New Chronograph - The Firearms Forum

verdejt · 03-20-2005, 06:02 PM

Anybody have any information or have chronographed factory ammo. Anybody have any data for standard deviation. I tried out my new chrono with some reloads and for 27 rounds I have a Average velocity of 872.41 and a standard deviation of 28.74. Since I just really started caring about the quality of my reloads (not that I didn't before, Just now I want some hard fast numbers) How does this compare to off the shelf ammo. I need something to quantify my readings from this afternoon. The sun went down before I could shoot an equal number of factory rounds.

inplanotx · 03-20-2005, 09:44 PM

Dumb question time. What are you shooting and what is the bullet weight from a how long barrel?

verdejt · 03-21-2005, 03:36 PM

Sorry, I'm shooting .357mag with 158 gr LSWC from a Taurus Titanium with a 2" barrel.

inplanotx · 03-21-2005, 06:48 PM

Sounds like you are doing pretty well. It is hard trying to compare two guns to each other as all are different even though they are made by the same manufacturer. You need to worry about your gun. Please list the load you are using. Case, primer, powder, amount of powder and so on. Next, tell us if you started off with each case being measured for length. If so, did you trim each one so that all were the same length? If not, then I advise that you do this. Also, were the brass from the same lot from the same manufacturer? If not, then you are going to get inherent differences between each shot.

The crimp has a lot to do with getting the SD down between shots. In order to do this you need to make sure the case volumes of EACH case are the same. This is why we use the same lot number brass to begin with. The only other way is to measure each case and get the case volume of each one. Without this, you cannot bring down the SD.

Let us know where you want to start.

verdejt · 03-21-2005, 09:40 PM

I'm using new Winchester brass and they are from the same lot. I'm loading 5.2 grains of unique with a cci mag pistol primer. I've loaded them with 158gr LSWC. I did check them for OAL and they are pretty close to the same within +/- .02 inches. I didn't measure the empty case length. I am using a lee factory crimp die. This die has no indicator as to how much you are actually crimping. I just set if per the instructions so as not to over crimp and drive the brass deep into the projectile.

inplanotx · 03-22-2005, 10:04 AM

That load sounds pretty mild to me. With 5.2gr of Unique, why are you using a magnum primer? There is no need of one. Never had Unique not go bang with a regular primer. I will look up some loads for a 2" barrel with your LSWC bullet and get back to you.

03-20-2005, 06:02 PM	#1
verdejt V.I.P. Member Join Date: Jan 2005 Posts: 59	New Chronograph Anybody have any information or have chronographed factory ammo. Anybody have any data for standard deviation. I tried out my new chrono with some reloads and for 27 rounds I have a Average velocity of 872.41 and a standard deviation of 28.74. Since I just really started caring about the quality of my reloads (not that I didn't before, Just now I want some hard fast numbers) How does this compare to off the shelf ammo. I need something to quantify my readings from this afternoon. The sun went down before I could shoot an equal number of factory rounds. __________________ It is better to have and not need than to need and not have. -->

03-20-2005, 09:44 PM	#2
inplanotx Advanced Senior Member Join Date: Jan 2002 Location: Texas Posts: 8,897	Re: New Chronograph Dumb question time. What are you shooting and what is the bullet weight from a how long barrel? __________________

03-21-2005, 03:36 PM	#3
verdejt V.I.P. Member Join Date: Jan 2005 Posts: 59	Re: New Chronograph Sorry, I'm shooting .357mag with 158 gr LSWC from a Taurus Titanium with a 2" barrel. __________________ It is better to have and not need than to need and not have.

03-21-2005, 06:48 PM	#4
inplanotx Advanced Senior Member Join Date: Jan 2002 Location: Texas Posts: 8,897	Re: New Chronograph Sounds like you are doing pretty well. It is hard trying to compare two guns to each other as all are different even though they are made by the same manufacturer. You need to worry about your gun. Please list the load you are using. Case, primer, powder, amount of powder and so on. Next, tell us if you started off with each case being measured for length. If so, did you trim each one so that all were the same length? If not, then I advise that you do this. Also, were the brass from the same lot from the same manufacturer? If not, then you are going to get inherent differences between each shot. The crimp has a lot to do with getting the SD down between shots. In order to do this you need to make sure the case volumes of EACH case are the same. This is why we use the same lot number brass to begin with. The only other way is to measure each case and get the case volume of each one. Without this, you cannot bring down the SD. Let us know where you want to start. __________________

03-21-2005, 09:40 PM	#5
verdejt V.I.P. Member Join Date: Jan 2005 Posts: 59	Re: New Chronograph I'm using new Winchester brass and they are from the same lot. I'm loading 5.2 grains of unique with a cci mag pistol primer. I've loaded them with 158gr LSWC. I did check them for OAL and they are pretty close to the same within +/- .02 inches. I didn't measure the empty case length. I am using a lee factory crimp die. This die has no indicator as to how much you are actually crimping. I just set if per the instructions so as not to over crimp and drive the brass deep into the projectile. __________________ It is better to have and not need than to need and not have.

03-22-2005, 10:04 AM	#6
inplanotx Advanced Senior Member Join Date: Jan 2002 Location: Texas Posts: 8,897	Re: New Chronograph That load sounds pretty mild to me. With 5.2gr of Unique, why are you using a magnum primer? There is no need of one. Never had Unique not go bang with a regular primer. I will look up some loads for a 2" barrel with your LSWC bullet and get back to you. __________________