starting with the starting powder charge and working up.
Also you may have issues pulling as the "match" ammo is probably crimped.
 
No, match ammo is never crimped for fear of distorting the bullet. I pulled a number of those GM308M cartridges in the past with no issue.

If you read my description, going to a starting load and working up is exactly what I has him do.
 
I usually use SMKs for .308 bolt gun or M14, but SGKs for M1. Occasionally, I have swapped one for the other, with no load change or seater die change, and noticed no difference. Indeed, for ought I can tell, the SGKs are just as accurate and consistent as the SMKs, at least out to 500 yards.
 
Warning..this worked for my gun and my set up may not work for you:

I actually did just this as a experiment. Using the OCW method I was able to develope a amazing 168 SmK load for my Savage 12FV build and wanted to see what would need to change for a hunting load. End result after safely backing down charge 10% from my 168 match king load....resulted in exact same charge and COAL. Sierra makes very good bullets and they were so close in weight etc that the only difference was a slight POI from the match king load. Which leads a small verification that the OCW science has merit.
 
Change the bullet and you need to work up the load again.
165 and 168 grain data is not the same either. It's close, but isn't the same. You'd really be better buying BNIB brass and working up a load.
You have no idea what the powder is when Mexican Match loading the Federal Match ammo. Isn't unsafe, but you won't be able to repeat the load.
 
Why don't you just shoot the factory match ammo for practice, and then reload the fired cases with Federal 210M primers, 42.5 gr (+ or -) of IMR-4064 and your 165 gr Game Kings and call it good?
 
2ndtimer.

I think he explained that in the first post. He's just working with what he has on hand.


T. O'Heir,

Normally, what you said about powder would be true, but Federal has published about its use of IMR 4064. They buy it special and I infer they buy it with a tighter burn rate tolerance than what we buy in canister grade, based on the charge weight in GM308M having stayed the same for decades. They also get a flash suppressant added because they use it in the Mk.316 mod.0 sniper round they make for the military with the 175-grain SMK. If you search the web, there is an ATK presentation in PDF format that has that information in it. So this is an exception in which we do know exactly what the powder is.
 
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