100fps
- Thread starter sako2
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reynolds357
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I would step powder up until I got my 100 fps back or saw a pressure sign.
stagpanther
New member
I don't shoot the 6.5 PRC--but I do shoot the 25 PRC which is necked down from the 6.5. I personally think venturing into slow-burning fine ball magnum powders in the PRC at high capacity volumes and lighting them off with magnum primers is asking for trouble. I don't know about your barrel, but mine is filthy with fouling after firing high capacity magnum loads. Your loads are past where I would go even if you're not seeing pressure signs. I've taken apart 6.5 PRC cartridges from 3 different manufacturers and they all used a stick powder which while I don't know what they actually are I'm willing to bet they are faster non-magnum powders. I've had primer pockets get stretched after just 2 shootings with magnum loads not as warm as your top loads.
The PRC brass itself is tricky stuff to work in my experience and I found that I have to pay very close attention to just how much shoulder movement there is between unfired and fired cases, I keep those tolerances at no more than .003, preferably closer to .002. Bumping the shoulder back is tricky with the PRC, it seems to have a weak spot at the junction of the base of the shoulder and main body and can form a ring if you're not careful, which in turn can stop cartridge from headspacing correctly on the shoulder.
Just my personal experience and opinions.
The PRC brass itself is tricky stuff to work in my experience and I found that I have to pay very close attention to just how much shoulder movement there is between unfired and fired cases, I keep those tolerances at no more than .003, preferably closer to .002. Bumping the shoulder back is tricky with the PRC, it seems to have a weak spot at the junction of the base of the shoulder and main body and can form a ring if you're not careful, which in turn can stop cartridge from headspacing correctly on the shoulder.
Just my personal experience and opinions.
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stagpanther
New member
BTW--TX Ammo has Norma match ammo for $36 dollars a box--I just bought a bunch just for the brass.
That's 17% difference in case volume. Are you sure? In the original post, you said the case difference was 1 grain H2O, not 10.
-TL
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reynolds357
New member
With the powder advancements, shape now means nothing.
stagpanther
New member
you mean dimensions of the case? I've tried several slow-burning spherical magnum powders and found they do not perform especially well in my 25 PRC compared to faster powders like 4350 and 4955. While not strictly shape dependent--the necking down to 257 does make it a serious overbore.
reynolds357
New member
I mean shape of powder. Ball vs extruded. I do agree about burn rate. The 6.5 Prc is not overbore enough for the slowest powders.
That sounds more reasonable. That's 1.4%, half of percentage difference in MV.Tangolima it was 69gn h20 in the hornady and 70 in the norma. My mistake.
I noticed similar thing in my 5.56 load. The variation in case volume, even same brand and same date code, can easily change the MV by 75fps. Sounds a lot in fps, but only a couple of percent around the mean. It has become normal to me. In order to reduce the variation, I started sorting brass by weight. It helps.
The other often overlooked factor is temperature. Each degree F can cause as much as 0.1% in MV. That's 30fps when temperature changes from 70F to 80F.
In order to compensate for the loss of speed, the charge will need to be adjusted roughly by the same percentage. Be careful when doing it. Chasing speed could be dicey.
-TL
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stagpanther
New member
You mean modern formulations ensure better ignition performance? I've loaded retumbo, magnum, magpro and one or two other slow burners and in my barrel just wasn't getting good results--OK, but not the laser sharp groups the newer 25's are fast gaining a reputation for. The blackjack bullets are just an empty hole in my wallet, I never received them, but I've had pretty good results with 120 gr PVA senecas and berger's 133 hybrids using faster extruded powders. With a 90 some percent case fill using 4955 I'm getting 3250 fps with the 120's and a clean burn in my barrel, with the 133 hybrids I'm getting just over 3000 fps using 4350 also clean and both loads are under max pressure (I also try to stay with a "buffer" margin under the max pressure in the theory that will hopefully help prolong the barrel life some). I haven't loaded the 6.5 PRC, but my chamber will take the senecas seated past 3" COL. Along with the price of everything else going up--so too are the prices of barrels. 500 to 700+ dollars is starting to push barrels out from "consumables" to "luxuries" since my income has moved in a reverse direction from inflation in the past few years.
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1gr over 62gr is not quite 3%. I suggest not to fixate on the speed. It shoots well. That's what counts.
-TL
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reynolds357
New member
Modern formulations have allowed Ball powders to burn as slow as extruded powders.You mean modern formulations ensure better ignition performance? I've loaded retumbo, magnum, magpro and one or two other slow burners and in my barrel just wasn't getting good results--OK, but not the laser sharp groups the newer 25's are fast gaining a reputation for. The blackjack bullets are just an empty hole in my wallet, I never received them, but I've had pretty good results with 120 gr PVA senecas and berger's 133 hybrids using faster extruded powders. With a 90 some percent case fill using 4955 I'm getting 3250 fps with the 120's and a clean burn in my barrel, with the 133 hybrids I'm getting just over 3000 fps using 4350 also clean and both loads are under max pressure (I also try to stay with a "buffer" margin under the max pressure in the theory that will hopefully help prolong the barrel life some). I haven't loaded the 6.5 PRC, but my chamber will take the senecas seated past 3" COL. Along with the price of everything else going up--so too are the prices of barrels. 500 to 700+ dollars is starting to push barrels out from "consumables" to "luxuries" since my income has moved in a reverse direction from inflation in the past few years.
I don't have a 6.5PRC, but I have been getting stellar results from Staball 6.5 in my 6 5 x 284 with 130 Berger VLD hunting.