I have a xbolt2 spr 22 inch barrel im loading mid book charges and im pulling high book fps could this be a result of having a 1:8twist instead of a 1:9.5 mono 160 grain cx is the bullet rl22 powder any ideas out there is this normal
7mm rem mag
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Maintenanceman8193
Member
I would say it's not normal, but more information like the load data your using , chronograph, did you calibrate your scale would help , seating depth
thatguyshm
Well-Known Member
My understanding is usually due to either throat design or tight bore. I have a Christensen 30-06 that gives me beyond max values with starting loads. I just us8e the velocity numbers more so than the powder charge with that one.
I'm at 59 grains of RL22 getting 2840 fps, which has a range from Nosler using my exact components as 58.0-62.0 and 2648-2819.
Biggest thing for me is I don't try to turn it in a 300 WM, I just use less powder and keep it in appropriate velocity windows. There is no free lunch, the pressures are still there, just load to velocity and you'll be fine.
I'm at 59 grains of RL22 getting 2840 fps, which has a range from Nosler using my exact components as 58.0-62.0 and 2648-2819.
Biggest thing for me is I don't try to turn it in a 300 WM, I just use less powder and keep it in appropriate velocity windows. There is no free lunch, the pressures are still there, just load to velocity and you'll be fine.
dogz
Well-Known Member
# of grains and the speed you're getting?
Also, I take it this has happened on more than one outing right?
MagnumManiac
Well-Known Member
The only answer is different gun to what was tested equals different outcome.
I have plenty of rifles/barrels that shoot faster than published data, I also have a few barrels that never come close to published data.
Twist rate makes zero difference to pressure and velocity.
Cheers.
I have plenty of rifles/barrels that shoot faster than published data, I also have a few barrels that never come close to published data.
Twist rate makes zero difference to pressure and velocity.
Cheers.
cohunt
Well-Known Member
OP, Are you using load data for the monos or c&c ?
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Chronographs can vary in their accuracy.
Back in my beam scale days I want to say I tossed a set of scales that were off/wouldn't calibrate or wouldn't repeat. Been to many years can't recall.
Last year I tossed a set of Lyman digital scales that wouldn't hold zero. Might have been power supply but didn't want to take a chance so I tossed them too.
I'd be checking my scales and like said above, check I wasn't shooting Barnes etc with cup and core data.
Last year I tossed a set of Lyman digital scales that wouldn't hold zero. Might have been power supply but didn't want to take a chance so I tossed them too.
I'd be checking my scales and like said above, check I wasn't shooting Barnes etc with cup and core data.
82nd Bill
Well-Known Member
When you say exact components does that also been the brass? Some brass is thicker than and that means lower charge weight to hit the same speed. Could also be a tight chamber that would also mean a lower charge but higher speed. Just load to the speed and you should be good to go.
Husqvarna Man
Well-Known Member
I have a Weatherby Back Country 6.5 RPM and I can't get within a grain and half of any max load data.
Does not matter if its Wolf Publication or Hodgeon !
Weatherby or Pederson brass no different.
61 gr of IMR 7828 is a max load with 130's
Does not matter if its Wolf Publication or Hodgeon !
Weatherby or Pederson brass no different.
61 gr of IMR 7828 is a max load with 130's
82nd Bill
Well-Known Member
Agreed and a good Chrono is a must have. Like cajun I do not shoot without one. There are way too many reasons for deviations of speed from book. I noted you are shooting mono's and that can lead to higher fps then most C&C projectiles. My Hammers are typically 50-70 fps faster than C&C.
Always watch for signs of pressure, load test rounds to book info and keep moving. The rifle will tell you what it likes and does not like.
As an additional issue, or complication to your question is that most book info is based on 24" barrels and you are using a 22". That in itself will give you a loss of 20 to 40 fps difference in excepted pfs.
Do a powder check to find your max load and then back off by .5 to 1.0 g and that is your max safe load for your rifle and the ammo you are feeding it. Start the test at the middle of the book load data between min and max. creep up by .3 or .5 gr for each 1 shot load until you reach the very first sign of excess pressure and that is your max load for that rifle with that load. For safe max load I normally back off .5g for non-magnum roads and 1.g for magnum rounds and call that my max load. After that I drop 2.1g from my safe max load and load 3 rounds of with increases of .3g of charge weight to see if I hit an accuracy node.
To start with I would use the load data published by the bullet maker and in your case Hornady. The reason is that they more data about that bullet.
Your question is a good one but too many variables for it to occur. Load it, test it, record the test, believe the data and stay safe.
Always watch for signs of pressure, load test rounds to book info and keep moving. The rifle will tell you what it likes and does not like.
As an additional issue, or complication to your question is that most book info is based on 24" barrels and you are using a 22". That in itself will give you a loss of 20 to 40 fps difference in excepted pfs.
Do a powder check to find your max load and then back off by .5 to 1.0 g and that is your max safe load for your rifle and the ammo you are feeding it. Start the test at the middle of the book load data between min and max. creep up by .3 or .5 gr for each 1 shot load until you reach the very first sign of excess pressure and that is your max load for that rifle with that load. For safe max load I normally back off .5g for non-magnum roads and 1.g for magnum rounds and call that my max load. After that I drop 2.1g from my safe max load and load 3 rounds of with increases of .3g of charge weight to see if I hit an accuracy node.
To start with I would use the load data published by the bullet maker and in your case Hornady. The reason is that they more data about that bullet.
Your question is a good one but too many variables for it to occur. Load it, test it, record the test, believe the data and stay safe.
