220gr Sierra HPBT for .308 Win

3

308Loader

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Picked up some 30 cal 220gr sierra MK HPBT (#21662) to possibly use for 300 black out loads. Got to thinking about using it in 308 Winchester 1-10 twist 24" barrel.

My research seems to point to this as being a bad idea. Sounds like not enough case volume or fast enough twist to stabilize this weight. Any one ever tried a 220 HPBT in 308 win? Besides the slower twist rate (1-7 VS 1-10) why would it not work? Hornady book shows a 220 ELDX load for 308 Win.

I have no particular need to use this bullet in a 308, thought just crossed my mind and figured I would ask you good people :) Thanks in advance for any constructive input.
 
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200 grain bullets in 308 Win cases over 48 grains of IMR4350 shot through 1:11 twist barrels has won matches and set records. Tested about half MOA at 600 yards in my barrels.

A max load with 220's is probably 47 grains. The barrel's 10" twist is therefore about perfect. I shot a few Sierra 220's in my 308 1:11 26" with that load that shot good.

May need to use a drop tube to get powder packed to fit your cases as I used 150 grain weight WCC58 match cases.
 
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200gr I can find data for, 220 SMK not so much in 308 Win. what do you think for start charge? I have 4350-4064 and Varget on hand. OAL 2800-2810?
 
43 - 44 grains of IMR4350 to start. 4064 and Varget are way too fast for 220's. Seat bullets to just touch the rifling.
 
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Thanks Bart, will check it out and maybe toss 3 downrange tomorrow. Will need to make measurements with this bullet to lands of my rifle to know where to seat the bullet. 2 to 5 thou off of 10 measurement average, correct?
 
308 Win with a 30" 10T Bartlein: Lapua Palma 308 Brass Fed primers, 42.0 Varget with the 200.20X Hybrid (This is a single-shot action, and is long throated) at 2620 fps
 
308Loader said:
Thanks Bart, will check it out and maybe toss 3 downrange tomorrow. Will need to make measurements with this bullet to lands of my rifle to know where to seat the bullet. 2 to 5 thou off of 10 measurement average, correct?
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I soft seated my bullets long enough to set back about .005" when rounds were loaded
 
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 assumes any liability for any damage or injury resulting from the use of this information.
If you want published data and (very) accurate ammunition in 308 with 220 grain bullets I think you are S.O.L. (Shucks, Out of Luck).
I do have a 308 rifle, and do have 308 220 grain bullets. Not OTM, but Sierra GK RN. I also have a jug of WC872, which burns about as fast as charcoal.
But that will need Quickload to predict, and a booster in a duplex load to ensure ignition and complete burning.
I would not expect a flat trajectory.
 
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Marco Califo said:
I do have a 308 rifle, and do have 308 220 grain bullets. Not OTM, but Sierra GK RN. I also have a jug of WC872, which burns about as fast as charcoal.
But that will need Quickload to predict, and a booster in a duplex load to ensure ignition and complete burning. I would not expect a flat trajectory.
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Duplex loads are often dangerous and usually give poor accuracy due to big velocity spreads. Does Quickload calculate duplex load pressures?

220 grain bullets in 30-40 Krag rifles produced match winning accuracy in long range matches over a century ago.

So has 250 grain Sierra HPMK's shot from 308 Win cases more recently. 2150 fps from a 1:8 twist barrel. Best wind bucking 1000 yard 308 load ever. Without a flat trajectory.
 
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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 assumes any liability for any damage or injury resulting from the use of this information.
I do not have Quickload. It does not list WC872, which was from pulled down 20mm Vulcan. It is slower than all commercially available powders. This slowness is a built-in pressure regulator. You have trouble getting all of it to even burn. I do not believe QL can predict duplex load results. I have tried WC872 in 308, with the 220 gr RN. With no booster, it leaves a trail of black bits down the bore. It did go Bang, or, rather boooom with a slow push recoil. I did not try adding the booster. For duplex loads in military calibers, the booster is generally up to 3 grains of your choice powder (Unique, 3031 are mentioned) until it does not leave a trail of black bits.
I actually DO NOT recommend fooling around with slow cannon powders and duplex loads. There is no payoff.
All "published" (with a disclaimer) data available is here:
http://www.castpics.net/LoadData/Surplus/Datapages/308.htm
I also do not recommend 220 gr bullets in 308.
 
What about subsonic 308 load with 220gr SMK? just a thought, no real reason to do such a thing. Probably wont stabilize in 1-10 twist?

I suspect I would need to aim at the moon to lob one 100yrds.
 
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308Loader said:
What about subsonic 308 load with 220gr SMK? just a thought, no real reason to do such a thing. Probably wont stabilize in 1-10 twist?

I suspect I would need to aim at the moon to lob one 100yrds.
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Yes, aim at the moon when it appears way less than 1 degree above your target.
 
One thing Finnish experimenters have mentioned for subsonic is loading boattail bullets backward. It uses up a lot of space in the case so you can work with a smaller load. Ballistics are bound to resemble what a trebuchet achieves. It theoretically adds a little static stability to what your twist achieves by putting the bullet's center of pressure behind its center of gravity.

QuickLOAD always assumes you're using the mildest primer made. The only way it allows for simulating hotter ignition is to increase start pressure above the default. Same for bullets seated in contact with the lands. For contact with the lands it has you add 7200 psi to the default start pressure (default is 3626 psi for cup and core bullets). That raises peak pressure almost 20%, which correlates well to measurements of no-jump vs. jump of about 0.030" with tangent ogive bullets.

Marco's link goes to a WC860 load. Another one not adopted commercially.
 
As mentioned above, 220 grain bullets shoot fine from the 30-40 Krag. I shoot one competitively with the 210 grs Lyman 311284, but that's a cast load.

308 is +/- 1 gr capacity different from 30-40, but rated to much higher pressure. H4350 will be best. See if you can get 42 grs and the bullet seated off the lands, and work up from there to pretty much the max you can fit. It will spin. Not sure why you'd want 220s in 308, but to each his own.
 
Not sure why you'd want 220s in 308, but to each his own.
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A good reason to use 220's in a 308 is when the 308 is the only cartridge and any bullet is allowed in a Palma match. They'll buck the wind better than lighter bullets. That's why David Tubb chose 250's in a 30" barrel to shoot the best Palma match scores on a windy range. They were shot at 800, 900 and 1000 yards.
 
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DockRock said:
308 is +/- 1 gr capacity different from 30-40, but rated to much higher pressure. H4350 will be best. See if you can get 42 grs and the bullet seated off the lands, and work up from there to pretty much the max you can fit. It will spin. Not sure why you'd want 220s in 308, but to each his own.
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Varget is a top powder for F-TR shooters (308 Winchester) using 180's-230 grain bullets, and the Nationals (1000 yard F-TR) was won using N-150 with the 200.20X Berger.
The heavier bullet/higher BC for F-Class is all about windrift. It is a score game where the X-Ring is a half MOA in diameter (5" at 1000 yards). 200 grain bullets are more popular though.
 
"Yes, aim at the moon when it appears way less than 1 degree above your target."

LOL! I meant subsonic at distance. I've read that others do use 210-220's for the wind bucking properties at extreme distance. That's what got me thinking about trying a load. Haven't had time to do the all of necessary home work yet. but thanks bart for affirming that it is a thing, and not a complete crackpot idea.

Like I said before and will say again to those that cant wrap their heads around the why of the question. I have no real need to try this, but I have some bullets, some powder, primers and cases. begs the question why not? that is the only reason I ask.

Thanks for the input all, keep it coming. ill post some results if/when I load some. At this point I think it's more like when:) than if.
 
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