I can tell you we went from 2741 to 2281 26" to 18"
on a creedmoor
will check on the 7 prc
on a creedmoor
will check on the 7 prc
7mm PRC Shorter Barrel Twist Rate
- Thread starter brianortegojr
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- barrel twist rates
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Jakeweb09
Well-Known Member
I've shot 130 eldms from a 18.5" creed at 2800, and a buddy has one at 18" shooting 140s at 2730
Bartlein 8 twist, went with mod400BB for this one
Beaver10
Well-Known Member
I chrono'd the speed of my Seekins Element 7PRC with a 22" tube. With just 40 rounds of Hornady 175gr Eld-X thru the barrel. I was getting some pedestrian numbers, imo.
Hoping I will pick up a smidge more velocity after the barrel burns in more.
Average of 4 shots from 4 different boxes on ammo 2705 FPS
Hoping I will pick up a smidge more velocity after the barrel burns in more.
Average of 4 shots from 4 different boxes on ammo 2705 FPS
entoptics
Well-Known Member
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Same lot # for all four boxes?
That's 150 fps/in of velocity loss compared to Hornady's quoted speed (and quite a few interwebs reports of close enough to 3000 fps in a 24"). Even if it speeds up 100 fps after a couple hundred rounds (unlikely), that's still 100 fps/in loss.
Personally, If I recorded that data, I'd be calling Hornady or Seekins or both after I checked my chronograph to make sure something wasn't broken...
Beaver10
Well-Known Member
I've been racking my head over it, looking for an easy explanation. Tomorrow, I'm going to pull the muzzle brake off and see if the numbers increase dramatically.
I've chrono'd a lot of rifles with the brake on and never had any questionable data.
If I don't see improvements putting me into at least the high 2800's. Phone calls will be made Monday.
I've chrono'd a lot of rifles with the brake on and never had any questionable data.
If I don't see improvements putting me into at least the high 2800's. Phone calls will be made Monday.
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Lefty7mmstw
Well-Known Member
It's not that often you see that kind of loss, but it happens. I had a 30-06 for a spell that was 2650 fps with a 165 Hornady and I 4350 topped out. I've had a few other 30-06 rifles that have run in the 2800-2900 fps range with the same load. My current rifle is just over 2800 fps. I've also seen this with 7mmstw's pushing 140's with rl25. My Accubond load was a bit over 3400 fps in my old Sendero, 3280 fps in the 24" tube on my lh rifle when I got it, and mid 33's with my current 27" Shilen.
You can't do much about it other than amputating the barrel and hoping the new one is faster or tailoring a load to your current barrel.
You can't do much about it other than amputating the barrel and hoping the new one is faster or tailoring a load to your current barrel.
Makes you wonder if they switched powders at some point from what the early factory loadings were using.
lancetkenyon
Well-Known Member
I think a 1:8" would be more than sufficient. The only bullets that would need that twist are the 195 EOL or 197 SMK, or a heavyweight mono. Even the 177 HH would do fine in a 1:8".
My 24" 1:8.4" 7SS is shooting the 184 Hybs, and it is wicked stable and accurate out past 1500 yards. It is probably on par with a 22" 7PRC. Depending on which powder, my two loads are 2798fps w. H1000 or 2916fps w. RL26.
My 24" 1:8.4" 7SS is shooting the 184 Hybs, and it is wicked stable and accurate out past 1500 yards. It is probably on par with a 22" 7PRC. Depending on which powder, my two loads are 2798fps w. H1000 or 2916fps w. RL26.
Lefty7mmstw
Well-Known Member
They could have. usually there are at least a couple of powders that make spec. for a load. It's a good reason to buy one lot number up if it shoots for you; the next lot may well be with another powder or another lot of the same powder.
Am going through the same thing. Want as short of barrel as I can get. But looking at way closer yardage. 600 max. This would also be for Elk . How short can I get away with?
Honestly I think you'd be completely fine with. 20" barrel but you can also do a 22" if you want a bit more "security." My build is intended for n inside 600 yd rifle and I honestly expect 95%+ to really be in the under 400 yard range in real life since I live East of the Mississippi River.
Yes 600 yards would be the maximum distance. Same as you probably under 400 yards. This is for my wife and want to make as short as possible. Would even go 18 if I can get away with it? One concern I have is if you put a brake on it being that short I'm thinking that it going to be brutal on the shooter's ears?
