22BR - 90 VLD and 80.5 from the same chamber

[APGE]

Hi Folks,

Given the long neck of the 22BR, if a rifle was throated to have a 90vld sitting just above the donut area, could you seat an 80.5 to the lands and still have enough shank in the case?

I know it's not easy with a 223 (been there, done that), but the neck on it is quite a lot shorter than the BR

Cheerio,
APGE

 

[Terry]

Yes

 

[Ned Ludd]

As Terry suggested, it is possible to seat the 80.5s in a rifle chambered for the 90s (at least in a .223 Rem case) as long as the freebore isn't excessive. For example, in a .223 Rem chambered with PTG's 223 Rem ISSF reamer that cuts 0.169" freebore, there is sufficient shank left in the neck when seating the 80.5s. I have loaded some dummy rounds with the 80.5s at ~0.020" off the lands and they are seated well out in the neck, but would work just fine.

However, it all depends on the specific chamber and how far out the neck the 90s are seated. IMO - the 0.169" freebore cut by the original PTG 223 Rem ISSF reamer is not sufficient for the 90s if they are seated ~.020" off the lands (or longer), which is where mine usually end up. In that scenario (i.e. 90s seated at ~.020" off the lands), a 0.169" freebore chamber will put the boattail/bearing surface junction just barely above the neck/shoulder junction. For that reason, I had a new reamer designed for the 90s with substantially longer freebore (0.220"). Although I have not checked it directly with dummy rounds, I suspect in a chamber cut with that reamer, seating the 80.5s might be problematic. I'd imagine there might only be about 0.050" worth of shank left in the neck with the 80.5s in that rifle. So as long as you don't "optimize" the freebore for the 90s all the way to the long end, it should work just fine with the 80.5s.

In order to clear the donut, the boattail/bearing surface junction of a seated 90 VLD should be somewhere well above the neck/shoulder, but probably doesn't need to be as far as halfway out the neck. So it might be close, again, depending on exactly how much freebore the chamber has. If you have both bullets in hand, setting up some dummy rounds might give you a better picture of how far out in the neck the 80.5s would be seated. Another option would be to select a different ~80 gr bullet that has a noticeably longer base-to-ogive dimension than the 80.5 Fullbore, such as Berger's 82 BTHP, or Hornady's 80 gr ELDM. I haven't personally tried either one, but have heard good things about both from people that have.

 

[dstoenner]

The Berger 82 .224 bullet has been discontinued.

David

 

[APGE]

As Terry suggested, it is possible to seat the 80.5s in a rifle chambered for the 90s (at least in a .223 Rem case) as long as the freebore isn't excessive. For example, in a .223 Rem chambered with PTG's 223 Rem ISSF reamer that cuts 0.169" freebore, there is sufficient shank left in the neck when seating the 80.5s. I have loaded some dummy rounds with the 80.5s at ~0.020" off the lands and they are seated well out in the neck, but would work just fine.

However, it all depends on the specific chamber and how far out the neck the 90s are seated. IMO - the 0.169" freebore cut by the original PTG 223 Rem ISSF reamer is not sufficient for the 90s if they are seated ~.020" off the lands (or longer), which is where mine usually end up. In that scenario (i.e. 90s seated at ~.020" off the lands), a 0.169" freebore chamber will put the boattail/bearing surface junction just barely above the neck/shoulder junction. For that reason, I had a new reamer designed for the 90s with substantially longer freebore (0.220"). Although I have not checked it directly with dummy rounds, I suspect in a chamber cut with that reamer, seating the 80.5s might be problematic. I'd imagine there might only be about 0.050" worth of shank left in the neck with the 80.5s in that rifle. So as long as you don't "optimize" the freebore for the 90s all the way to the long end, it should work just fine with the 80.5s.

In order to clear the donut, the boattail/bearing surface junction of a seated 90 VLD should be somewhere well above the neck/shoulder, but probably doesn't need to be as far as halfway out the neck. So it might be close, again, depending on exactly how much freebore the chamber has. If you have both bullets in hand, setting up some dummy rounds might give you a better picture of how far out in the neck the 80.5s would be seated. Another option would be to select a different ~80 gr bullet that has a noticeably longer base-to-ogive dimension than the 80.5 Fullbore, such as Berger's 82 BTHP, or Hornady's 80 gr ELDM. I haven't personally tried either one, but have heard good things about both from people that have.

Thank you for such a comprehensive and easy to follow answer!

If I had my smith throat the chamber so an 80.5 has 0.100" of shank in the neck, do you think I would be able to keep 90s above the donut area still, or do I need less of the 80.5 in the case still?

 

[Ned Ludd]

0.100" is just under half the neck length on a .223 Rem case, and just under half the bullet diameter. I don't have the exact specs in front of me for the 22BR case neck. Nonetheless, it's possible you might be able to get away with slightly less than 0.100" shank of the 80.5 in the neck, but that's largely personal preference and I wouldn't want to go too much under that.

Whether that will put you above the donut with a 90 VLD can be calculated/estimated from the distance between the bottom edge of the bearing surface (i.e. top of the boattail) to the ogive for the 2 bullets. If my calculations using dimensions from Bryan Litz' book ["Ballistic Performance of Rifle Bullets", 2nd Ed., 2015] are correct, the value for the 80.5 is approximately 0.404", whereas the value for the 90 VLD is approximately 0.426". In other words, these are the two estimated bullet lengths for the region between the boattail/bearing surface junction and the point that first contacts the lands. As you can see, they're not very different, even though other dimensions between the two such as OAL and nose length are quite different.

The bottom line is that these are book values and only useful as a crude estimate. Actual Lot-to-Lot length variance will even change those numbers to some degree. As I suggested before, this is an example where it is probably much easier and likely more reliable to simply load up some dummy rounds with the two bullets than trying to obtain a definitive answer using estimated bullet lengths and calculations. I think you will likely be able to achieve your goal, but having dummy rounds in hand that you can actually measure would be beneficial for selecting the optimal freebore length to use both.

 

[Evan]

You could buy a box of ether 80.5 or 90, whichever you're more interested in starting with, then post up asking if someone wants to trade a few bullets: you send them 3 90s and they send you 3 80.5, as an example.

 

[JAlfred]

If you want a few 80.5s to play with, shoot me an IM and I'll get you some in the mail this weekend.