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Discussion Starter #1
Picked up a box of Nosler 223 77gr HP match bullets at recommended 2.260 oal and tried some rounds in my 185 series Mini 14 with replacement bull barrel and got over pressure indications, ie. stuck bolt. Tried same round in a ar15 223 Wylde chamber with no problems.
What OAL would you guys recommend for .223 chamber for this bullet? TIA
 

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My guess would be that the Wylde chamber has different dimensions, but I wouldn't want to guess, I would rather measure. Longer bullets can raise pressures from being seated deeper into the case causing a higher loading density due to less room for the powder, or the longer bullets can jam the bullet into the lands, which will also raise pressures. No idea what the difference is between the chambers and throats of the two rifles you mentioned, but if it were me, I would measure the cartridge and chamber dimensions and work up the loads only for the rifle I intended to shoot those cartridges in. Good luck, and let us know how it goes.
 

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Discussion Starter #3
Thanks for replying, Oletimer. The Wylde chamber is a regular 223 chamber with an extended .224 throat that lets both 223 and 5.56 ammo to feed with increased accuracy for both cartridges without the high pressure problems of a regular 223 chamber. My problem is I need a correct over all length for the 77gr match bullet for 223 rem cartridges to feed and fire in my Mini 14 without the high pressure problems of a 5.56 cartridge. Start loads using 748 with that bullet is 23.5gr with a max of 25.5gr with a listed length of 2.260, which is WAY too long for my Mini.
 

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Are you loading to 223 specs or 5.56? Either way you can develop a round specifically for your Mini 14. Take an empty case and put the bullet in it leaving it longer than the spec COL. Insert the cartrige into the chamber allowing the bullet to be pushed back into the case. Carefully pull out the round and measure that COL. Work up your loads with a COL a couple of thousandths less than what you measure.
 

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Any by the way, there are no pressure problems with a 5.56 round- only the mis-application of using a 5.56 round in a 223 chamber. You can use 223 in a 5.56 but not the other way around.

You do not give us much to go on here. Do you know the velocity of your handloads that are showing signs of overpressure? What kind of powder are you using and how much?
 

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Discussion Starter #6
Thanks for asking about the load, Maineiac. Going by the Sierra manual the load for that bullet using 748 for ARs is 22.7 start to 23.4 max and for bolt guns is 20.4 start to 22.9 max, both at 2.260" OAL. The load I tried was 23.0gr 748 at 2.260" OAL. I tried 3 rounds in the Mini chambered for 223 and promptly got it locked up on first round, after 3 rounds I STOPPED using that load in the Mini.
I then tried it in my AR chambered for 223 WYLDE, and had NO problems with that load.
Looks like I just answered my own question! Looks like I need to pull what few rounds I have and re-think what I'm doing. Maybe even stop using that bullet in my Mini!

IF anyone else has suggestions, please add them.
 

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.223 vs 5.56 NATO

A true .223 chamber is tighter than the NATO 5.56 chamber. The NATO chamber was "looser" to accommodate FA firing and carbon buildup. NATO rounds are hotter than .223, one of the reasons is, internal case volume of 5.56 is sligtly less than .223 because the walls of a 5.56 cartridge are thicker. The external dimensions of .223 and 5.56 are the same.

Loading long for caliber bullets can be iffy in semi auto guns, especially a mini-14. Assuming the replacement bull barrel is a true .223 chamber spec, it's probably too tight for heavy bullets not meant for the mini-14. The bolt on the Mini could also have a problem with headspace causing a problem for long bullets but not a problem for 55gr-62gr bullets.

There's a bunch of things that could be going wrong, chamber, bullet, powder, etc. It's not really one thing that can be "blamed" for the problem, but there is one thing you may consider doing to fix it. Have the bull barrel reamed to .223 Wylde or NATO spec to give the longer bullet a little more wiggle room. If I were you, I would also consult a real gunsmith, instead of taking the word of this keyboard commando. I am not n expert, I just have my ideas about what's going on with your situation.

Side note: If you are pushing 77gr pills, the twist on that barrel should be 1:7.

Groggily typed at 0400, not checked for accuracy.
 

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Discussion Starter #8
Thanks for that, Scorpio. I think you're right about a bunch of things that might be causing the problem. That barrel does have a 223 chamber with 1/9 twist, I just wanted to see if that twist did in fact stabilize the 77 grainers or not. So maybe I should just stick to 62gr or lighter bullets and save the 77grainers for the AR with the Wylde chamber.
A while back I did talk to a gunsmith about have it reamed out to "Wylde" dimensions, but he wanted $300 for the re-chambering. Given the times, maybe I ought to have it done so I can shoot ALMOST anything in it.

P.S. Hope you didn't lose too much sleep, matter of fact you're likely still in bed as I type this!
 

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he wanted $300 for the re-chambering.
For that amount, you may as well just buy a new barrel chambered in Wylde.

I think 1:9 may, and I stress MAY, stabilize 69gr OTM boolits. It's worth giving it a shot (ha ha pun)
 

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A 1:8 barrel is all you need for up to an 80gr 223 bullet. I shot 80gr Sierra, Nosler and Berger BTHP bullets accurately out of my match grade AR15 with a Wylde chamber for several years in NRA & CMP competition.

2.26" is the correct AOL for 223, so I have no idea why the OP is showing high pressure signs.

Was your new barrel and bolt headspaced correctly?
 

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BTW, My mini-14 shoots the 68gr & 69gr bullets very accurately with the standard 1:9 twist. I use H4895 for all of my 223 loads.
 

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Discussion Starter #13
A 1:8 barrel is all you need for up to an 80gr 223 bullet. I shot 80gr Sierra, Nosler and Berger BTHP bullets accurately out of my match grade AR15 with a Wylde chamber for several years in NRA & CMP competition.

2.26" is the correct AOL for 223, so I have no idea why the OP is showing high pressure signs.

Was your new barrel and bolt headspaced correctly?
About a year ago I picked up a box of 5.56 55gr ammo and pulled a bone headed stunt and shot them in my 223 Mini with the usual result, a broken bolt! Found a replacement on ebay and when I got it I took it in to the gunsmith and had him run go-no go guages through it, he told me it was good to go. Have run regular 55gr bullets through it using 26gr 748 at 2.22"OAL with no problems. My guess is that 2.26" OAL with the 77gr. is just too durn long for my chamber! Then again, maybe 23gr 748 with the 77grainer at 2.26"OAL is just too much for my Mini 14.
 

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The 68/69gr BTHP bullets should be fine in your Mini 14.

I think it was already mentioned here, but maybe the throat on your Mini 14 doesn't like the shape of the ogive on the 77gr bullet.
 

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Discussion Starter #15
The 68/69gr BTHP bullets should be fine in your Mini 14.

I think it was already mentioned here, but maybe the throat on your Mini 14 doesn't like the shape of the ogive on the 77gr bullet.
That very well may be true! Just need to look around for lighter than 77gr bullets that will work.
 

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Discussion Starter #16
The 68/69gr BTHP bullets should be fine in your Mini 14.

I think it was already mentioned here, but maybe the throat on your Mini 14 doesn't like the shape of the ogive on the 77gr bullet.
That very well may be true! Just need to look around for lighter than 77gr bullets that will work.
 

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That very well may be true! Just need to look around for lighter than 77gr bullets that will work.
I'll check my bullet stash this weekend. I might have around 250 of the Sierra 69gr BTHP in my reloading room. I'm not shooting them any more because I gave up competitive shooting several years ago. I'm willing to sell them to you for a fair price.
 

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Discussion Starter #18
I'll check my bullet stash this weekend. I might have around 250 of the Sierra 69gr BTHP in my reloading room. I'm not shooting them any more because I gave up competitive shooting several years ago. I'm willing to sell them to you for a fair price.
Gofer it, I'll bite.
 

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