High extreme spread...

1stmar · July 12, 2015, 03:18 PM

I have a very short barrel on my mini, 16.5" with the muzzle break so probably 14.5" barrel. Chronograph readings were >100fps spread and high sd. Initially I tried 24.5gr of 4064, lc brass and 55 gr Fimj. I was thinking the es variation was from to slow a burning powder for that length of barrel so I went to a faster burning powder (2230). Same thing, high es.
Not sure in barrel length is a factor or not, or if primer pockets may be leaking?
I use the same process for reloading all rifle calibers, other calibers are single digit sd and low dble digit es.

Metal god · July 12, 2015, 03:38 PM

I have tested how I hold the rifle can change the ES / SD . Next time out try shooting and letting the rifle almost completely freely recoil . Just stay in control of the rifle . My test were with a 13lb 308 with muzzle break so it was easy to control . Your mini should not be to hard to control . Remember this is a velocity test so don't put to much work in group size just get the round over the chrono .

My results were drastic but I did not start with that high of a ES . I was holding my rifle very tight to my shoulder . The lighter my hold got the lower my ES got . I was able to bring down a 36fps ES to 12fps ES with an SD of 5fps just buy how I held the rifle from shot to shot . I don't think you'll drop your ES to 20 or anything but I bet you take off a 1/3 to 1/2 having a consistent hold .

There are other things like inconsistent bullet diameter will cause different internal pressures causing different velocity's .

Changing primers could help

Uniform flash holes

Bullet hold maybe

Road_Clam · July 13, 2015, 05:37 AM

reading into excessive ES can be a frustrating issue to sort out. I too for some reason observe higher ES's when running 4064. Can't explain why. I don't do anything different than when I'm loading W748 , 2000MR , or any of my other medium burn powders. I used to get all worked up when my ES's exceeded 60 fps but now that I've generated a lot of varied velocities and groupings I've realized that I see NO correlation between larger ES's and poor precision. I've shot sub MOA loads and my ES's were up around 70 , and I've shot as poor as 4 moa with ES's in the teens. So in my situation of a recreational shooter I focus on other aspects of precision.

MtnCreek · July 13, 2015, 08:04 AM

There are better powders for 55gr/223 loads. It's a little on the slow side and your load looks to be a little on the mild side. Slowish powder and lowish pressure will often = high SD's.

I wouldn't necessarily trust the chronograph results and high spreads in a 16" mini14 shooting FMJ's is not the end of the world. It's a blaster shooting blaster fodder.

July 12, 2015, 03:18 PM	#1
1stmar Senior Member Join Date: March 21, 2012 Location: Connecticut Posts: 2,378	High extreme spread... I have a very short barrel on my mini, 16.5" with the muzzle break so probably 14.5" barrel. Chronograph readings were >100fps spread and high sd. Initially I tried 24.5gr of 4064, lc brass and 55 gr Fimj. I was thinking the es variation was from to slow a burning powder for that length of barrel so I went to a faster burning powder (2230). Same thing, high es. Not sure in barrel length is a factor or not, or if primer pockets may be leaking? I use the same process for reloading all rifle calibers, other calibers are single digit sd and low dble digit es.

July 12, 2015, 03:38 PM	#2
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,876	I have tested how I hold the rifle can change the ES / SD . Next time out try shooting and letting the rifle almost completely freely recoil . Just stay in control of the rifle . My test were with a 13lb 308 with muzzle break so it was easy to control . Your mini should not be to hard to control . Remember this is a velocity test so don't put to much work in group size just get the round over the chrono . My results were drastic but I did not start with that high of a ES . I was holding my rifle very tight to my shoulder . The lighter my hold got the lower my ES got . I was able to bring down a 36fps ES to 12fps ES with an SD of 5fps just buy how I held the rifle from shot to shot . I don't think you'll drop your ES to 20 or anything but I bet you take off a 1/3 to 1/2 having a consistent hold . There are other things like inconsistent bullet diameter will cause different internal pressures causing different velocity's . Changing primers could help Uniform flash holes Bullet hold maybe __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

July 13, 2015, 05:37 AM	#3
Road_Clam Senior Member Join Date: November 21, 2013 Location: New Hampshire Posts: 1,695	reading into excessive ES can be a frustrating issue to sort out. I too for some reason observe higher ES's when running 4064. Can't explain why. I don't do anything different than when I'm loading W748 , 2000MR , or any of my other medium burn powders. I used to get all worked up when my ES's exceeded 60 fps but now that I've generated a lot of varied velocities and groupings I've realized that I see NO correlation between larger ES's and poor precision. I've shot sub MOA loads and my ES's were up around 70 , and I've shot as poor as 4 moa with ES's in the teens. So in my situation of a recreational shooter I focus on other aspects of precision. __________________ "To be old an wise you must have been young and stupid"

July 13, 2015, 08:04 AM	#4
MtnCreek Senior Member Join Date: December 14, 2010 Posts: 176	There are better powders for 55gr/223 loads. It's a little on the slow side and your load looks to be a little on the mild side. Slowish powder and lowish pressure will often = high SD's. I wouldn't necessarily trust the chronograph results and high spreads in a 16" mini14 shooting FMJ's is not the end of the world. It's a blaster shooting blaster fodder.