Help with .223AI Throat

[longrange2]

I just picked up a .223AI Bartlein barreled action with only 200 rounds fired so far, and built by a fairly well known shop. This rifle seems to have a very long throat. I expected it to be throated for heavier bullets, but the 75 grain AMAX doesn't have a full bullet diameter of bearing surface inside the neck of the case and will barely fit an AICS .223 mag. The OAL when touching the lands is 2.555

The 77 grain Sierra is somewhat better but the 69 grain Sierra almost falls out of the case. I know that the throats are cut longer on many .223AIs to maximize powder volume with heavier bullets, but this seems excessive. The smith said don't worry about seating depth, just seat bullets to base of neck and shoot. All of my other custom rifles I am typically only 0.005 to 0.025 off the lands.

Before I waste a bunch of time and components I was just wondering what throat lengths others have and how they shoot.

 

[Nude nut]

I just picked up a .223AI Bartlein barreled action with only 200 rounds fired so far, and built by a fairly well known shop. This rifle seems to have a very long throat. I expected it to be throated for heavier bullets, but the 75 grain AMAX doesn't have a full bullet diameter of bearing surface inside the neck of the case and will barely fit an AICS .223 mag.

The OAL when touching the lands is 2.555. The 77 grain Sierra is somewhat better but the 69 grain Sierra almost falls out of the case. I know that the throats are cut longer on many .223AIs to maximize powder volume with heavier bullets, but this seems excessive. The smith said don't worry about seating depth, just seat bullets to base of neck and shoot. All of my other custom rifles I am typically only 0.005 to 0.025 off the lands.

Before I waste a bunch of time and components I was just wondering what throat lengths others have and how they shoot.

What twist barrel if it a 7 try 80.5 berger or a 90gr berger vld or try longer jump as stated by you smith.
Sorry I missed you are using a magazine.
Cheers Trev.

 

[ab_bentley]

I just picked up a .223AI Bartlein barreled action with only 200 rounds fired so far, and built by a fairly well known shop. This rifle seems to have a very long throat. I expected it to be throated for heavier bullets, but the 75 grain AMAX doesn't have a full bullet diameter of bearing surface inside the neck of the case and will barely fit an AICS .223 mag.

The OAL when touching the lands is 2.555. The 77 grain Sierra is somewhat better but the 69 grain Sierra almost falls out of the case. I know that the throats are cut longer on many .223AIs to maximize powder volume with heavier bullets, but this seems excessive. The smith said don't worry about seating depth, just seat bullets to base of neck and shoot. All of my other custom rifles I am typically only 0.005 to 0.025 off the lands.

Before I waste a bunch of time and components I was just wondering what throat lengths others have and how they shoot.

From what I can say from my testing, is it doesn't matter as much as one would assume. I run 75 in the middle of the neck and have been impressed with accuracy beyond 500yds. Even some really small groups past 700yds.

Adam

 

[longrange2]

Its a 1:8 twist and I am using AICS mags, max COAL in those mags is 2.555

 

[Nude nut]

Its a 1:8 twist and I am using AICS mags, max COAL in those mags is 2.555

The 80.5 fullbore bergers will be fin in 1.8 the are very tolerant to jump or in the lands my 223 has .100 freebore my oal is not much under 2.500 and thats 10 thou in the lands and just above the shoulder neck junction.

Cheers Trev

 

[fredo]

Same boat as you, just got a .223AI 2nd hand & not sure the exact FB. Measured a 75Amax @ 2.455", to jam. I'm runnin' them @ 2.450, and they're shooting very nicely, with no load development...just forming brass. Bodes well for proving a finished load...

If you're a full tenth longer to lands, that does seem long? Did the seller give any inclination as to why he sold it?

Only way to know if it'll shoot, is to shoot it...

 

[Longtrain]

My AI has a .095 throat and I shoot 69, 80 SMK's and 80.5 Bergers for matches. The 80's are single loaded, but I run the 69's from the mag. The rifle is a Tikka 595 and the mags allow a much longer round then standard AR mags. I usually jump them about .025.
If you can't get a reamer print, you may want to cast the chamber with cerrosafe to get some good dimensions of your chamber, much better then guessing.