BrentM
Well-Known Member
I run a 308 no binder plate at 2.950. It's weird but every bullet I've shot out of that rifle is 2.950 coal and all shoot exceptionally well.
6.5 PRC 156 load development
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With the 156's I'm using 60 grains of H1000, no pressure signs and shoots very accurate out to 1000 yards and still consistent to a mile
BrentM
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H1000 was good when i tested it too. I run 2900-2915 in a 22" so if you're anywhere around that area I'd guess you are fine. H1000 gave me 2880 and low sd btw
Put your fired cases back into chamber and close the bolt. If you're getting little resistance and bolt closes fairly easily, you're fine. Over expansion from high psi will usually not let you close the bolt on fired cases, without much resistance anyway. This is a test I use to determine the safe psi in my cartridge. Now it's important to only be bumped 2-3k when sizing and using this method. Too much sizing will hide psi signs as well, as the cases expansion to chamber is absorbing some the psi.
False ejector marks can show up as well from too much sizing. Or from a rough ejector plunger.
Sending156s
Well-Known Member
I'm shooting 3100 + in a GAP 6.5 PRC built on an XM action. OAL = 3.07, 156 EOL, RL26, ADG brass, Fed GM210M. Have to wait to get home to check powder gr. My home range only goes to 300 yards. At 300 my thumbnail will cover group. All I shoot are 156s .& some 153.5 Berger's
I think the OAL may play a bigger part than I think when it comes to this bullet and pressure. Maybe not though. I see a lot of people using ADG brass to get speed consistently, is that a bigger issue than I think/ I have ADG brass for me 300 PRC.
vancewalker007
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I'm getting 3040fps from a 26in barrel and 58.2gr of H1000. It's been my load for 2 hunting seasons. The only other bullet I'm shooting is the 127 LRX to have a mono for Africa. I tried the 140 EH, 142ABLR, 143 ELDX, and 147 ELDM. They all shot pretty good but the 156 shot super and it's a killer.
Sending156s
Well-Known Member
H1000 is great & stable. I switched back to it from RL26 with my 300 WM. I haven't killed anything with my 156s, but I've heard good reports. Thanks for sharing. I'm also shooting through a 26" barrel.....Bartlein.
I think with the 6.5 PRC it is not a true SA cartridge. When you build it on an XM action you can load efficiently. Do the math on Hornady commercial 6.5 PRC ammo and see almost 80 thou of bullet bearing area buried beneath the case neck/shoulder junction.
vancewalker007
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I agree on the internal ballistics issue. I think with these small cases it has a bigger impact on top end performance. I noticed a difference in the 300 WSMs I used to load for. When we built the 2 6.5 PRCs my father and I have we used the XM lengths and we had the 147 ELDMs set up to put their base just at the neck shoulder junction to maximize the internal ballistics possibilities. I am able to load my 156s at around 3.1in with them 15 off. I get fairly high velocities from the other bullets I've tried. For example I get 3170fps from 8133 and the 127LRX. I could likely get 3200+ with RL26. I just cannot depend on getting that powder.
Sending156s
Well-Known Member
What you are saying matches what I experience also. On my Stiller XM action the Bartlein bbl is custom throated for the 147 elm which loads out to 3.07 with the Berger. The base is at neck/shoulder junction & I'm kissing lands. I've hit 3220+ with rl26, but had heavy bolt lift w/ slight ejector mark so I backed down & shooting 3100+ with no pressure.
my 6.5 PRC built on a mag fed defiance Xm action is back at GAP getting another barrel put on. It is being custom throated off some dummy rounds built with ADG brass & 156 EOLs. I have 600 Lapua on backorder. Hopefully they will come in one day.
I do see the same vel with my 6.5 PRC built on an Xm action that other people usually can't get with a saum on a SA . Of course the 26" Bartlein helps!
BrentM
Well-Known Member
I am not agreement with you guys on the internal ballistics side of this yet. I have not been able to prove that adding a minute amount of internal volume to the case via moving the bullet .050 further out is worth any velocity change worth taking note of. Where things become more abrupt is if you are actually compressing the charge and then you can see gains and lower pressure for sure. I don't see anyone running 60 grains or less at 2.920-3.00 coal compressing any of the popular powders. As for speed I ran a 130 berger in my 22" barrel at 3150 at .5 grains under max. Max load, slight ejector mark, showed 3200. I ran this bullet at 2.950 COAL just like all the others. Just not convinced a long or medium action is gaining anything. A 2.80" box or mag would not be ideal but many of the internal oem mags seem to run much longer than 2.80.
vancewalker007
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That's ok you can disagree. This stuff is all anecdotal anyway and the difference in performance will vary rifle to rifle and cartridge to cartridge. All I can tell you is I did notice a difference in 3 300 WSMs I loaded for a few years ago and I wasn't looking for it, it just showed up. Two of rifles were SAAMI spec'd chambers the third was a custom chamber set up to shoot long .30 cal bullets. Now of course the barrels were not from the same company and the actions were all different. The barrels were all 24 inches, not that matters as I was looking more at pressure signs. I was using the same components in all 3 rifles.
The SAAMI rifles were a Sako A7 and a Winchester M70. The custom barrel was on a Kimber Montana action. When shooting say a Berger 190 VLD the SAAMI rifles had to be seated much deeper than the custom rifle to fit in the mags and shoot good. In the custom the 190s would end up with the bullet base near the neck/shoulder junction, the SAAMI chambers required the bullet to be around a .25in into the powder column. When shooting powder ladders I noticed I could always get almost an extra grain of powder into the custom chamber before pressuring out. I didn't completely understand the phenomenon until the read this article on Berger's site.
Effects of Cartridge Over All Length (COAL) and Cartridge Base To Ogive (CBTO) - Part 1
Many shooters are not aware of the dramatic effects that bullet seating depth can have on the pressure and velocity generated by a rifle cartridge. COAL is also a variable that can be used to fine tune accuracy. It’s also an important consideration for rifles that need to feed rounds through a...
bergerbullets.com
So, when I built my PRC I wanted to take as much advantage of the case space as possible and to do that I needed a longer action to put the bullet base where I wanted. I wish I would have had the 156 EOL when I had it built but it wasn't. I guess I could have used a 700 Long action and achieved the same effect. I don't have a SAAMI 6.5 PRC to compare to with the same loads so I cannot say how much difference there would be with this cartridge.
BrentM
Well-Known Member
OK, I see the point when discussing .250 thou vs a .050. For example if you stuff that bullet to a 2.80 vs 3.0 that a big difference, especially if you are looking at 95% fill rate already. I just don't see, in my testing as well, that shoving that bullet to the lands at 3.0 vs running it at mag of 2.95 made any noticeable difference. The volume being displaced inside the case is relatively small.
