alf
Silver $$ Contributor
So last fall I got the itch to try the new Hornady 6.5 PRC cartridge. I already had the platform, so I really only needed a reamer and a barrel.
After quite a bit of research, I gathered up some details:
6.5 creedmoor: 52-53 gr case capacity
6.5 SLR: 55-56 gr
6.5 PRC: 66-67 gr
6.5 SAUM: 70-71 gr
The PRC has 25% more capacity than a creedmoor, and 5-6% less than a SAUM. In quickload, holding pressure constant at 57k psi in a 26" barrel with 140 hybrids, a 6.5 SAUM (H1000) is about 30-40 fps faster than a 6.5 PRC (H1000), and the PRC is 220 fps faster than a 6.5 creedmoor (H4350).
Then I found this PSA on throating & overall lengths:
The original reamer spec that most folks have been using to chamber PRC barrels is likely not going to natively work with the recently launched hornady factory ammo. This came to light due to the recently released Hornady reamer spec which JGS has as of just a few days ago. On that print, the freebore is indicated as .1882". The reamer that Travis presently has matches the spec PT&G had on file for the PRC which puts the freebore at .1302".
I've worked with chambers on that original PT&G reamer as seen here: https://forums.gunhive.com/topic/167...and-ts-customs
You'll notice in that write-up I was using a berger 140 hybrid and ended up ten thousandths off the lands with an OAL of 2.940". Hornady factory ammo is measuring 2.945 for both the 143ELDX and 147ELDM. Based on tip to ogive measurements, this would put hornady factory ammo jammed into the lands on the original PT&G reamer spec about ten thousandths. On the new reamer with the .1882 freebore, you'd be looking at approx 50 thousandths jump. Tip to ogive measurement on a 140 berger hybrid is about 20 thousandths longer than a 147 hornady... so you can plainly see what this differing spec can mean for those looking to shoot factory ammo in their "old" chambers.
Some obvious things about that situation are that if you have an "old" PRC chamber, factory ammo will be jammed... while if you have a "new" PRC chamber, you'll never be able to get closer than 40 thousandths or so from the lands in max strapless AICS format magazines like Accuratemag.
I do not know where the PT&G original spec came from, but it's clear that the hornady spec reamer print from JGS would indicate the future direction of the design and this is further supported by the fact their current factory ammo will certainly work fine in their new spec. It does present a dilemma for handloaders or custom builders however. On one spec you can run a short freebore and be able to approach the lands at mag length. On the other spec you'd never be able to approach the lands in a short action with the longest mags available for it. A mid or long action with associated mags would be the only way to get into the lands with the "new" spec.
Both Travis and I felt it prudent to do a little PSA about this situation, as it's likely there are more than a couple rifles out there with short PRC chambers that will result in factory ammo being jammed to the tune of 10 thousandths or better.
After quite a bit of research, I gathered up some details:
6.5 creedmoor: 52-53 gr case capacity
6.5 SLR: 55-56 gr
6.5 PRC: 66-67 gr
6.5 SAUM: 70-71 gr
The PRC has 25% more capacity than a creedmoor, and 5-6% less than a SAUM. In quickload, holding pressure constant at 57k psi in a 26" barrel with 140 hybrids, a 6.5 SAUM (H1000) is about 30-40 fps faster than a 6.5 PRC (H1000), and the PRC is 220 fps faster than a 6.5 creedmoor (H4350).
Then I found this PSA on throating & overall lengths:
The original reamer spec that most folks have been using to chamber PRC barrels is likely not going to natively work with the recently launched hornady factory ammo. This came to light due to the recently released Hornady reamer spec which JGS has as of just a few days ago. On that print, the freebore is indicated as .1882". The reamer that Travis presently has matches the spec PT&G had on file for the PRC which puts the freebore at .1302".
I've worked with chambers on that original PT&G reamer as seen here: https://forums.gunhive.com/topic/167...and-ts-customs
You'll notice in that write-up I was using a berger 140 hybrid and ended up ten thousandths off the lands with an OAL of 2.940". Hornady factory ammo is measuring 2.945 for both the 143ELDX and 147ELDM. Based on tip to ogive measurements, this would put hornady factory ammo jammed into the lands on the original PT&G reamer spec about ten thousandths. On the new reamer with the .1882 freebore, you'd be looking at approx 50 thousandths jump. Tip to ogive measurement on a 140 berger hybrid is about 20 thousandths longer than a 147 hornady... so you can plainly see what this differing spec can mean for those looking to shoot factory ammo in their "old" chambers.
Some obvious things about that situation are that if you have an "old" PRC chamber, factory ammo will be jammed... while if you have a "new" PRC chamber, you'll never be able to get closer than 40 thousandths or so from the lands in max strapless AICS format magazines like Accuratemag.
I do not know where the PT&G original spec came from, but it's clear that the hornady spec reamer print from JGS would indicate the future direction of the design and this is further supported by the fact their current factory ammo will certainly work fine in their new spec. It does present a dilemma for handloaders or custom builders however. On one spec you can run a short freebore and be able to approach the lands at mag length. On the other spec you'd never be able to approach the lands in a short action with the longest mags available for it. A mid or long action with associated mags would be the only way to get into the lands with the "new" spec.
Both Travis and I felt it prudent to do a little PSA about this situation, as it's likely there are more than a couple rifles out there with short PRC chambers that will result in factory ammo being jammed to the tune of 10 thousandths or better.
