6.5-7 PRC vs 6.5-300 PRC
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Rocketeer77
Well-Known Member
Wouldn't a heavier projectile used in a shorter barrel be the ideal. Also what's the benefits of a shorter barrel, that's genuine benefits for a practical hunting rifle. We run 24" and 22" barrels on all our hunting rifles most with suppressors and they're not an issue. Some hunters here who're hunting in heavy bush use 308's with 18" barrels and a maximum range of say 200MI've been kicking around ideas for my next build and I wanted to build a 6.5-7 PRC with a shorter barrel, around 20-22", and shoot Berger 156 EOLs. Then I was thinking, why not add some more displacement and do a 6.5 300 PRC? I already know that the more powder you burn down a barrel the shorter it's life will be so there is no need to rehash that argument.I grabbed some info from the 'internets' about approximate case capacity which I've listed below.
6.5 PRC - 68 grs
7 PRC - 73 grs
300 PRC - 77 grs
264 Win Mag - 82 grs
26 Nosler - 93 grs
I've read were Scottw2119 was getting 3200-3300 fps with the 156 EOL out of a 6.5-7 PRC and I think I remember elkaholic saying a customer was getting 3500 fps + out of a 30SM necked down to 6.5. I'm assuming they were using 24"+ barrels. Both of those cases are well below the 264 Win Mag and 26 Nosler in the amount of powder burned and are outperforming them as well. I guess my biggest question is, at what point do you reach diminishing returns in case capacity in relation to speed? Will I be able to find a suitable powder to use in a 20-22" barrel without having a flame thrower? I'm just thinking of ways to add more speed to overcome the shorter barrel length.
Does anyone have any experience with either or both? TIA
DirtNap35
Well-Known Member
I believe UM is building a 6.5-7PRC Improved +P. Sounds really tempting.
I lucked out and got some on Gunbroker.
@SteveBurton
Do you have a velocity goal in mind with the 156? Or are you just trying to get it going as fast as possible in a 20" barrel?
More case doesn't necessarily mean more speed unless you have enough barrel/ bore volume to burn the powder from whatever particular case you decide on.
The more overbore you go and the heavier the bullet the more temperamental things CAN get. I'm sure there are some 6.5-300wby's out there that shoot 1 hole 5 shot groups. But there are more 6.5x47 that do it.
A 6.5x300prc is going to be a flame thrower in a 20" barrel. So if you are shooting suppressed, I hope you can clean your can easily.
I'd look into a 6.5saum-6.5max sized case to do what you are talking about doing.
Do you have a velocity goal in mind with the 156? Or are you just trying to get it going as fast as possible in a 20" barrel?
More case doesn't necessarily mean more speed unless you have enough barrel/ bore volume to burn the powder from whatever particular case you decide on.
The more overbore you go and the heavier the bullet the more temperamental things CAN get. I'm sure there are some 6.5-300wby's out there that shoot 1 hole 5 shot groups. But there are more 6.5x47 that do it.
A 6.5x300prc is going to be a flame thrower in a 20" barrel. So if you are shooting suppressed, I hope you can clean your can easily.
I'd look into a 6.5saum-6.5max sized case to do what you are talking about doing.
Somebody send this guy a case of beer… or a jug of something…!
Great post man!
Barrel lengths make a difference, trying a 15" beside a 16" on my XP100R's for handgun hunting, deer only. Think I'm liking 16" for the 6.5 and 15" on the 7mm.
longtubeman
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Have a 161/2 bull with a break. It's a xp100 old comp gun in 6.5x284, 1 in 10 twist, does 120 ttsx barns at 3000 fps. Very, very, noisy, double ear protection needed! Just turned it into a rifle. Going to run suppressed .
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Calvin45
Well-Known Member
I'm not arguing with you at all, nor finding fault, but I will say my .257 weatherby surprised the heck out of me with how high performing it is even out of a 24 inch barrel. It's even more overbore than the .264 win mag.
For sure a longer pipe is better and more practical and you see much more benefit with longer barrels in overbore cartridges than you do with efficient cartridges.,.but even out of shorter than ideal barrels, at equal barrel lengths at any length the big drag racers will outrun the efficient ones.
Again, not arguing so much as curious what you mean by "won't perform" regarding the .264 Winnie out of a 24.
100%, If gonna run a super short barrel might also benefit more from a bit faster powder
Calvin45
Well-Known Member
I have VERY rarely heard of it that a powder that gives the highest velocity in a given cartridge/bullet combo in a longer barrel gets outrun by a different powder in a shorter one with the same cartridge/bullet. It does happen I'm sure, especially with some of the "weird" progressive burn rate powders like rl26, 17, SUPERFORMANCE, and for sure if we're talking long pistol length barrels shooting full rifle cartridges like those TC contenders or savage strikers and such that's a different ball game too, but it's very much the rule that regardless of barrel length, the powder that gives the highest velocity does so across the spectrum.
There are exceptions to every rule no doubt but the amount of actual chronograph verified data where you'd have a cartridge with two different loads with 2 different powders loaded with the same projectile and the slower burn rate one yielded higher mv out of a long barreled rifle and the faster burn rate one outran it out of a 16-22 inch barrel is almost nil. I've seen such actual proof of this widely accepted and repeated claim (that faster burn rates outperform slower ones in short barrels where they don't in long ones) exactly ONCE on this forum and to be honest couldn't beleive it but was sure glad I saw it. It does happen but it's rare as hens teeth haha.
One thing tho that I can DEFINITELY vouch for in regards to the practicality and benefit of faster than typical burning powder in shorter than typical barrels for a given chambering is the reduction in muzzle blast and flash.
Back when I was more or less a one gun deer hunter with a 22 inch barreled 270 even I found this out. Even from that 22 inch barrel the fastest absolute velocity for 130-150 grain bullets for me was with RL22, h4831, and even the slow burning IMR7828. In fact based on my experience I concluded that the boring old 270 has untapped potential using compressed loads of powders of slower burn rates than typically found in the manual, with 150 soft points i had no trouble exceeding 2950 fps with compressed loads of 7828. But she was LOUD and she breathed serious FIRE!!!!
The loads worked up with imr 4064 and 4350 were never as fast as those ones but, for only being 100-200 fps slower, they sure kicked less, concussed less, and flashed less. As much as it kills me to admit it I'm sure the deer wouldn't have noticed the difference.
