6.5 PRC Reamer & Seating Depth Considerations

orkan

Primal Rights, Inc.
Banned !
Minuteman
  • Oct 27, 2008
    4,268
    4,009
    South Dakota, USA
    www.primalrights.com
    Yesterday I had a good talk with Travis Stevens of TS Customs. He called because he discovered an interesting thing regarding the PRC and wanted to talk it through. Here are the facts.

    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/1677/6-5prc-lone-peak-fuzion-kmw-sentinel-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.
     
    Considering that, would you think that if you ran the 147 ELDM in an "old" chamber at, say 10 thou off the lands, that the boat tail would be below the neck/shoulder junction of the brass?
     
    orkan- thanks for the heads up on this; while I myself am not currently planning on building a rifle with this chambering, this is the sort of information that could save some headaches down the road for those who do.
     
    The guy chambering my buddy and my barrels ordered a reamer from Manson. He said Manson had worked with horned on the project before it went public and their reamer had been the proprietary reamer for Hornady until they recently released it to sell to the public. Not sure what the specs are on free bore but should be an interesting project for sure. I'll have to give him a call to see if he knows the free bore spec. Thanks for the heads up.
     
    You're welcome shoot4fun.

    I've been contacted by at least 3 different people, all claiming to have secret squirrel information and that they "worked with hornady" on this before it came out. I don't really care who did what... I just know that this kind of thing can ruin a guy's build if not thought out. It comes down to making a choice between short action mag length with jump or no jump. After that a guy can choose to simply go with a mid or long action and custom freebore and boom problem solved. At least the info is here and we can have a discussion about it so everyone knows. :)
     
    You're welcome shoot4fun.

    I've been contacted by at least 3 different people, all claiming to have secret squirrel information and that they "worked with hornady" on this before it came out. I don't really care who did what... I just know that this kind of thing can ruin a guy's build if not thought out. It comes down to making a choice between short action mag length with jump or no jump. After that a guy can choose to simply go with a mid or long action and custom freebore and boom problem solved. At least the info is here and we can have a discussion about it so everyone knows. :)

    Yeah, thanks a lot for putting up this info. I'm planning a long range build on an existing short action of mine and am debating between the PRC and the SAUM 4S, was leaning towards the PRC for what I figure would be easier to source brass but was also planning on running 147s. Might go with the 4S instead now.
     
    Yesterday I had a good talk with Travis Stevens of TS Customs. He called because he discovered an interesting thing regarding the PRC and wanted to talk it through. Here are the facts.

    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/1677/6-5prc-lone-peak-fuzion-kmw-sentinel-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.



    Had the same experience with PTG reamer. Factory 147 ELD-M ammo at 2.95 coal was getting jammed .012. My Smith used his 6.5 throater to give me some more freebore. After that was extremely impressed how well that factory ammo shot. Fell in love with 6.5 PRC too, my all time favorite
     
    I am building a 6.5 PRC using a Stiller medium length action, Brux 24' barrel and McMillan stock. With that in mind do I understand that I will be fine with the new Hornady spec freebore of .1882? I more than likely will be loading 140 Berger Hybrids but may try the Hornady 143 ELDX. The medium action and blind mag allows longer length than a standard mag so the bullet won't protrude into the case.
     
    I am building a 6.5 PRC using a Stiller medium length action, Brux 24' barrel and McMillan stock. With that in mind do I understand that I will be fine with the new Hornady spec freebore of .1882? I more than likely will be loading 140 Berger Hybrids but may try the Hornady 143 ELDX. The medium action and blind mag allows longer length than a standard mag so the bullet won't protrude into the case.

    Have you received your Stiller medium predator yet?
     
    • Like
    Reactions: Lynn313
    I am building a 6.5 PRC using a Stiller medium length action, Brux 24' barrel and McMillan stock. With that in mind do I understand that I will be fine with the new Hornady spec freebore of .1882? I more than likely will be loading 140 Berger Hybrids but may try the Hornady 143 ELDX. The medium action and blind mag allows longer length than a standard mag so the bullet won't protrude into the case.

    Should be fine if your blind mag will let you load long. I gave a loaded round to my gunsmith (147's loaded just above the donut area) and the 130 freebore worked fine. 140 Nosler RDF's (and presumably hybrids) work with that freebore as well.
     
    • Like
    Reactions: jheard50
    So who dropped the ball on the 6.5 Prc because I had my first custom rifle build with this and to be honest I am a little upset . Also if it wasn’t for you guys I would still be talking to my smith till I was blue in the face trying to explain this he either didn’t believe me or didn’t want to believe me . Thank guys I appreciate it thanks
     
    I got my PRC and am happy. Jonathon at Fine Firearms in La Mesa CA built it for me. 24" #3 fluted Brux barrel, Stiller Predator (med action), oversize stiller recoil lug, Shilen trigger at 3 lbs, blind Stiller magazine, McMillan Hunter stock , Woody finish, action glass bedded, Graphite black Cerakote topped with pinned Talley rings, and a Leupold VX5 3-15x44 scope. Used the 0.1883 freebore. First shot was sighting in then next were 10 shot group using factory Hornady Precision Hunter with 143 ELDX. Going to reload with Berger 140 Hunter Elites using H1000
     

    Attachments

    • 6.5 prc.jpg
      6.5 prc.jpg
      213.3 KB · Views: 228
    • PRC first shots.JPG
      PRC first shots.JPG
      230.5 KB · Views: 223
    I still think the PRC would be the better choice... but you just need the right reamer.

    Just saw this @ would appreciate feedback. My Stiller Predator medium w/ Stiller BDL floorplate is at smith shop. Not chambered yet. My concern on freebore is can I think I will have to freebore for the Hornady or Berger’s. I’m thinking it won’t work right with both. 2nd question is have you heard of a match reamer for 6.5 PRC that will tighten neck tolerances similar to what I did with my 300 WM? Appreciate your time and help.
     
    I got my PRC and am happy. Jonathon at Fine Firearms in La Mesa CA built it for me. 24" #3 fluted Brux barrel, Stiller Predator (med action), oversize stiller recoil lug, Shilen trigger at 3 lbs, blind Stiller magazine, McMillan Hunter stock , Woody finish, action glass bedded, Graphite black Cerakote topped with pinned Talley rings, and a Leupold VX5 3-15x44 scope. Used the 0.1883 freebore. First shot was sighting in then next were 10 shot group using factory Hornady Precision Hunter with 143 ELDX. Going to reload with Berger 140 Hunter Elites using H1000

    I’m building with a Stiller Predator medium action. Are you able to load to the lands with the 140 Berger’s & how much bearing area is in neck if so? Thanks, Lynn
     
    Here are some quick and dirty measurements I did to see where various bullets line up. Mine is speced as a SAAMI chamber (.188 freebore). These were measured by hand, and with randomly selected bullets that I had, so the measurements are probably +/- a few thousands and my chamber/bullets may not match yours, but it will give you an idea how close/far various bullets are from the lands.
    BulletOAL to JamOAL .050 jumpOAL .020 jumpJump for mag
    length 2.98
    JLK VLD 140
    3.051​
    3.001​
    3.031​
    0.071​
    Flatline 122
    3.042​
    2.992​
    3.022​
    0.062​
    Horn 140 ELD
    2.949​
    2.899​
    2.929​
    0.000​
    Barnes 127 LRX
    2.950​
    2.900​
    2.930​
    0.000​
    Sierra 150 MK
    3.068​
    3.018​
    3.048​
    0.088​
    Berger 140 Hybrid
    3.031​
    2.981​
    3.011​
    0.051​
    Berger 140 VLD
    2.975​
    2.925​
    2.955​
    0.000​
    Horn 147 ELD
    2.994​
    2.944​
    2.974​
    0.014​
     
    Thanks, nice info for someone like me waiting on build to view. Appreciate the effort! Looks like if I go with spec freebore of 188 I can load Hornady ‘s & Berger’s to the lands. I look a SAMMI specs sheet. It looks like neck in chamber is .299 (could be wrong) GAP is using a .296 neck
     
    Thought I'd chime in.
    I have confirmed with Jeremy Riddle at GAP that they are currently using the .130" reamer for all their 6.5 PRC builds.
    He said the 147 grain Hornady ELD-M factory ammo just touches the lands. Confirmed easy bolt closure and easy bolt lift with no pressure signs after firing. OAL for this ammo is roughly 2.955".
     
    Considering that, would you think that if you ran the 147 ELDM in an "old" chamber at, say 10 thou off the lands, that the boat tail would be below the neck/shoulder junction of the brass?
    I called Hornady for measurements. BT = .150 thou. Taking the overall measurements of the case and bullet you can back calculate Hornady factory ammo has ~ 88 thou of bearing area buried below the neck/shoulder junction. After looking at measurements I canceled my build on a s/a and am building on a medium action.
     
    Just saw this @ would appreciate feedback. My Stiller Predator medium w/ Stiller BDL floorplate is at smith shop. Not chambered yet. My concern on freebore is can I think I will have to freebore for the Hornady or Berger’s. I’m thinking it won’t work right with both. 2nd question is have you heard of a match reamer for 6.5 PRC that will tighten neck tolerances similar to what I did with my 300 WM? Appreciate your time and help.

    aalf's reamer is running a no turn neck and .200" of freebore. He runs a long action.

    Thought I'd chime in.
    I have confirmed with Jeremy Riddle at GAP that they are currently using the .130" reamer for all their 6.5 PRC builds.
    He said the 147 grain Hornady ELD-M factory ammo just touches the lands. Confirmed easy bolt closure and easy bolt lift with no pressure signs after firing. OAL for this ammo is roughly 2.955".

    My Havak PH1 6.5 PRC does not like 147ELDM's in the lands or anywhere near them. It's my impression this experience isn't uncommon and that these bullets like lots of jump. This report (copied above) appears as a bit of an enigma. George Gardner's 6.5 SAUM, 4S, 6.5 PRC Forum on FB is littered with scads of reports from folks loading 147ELDMs with lots of jump (+.050").

    Regarding Bergers:
    With a .188 freebore throat, getting Bergers into or near the lands doesn't leave much bearing surface in the case neck. Adding to Acourvil's chart above in a my .188 free-bore throat COAL's =
    147 ELDM 3.001 (vs. Acourvil's 2.994")
    140 VLDH 3.006
    140 EH 3.075

    While these are rough figures, they illustrate the nuanced bargaining one must do when deciding on action length, mag length, bullet (OAL vs. bearing surface vs. seating personality), and reamer and throat dimensions for the 6.5 PRC.

    The easy button seams to be a SA, M5 binder-less, .188 free-bore SAAMI spec JGS reamer, and ELDM/X's loaded with plenty of jump.
     
    aalf's reamer is running a no turn neck and .200" of freebore. He runs a long action.



    My Havak PH1 6.5 PRC does not like 147ELDM's in the lands or anywhere near them. It's my impression this experience isn't uncommon and that these bullets like lots of jump. This report (copied above) appears as a bit of an enigma. George Gardner's 6.5 SAUM, 4S, 6.5 PRC Forum on FB is littered with scads of reports from folks loading 147ELDMs with lots of jump (+.050").

    Regarding Bergers:
    With a .188 freebore throat, getting Bergers into or near the lands doesn't leave much bearing surface in the case neck. Adding to Acourvil's chart above in a my .188 free-bore throat COAL's =
    147 ELDM 3.001 (vs. Acourvil's 2.994")
    140 VLDH 3.006
    140 EH 3.075

    While these are rough figures, they illustrate the nuanced bargaining one must do when deciding on action length, mag length, bullet (OAL vs. bearing surface vs. seating personality), and reamer and throat dimensions for the 6.5 PRC.

    The easy button seams to be a SA, M5 binder-less, .188 free-bore SAAMI spec JGS reamer, and ELDM/X's loaded with plenty of jump.

    If people are posting they are using factory Hornady 147g ELD-M Match ammo and they are +.050 off the lands, their rifles must have been built with the new .188" freebore reamer. That doesn't mean 147g ELD-M handloads can't be seated deeper than the Hornady factory match ammo, but I know for a fact GAP is currently using the .130" FB reamer for all their 6.5 PRC builds and this puts the Hornady 147g ELD-M Match ammo at the lands.

    I made a point to contact Ken Lin at GAP about the reamer they use and I received this reply:

    .130" FB is current GAP standard. please let me know if you have any other questions.
    --
    Ken Lin
    GA Precision
    Professional Quality Rifles and Equipment
    Mailing and Shipping Address:
    1141 Swift Street
    North Kansas City, MO 64116
    Office: (816) 221 - 1844 ext. 1
    Fax: (816) 421 - 4160
    Email: [email protected]
    Online at GAPrecision.net
     
    As an additional data point, I just finished load development with the 147 ELDs and settled on a .035 jump. In my rifle, it was slightly better than .050, which was better than .020. This is a load with H1000, not sure if it would be the same for RL26, which I intend to try if it ever becomes available.
     
    As an additional data point, I just finished load development with the 147 ELDs and settled on a .035 jump. In my rifle, it was slightly better than .050, which was better than .020. This is a load with H1000, not sure if it would be the same for RL26, which I intend to try if it ever becomes available.

    AC, How fast are you running, on how much H1000 and out of what lengths bbl? .130 or .188 throat?

    I ran 147 ELD-M’s on 57.8gr of H1000 seated from the the lands to 0.060 off today. Velocity ranged from 2940 to 2989 in a 24” .188 throat, Seekins Havak PH1. A couple variations showed promise, but need more development.
     
    I'm at 2980fps in a 26" Bartlein barrel, SAAMI .188 freebore, ADG brass, 58.3 H1000. No pressure signs up to 58.5, but I didn't go any higher than that because I think 3000fps is probably the max you can get out of H1000 and I had a nice flat area from 58.1 to 58.4.

    The .035 jump gives me a 2.96 OAL. I did not try jamming because it would be longer than my mag length, and generally I prefer not to jam anyway.

    The volume of once fired ADG is very close to the volume of once fired Hornady, 68.3gn v. 68.6gn.

    Using Hornady factory 147 ammo as a test, my barrel picked up about 90fps between virgin and 200 rounds (from 2851 to 2941). It's possible some of that was temp related (early shooting in the 40s/50s, later shooting in the 70s), but I don't have any way to know for sure.
     
    Last edited:
    I'm at 2980fps in a 26" Bartlein barrel, SAAMI .188 freebore, ADG brass, 58.3 H4350. No pressure signs up to 58.5, but I didn't go any higher than that because I think 3000fps is probably the max you can get out of H1000 and I had a nice flat area from 58.1 to 58.4.

    The .035 jump gives me a 2.96 OAL. I did not try jamming because it would be longer than my mag length, and generally I prefer not to jam anyway.

    The volume of once fired ADG is very close to the volume of once fired Hornady, 68.3gn v. 68.6gn.

    Using Hornady factory 147 ammo as a test, my barrel picked up about 90fps between virgin and 200 rounds (from 2851 to 2941). It's possible some of that was temp related (early shooting in the 40s/50s, later shooting in the 70s), but I don't have any way to know for sure.

    AC, Thanks for the data points. Did you mean to mention H4350?

    In a 24” Rock 1:8 with .188 freebore:
    I see slight pressure (very light swipe) at 58.5gr. H1000 (ambient ~60°F) yielding average velocity of 2998; ES=7. Then at 59 - 59.2 all signs of pressure are gone, but seating to mag length compresses load and ES grows to 24.

    I shot 57.8gr of H1000 under 147 ELDM's at five seating depths at (.025; .0265; .035; 045; .055)

    Of those 0.035 off the lands produced the smallest group at an avg. velocity of 2962; ES=9 (it was windy as hell)

    I’m going to retest this load and might also try a few more with slightly smaller charges of H1000 and reduced jump.

    Then I might try Winchester 780 Supreme, and RL26 and maybe 8133.
     
    The reference to H4350 was a brain fart, should have said H1000 in both places.

    Interesting that we both ended up at .035 jump.

    I’m going to try RL26 t some point, but probably not until there is enough around that I could use it regularly.
     
    Interesting that we both ended up at .035 jump

    It is. I’m not ready to trust my groups without some more testing. It was windy as hell yesterday. I also need to run a few sets seated long, say .015; .005; -.001.

    My .025 and .0285 groups showed promise too. I round-robin shots, shooting one of each load variant, then repeating the same sequence—all with a luke warm barrel. Each load variant gets its own aiming point.

    Conditions yesterday were very windy and the wind changed directions several times. It was a good day to get velocities and season a barrel. :).
     
    Hello guys I need a little guidance here is my reamer spec sheet from smith can someone point out please the free bore I’m not seeing it on this sheet or I’m blind or possibly a idiot too thanks
     

    Attachments

    • 2DBD9BE2-830D-41BB-8A09-2A29EA8B6A3C.jpeg
      2DBD9BE2-830D-41BB-8A09-2A29EA8B6A3C.jpeg
      459.6 KB · Views: 513
    Hello guys I need a little guidance here is my reamer spec sheet from smith can someone point out please the free bore I’m not seeing it on this sheet or I’m blind or possibly a idiot too thanks
    I also would like to learn how find out the freebore........messing with some numbers I may have gotten the number but idk if it’s right, sounds right anyway: I took the 2nd pictures 2.2447 number and subtracted that from the same pictures 2.0568 number and ended up with .1879. That is the SAAMI spec so I think I did it right?
     
    Yesterday I had a good talk with Travis Stevens of TS Customs. He called because he discovered an interesting thing regarding the PRC and wanted to talk it through. Here are the facts.

    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/1677/6-5prc-lone-peak-fuzion-kmw-sentinel-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.
    Thank you.
     
    Yes my first chambering I could not get bolt to close with factory round rented a new reamer which to my knowledge is the .188 free bore we will see what happens now I would like to know who at hornady dropped the ball on the specs and if they are going to do anything for the guys that got the wrong speced reamer I started this build a when hornady first come out with this caliber and just finally got to try it out a few weeks ago after having it to 2 different Smith and slot of dollars later
     
    Seems to be a lot of confusion on the Freebore, or maybe I’m just confused. I’m wanting to run 140 hybrids in a short action. Seems like the .130 freebore is best for my application and handloaders in general?