AR barrel throat depth

[beastep]

Im doing load development on a BCA 20" non 5R barrel my girlfriend got me for Christmas and after a few problems and a lot of troubleshooting I finally figured out the length of the throat on this barrel is quite short. Short enough Im getting into the lands on everything loaded to book at 2.245 and also factory loaded Hornady 123 SST. I thought it was just my barrel but a buddy came by yesterday to bed his barrel and we checked his throat length and it is just as short as mine. Im having to load way short, around the 2.20 mark, to get them off the lands on my barrel. His is a Saturn Liberty SS 18" 5R barrel. Is this common for a Grendel? I have a hard time wrapping my head around the fact these chambers are cut to a spec that allows factory loads to get buried in the lands.

[maxxmojo]

I know that my AA barrel has a shorter throat than my Lilja barrel, but it's not that short. Wanna say it's around 2.35ish range.

[Drillboss]

It's not common for a properly cut Grendel chamber. I've had my hands on 5 Grendel barrels and factory Hornady ammo didn't get into the lands on any of them. A round dropped into the chamber will fall free when the barrel is turned muzzle up, with no engraving marks on the bullet.

I'm surprised the Liberty barrel has the same problem. Their Grendel II chamber has a deeper throat than SAAMI spec.

[beastep]

I was pretty upset about my BCA barrel then that Liberty barrel turned out the same way. These are the only 2 Ive ever had my hands on to check. They are also supposed to both be Grendel II chambers.

I been to Enid a few times by the way.

[Drillboss]

And I've spent some time in Garvin County. My grandfather ran a gas plant in Katie and I worked out of Velma for a few years.

Liberty's Grendel II and BCA's Grendel Type II may or may not be the same thing. I haven't seen confirmation of what BCA's chamber really is. At any rate, from looking at the reamer drawings, a Grendel II (Liberty) throat should be about a tenth of an inch or so deeper than in a SAAMI chamber.

[Drillboss]

Im doing load development on a BCA 20" non 5R barrel my girlfriend got me for Christmas and after a few problems and a lot of troubleshooting I finally figured out the length of the throat on this barrel is quite short. Short enough Im getting into the lands on everything loaded to book at 2.245 and also factory loaded Hornady 123 SST. I thought it was just my barrel but a buddy came by yesterday to bed his barrel and we checked his throat length and it is just as short as mine. Im having to load way short, around the 2.20 mark, to get them off the lands on my barrel. His is a Saturn Liberty SS 18" 5R barrel. Is this common for a Grendel? I have a hard time wrapping my head around the fact these chambers are cut to a spec that allows factory loads to get buried in the lands.

By the way, which bullet are you using for your handloads?

[Djgrendel]

Unfortunatly, there are still some shops making barrels that are not up to the task. Send it back. Plenty of good companies will make a barrel chambered correctly.

[rabiddawg]

Unfortunatly, there are still some shops making barrels that are not up to the task. Send it back. Plenty of good companies will make a barrel chambered correctly.

Good luck getting satern to do anything. They have never admitted making a mistake or telling a lie.

[beastep]

And I've spent some time in Garvin County. My grandfather ran a gas plant in Katie and I worked out of Velma for a few years.

Liberty's Grendel II and BCA's Grendel Type II may or may not be the same thing. I haven't seen confirmation of what BCA's chamber really is. At any rate, from looking at the reamer drawings, a Grendel II (Liberty) throat should be about a tenth of an inch or so deeper than in a SAAMI chamber.

Im trying to picture a gas plant in Katie but I cant. Im not far from there. I did some work out of the Velma plant when it was Texaco but that was years ago.

If I cant get this to shoot Ill just have someone with a Grendel reamer ream it for me. I would rather do that than send it back and wait on a new on thats cut the same way.

[beastep]

By the way, which bullet are you using for your handloads?

Hornady, 120 ELDM, 123 ELDM, 123 SST. I had to go down all the way to 2.19something to get the 120s off the lands. May not be completely off still.

[Crusty]

In my Satern Liberty 18" barrel at max mag length (2.296") 123gr ELD-Ms are still around .030" off the lands, but I found the best groups around 2.260".

BTW, COL measurements don't give you a uniform bullet seating depth in the case with ELD-Ms because the meplat varies so much but measurements to the ogive are consistent. The material forward of the ogive doesn't matter for firing anyway because it never touches the lands. I think the Hornady ogive caliper attachment is worth buying.

[Redraider]

I always saied I would never say this , but here goes.............SEARCH is your friend here!! I had a Liberty barrel on my rifle, but before I shot it this forum exploded with posts of Liberty being "short". My barrel would not let a round drop in, or out, so I had it reamed by a reputable Grendel shop..................I now have a Lilja, THE END!!

Liberty will FIX your chamber with another "new Design" of their own, which was their problem to start with, in my opinion, and I am NO expert on these.

All of these problems would have been non-existant if all of these barrel makers would have kept to the original design. Ego, maybe??

Redraider

[Crusty]

That's right Red. The first runs of Liberty barrels weren't reamed correctly (throat too short if I remember correctly) and to fix it they decided to make the throats straight and longer so everyone's ammo would at least fit.

[beastep]

In my Satern Liberty 18" barrel at max mag length (2.296") 123gr ELD-Ms are still around .030" off the lands, but I found the best groups around 2.260".

BTW, COL measurements don't give you a uniform bullet seating depth in the case with ELD-Ms because the meplat varies so much but measurements to the ogive are consistent. The material forward of the ogive doesn't matter for firing anyway because it never touches the lands. I think the Hornady ogive caliper attachment is worth buying.

I understand and agree with you. Right now I dont have the ogive caliper attachment but I will some day. So right now all I have to measure by is the OAL.

[Crusty]

That's what I did until I bought one of those caliper jaw attachments. Then I took a tray that I had loaded to the same COL and measured each at the ogive and I was surprised at the variance. Now I don't bother to measure the COL if they'll fit in the mag, but each one gets an ogive measurement as soon as it comes off of the press.

My loads are more consistent and I'm coming to believe that the volume of dead air space inside a loaded case makes a difference for consistent groups and so seating the bullets to the same depth in similar volume cases makes the dead air space consistent since I've got powder charges under control. My last step will be to measure and group my cases by internal volume.