.223 80gr COL question


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madd0c
November 7, 2009, 09:34 PM
Ok, I started loading up some 80gr Sierra MK HPBT along with several other bullet weights to see which shot best in my 1-7" AR.

When I got to the 80gr The hodgdon manual lists the COL at 2.55" but the Spier manual says max COL is 2.25".

The cartridge at 2.55" will not even fit in the magazine.

What are the consequences of loading the 80gr to 2.25? The load I am using is 0.5gr above starting load per Hodgdon reloading data center.(20.5gr) so nowhere close to max load of 22.7gr.

Thanks, madd0c

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Mags
November 7, 2009, 09:39 PM
The 80 grain is designed for single shot use. With a mag in the mag well you will have to drop the round through the ejection port and manually chamber the round each time. Do not change the the minimium OAL to a shorter length you can go longer but never shorter.

madd0c
November 7, 2009, 09:57 PM
OK, that answers that question. Won't be loading up any of those for the AR :(

And, just curious, why can't you go shorter than listed COL since it is alot longer than the spiers manual indicates COL max to be.

NCsmitty
November 7, 2009, 09:59 PM
That's the problem with 223 and 308 rounds, with their short necks and longer bullets you have to compromise somewhere. If you seat too deep, you hog into the powder space, limiting your velocity. If you seat the bullets out, most times they will not fit the magazine, requiring single shot loading.
It happens with AR's and short action bolts.


NCsmitty

madd0c
November 7, 2009, 10:23 PM
NC - the bullet seats fine with this load to 2.25". Should I load these 20 rounds to 2.25' and see what velocities I get or is there some reason that seating the COL shorter than listed would be dangerous?
Thanks for the information guys!

NCsmitty
November 7, 2009, 11:14 PM
I'm not sure, as I do not load heavy bullets in my Contender. Perhaps someone else has experience with the 80gr. What powder are you using?


NCsmitty

madd0c
November 7, 2009, 11:17 PM
IMR-4064 20.5 gr load

taliv
November 7, 2009, 11:32 PM
i'd have to go look, something i don't have time to do at the moment, ... may be wrong on this... but i don't think it's safe to seat the 80g bullets deep enough to fit in the magazine.

please call sierra's hotline before you shoot any of those

madd0c
November 7, 2009, 11:48 PM
thanks taliv, I sent them an email. I definitely won't shoot these until I get a definitive answer one way or the other.

Mags
November 8, 2009, 12:21 AM
It's not that you can physically seat them at that depth its the fact the deeper you seat any bullet the smaller the case capacity becomes, in theory increasing chamber pressure.

bfoosh006
November 9, 2009, 12:06 AM
Neck tension will be horrible at 2.25" , the neck of the case meets the ogive of the 80 gr bullet. You really should check your throat depth prior to loading any of them. Most manufacturers chamber dimensions are different. I'll find a link and post it....

bfoosh006
November 9, 2009, 12:07 AM
http://radomski.us/njhp/cart_tech.htm

madd0c
November 11, 2009, 07:03 PM
For anyone who cares this is a direct reply from the Sierra tech support:

Our suggested COAL for the 223 loaded with 80 grain MatchKings is 2.450" to 2.550" but neither of these lengths will fit a standard 223 magazine for an AR.
It is not safe to shoot the 80s loaded to 2.250" but you may shoot 77s loaded to that length.
Rich


So I guess I will be looking to trade a box of 50 80gr matchklings for 77s :p

Thanks for all the information guys. Glad I took the time to research this further.
madd0c

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