Is Group Stringing Indicative of Anything?

black mamba · May 6, 2014, 12:54 PM

Below is a picture of two different loads, both equally accurate, but the first has horizontal stringing, the second has vertical stringing.

Does either example tell us anything about the powder charge that would help us improve the load's accuracy? For example, does vertical stringing mean too little or too much powder, or even too fast or too slow a powder? I'm curious if there are any generalities that can hold true most of the time. Thanks for any input.

Valornor · May 6, 2014, 03:01 PM

Verticle string indicates inconsistent velocity. I.E bullet drop. This could be from inconsistent powder throws to different seating depths ect. Could also be related to how the powder burns, maybe you're using a powder that's more suited for a heavier bullet and it's not burning consistently.

Side ways string, I would think would be wind related, or something touching the barrel. I'm not exactly sure what in a bad load would cause a horizontal string.

I suppose either could be the affects of a barrel heating up, but the first thing I would check with a vertical string on reloads is the consistency of my powder thrower.

Misssissippi Dave · May 6, 2014, 03:14 PM

Am I to assume they are shot from a rest and the exact point of aim is being used? I have seen people complain about some ammo and how accurate it is in the past. Often, it was a problem more of the shooter than anything else.

SpringOWeiler · May 6, 2014, 03:43 PM

It is indicative of frustration

Brian Pfleuger · May 6, 2014, 03:55 PM

You need to know more than just where 5 shots went.

For one, 5 shots could still be nearly truly random. A 30 shot group might end up being very close to round, even when 5 shots "string".

Also, did the shots go 1-5 in a row/column, or was shot 5 and 1 right next to each other? Did it truly "walk the string" or was the placement random?

black mamba · May 6, 2014, 05:17 PM

Good points, all. I'm talking primarily about handguns here, fired from a sandbag rest, so forearm bedding pressure, etc., is not really an issue. The same revolver, firing the same bullets with different powders, has fired both such groups.

One load work up fired a vertically strung group with load A, then load B with ½ grain more powder shot a pretty symmetrical group, and load C with another ½ grain more powder shot a horizontal group. I don't recall that being typical of other load workups, and I've been handloading for almost 40 years. I just wondered if that was a regular pattern.

I'll need to pay more attention to the order the shots print, if the shots actually "walk" in one direction, or not. More shots in the group is also a good idea.

Misssissippi Dave · May 6, 2014, 06:05 PM

A couple things I have found when using a revolver testing loads.

Sometimes it is good to try using the same cylinder for the test. There is a chance other cylinders could influence slight differences. I could be wrong but it might be worth trying.

Waiting for the gun to achieve the same temperature for each shot might tighten the group up as well. If it does help, the the barrel and cylinder changing temperatures is possibly effecting things. An older semi-auto pistol I have seems to get better grouping after firing a few rounds to warm the barrel up. When it gets hot accuracy does down.

pathdoc · May 7, 2014, 05:23 PM

Of course the problem with letting the handgun cool between shots is that if the shooter is doing something that demands a lot of shooting in very short order (some sort of competition, for example), that isn't an option.

My experience with really gross vertical stringing (in a rifle, admittedly) is that charge weight variations are to blame - or at least should be the first thing looked at. When I weighed the charges instead of just scooped them (which I did purely to see what would happen), the stringing tightened up remarkably. If you're sure about your charge weights, move on to other potential causes.

McShooty · May 9, 2014, 10:11 AM

Aha! A handgun, huh? For me, inconsistent ignition, which can cause vertical stringing in a rifle, is rarely a problem with handguns. With the short arm, it will have more to do with how the gun is rested and held by the shooter.

mikld · May 9, 2014, 10:47 AM

Another consideration for handguns, especially revolvers; where does the gun rest? On the barrel near the muzzle? On the grip frame? May make a difference in groups...

Slamfire · May 9, 2014, 12:09 PM

Hitting the trigger too hard causes vertical stringing. Shoot enough small bore prone and you will see it.

May 6, 2014, 12:54 PM	#1
black mamba Senior Member Join Date: September 13, 2011 Location: SW Florida Posts: 890	Is Group Stringing Indicative of Anything? Below is a picture of two different loads, both equally accurate, but the first has horizontal stringing, the second has vertical stringing. Does either example tell us anything about the powder charge that would help us improve the load's accuracy? For example, does vertical stringing mean too little or too much powder, or even too fast or too slow a powder? I'm curious if there are any generalities that can hold true most of the time. Thanks for any input.

May 6, 2014, 03:01 PM	#2
Valornor Senior Member Join Date: March 18, 2010 Location: Orem, Utah Posts: 244	Is Group Stringing Indicative of Anything? Verticle string indicates inconsistent velocity. I.E bullet drop. This could be from inconsistent powder throws to different seating depths ect. Could also be related to how the powder burns, maybe you're using a powder that's more suited for a heavier bullet and it's not burning consistently. Side ways string, I would think would be wind related, or something touching the barrel. I'm not exactly sure what in a bad load would cause a horizontal string. I suppose either could be the affects of a barrel heating up, but the first thing I would check with a vertical string on reloads is the consistency of my powder thrower.

May 6, 2014, 03:55 PM	#5
Brian Pfleuger Moderator Emeritus Join Date: June 25, 2008 Location: Austin, CO Posts: 19,578	You need to know more than just where 5 shots went. For one, 5 shots could still be nearly truly random. A 30 shot group might end up being very close to round, even when 5 shots "string". Also, did the shots go 1-5 in a row/column, or was shot 5 and 1 right next to each other? Did it truly "walk the string" or was the placement random? __________________ Nobody plans to screw up their lives... ...they just don't plan not to. -Andy Stanley

May 9, 2014, 10:47 AM	#10
mikld Senior Member Join Date: February 7, 2009 Location: Southern Oregon! Posts: 2,891	Another consideration for handguns, especially revolvers; where does the gun rest? On the barrel near the muzzle? On the grip frame? May make a difference in groups... __________________ My Anchor is holding fast! I've learned how to stand on my own two knees...

May 9, 2014, 12:09 PM	#11
Slamfire Senior Member Join Date: May 27, 2007 Posts: 5,261	Hitting the trigger too hard causes vertical stringing. Shoot enough small bore prone and you will see it. __________________ If I'm not shooting, I'm reloading.

May 6, 2014, 03:14 PM	#3
Misssissippi Dave Senior Member Join Date: December 5, 2009 Posts: 1,411	Am I to assume they are shot from a rest and the exact point of aim is being used? I have seen people complain about some ammo and how accurate it is in the past. Often, it was a problem more of the shooter than anything else.

May 6, 2014, 03:43 PM	#4
SpringOWeiler Senior Member Join Date: February 28, 2014 Location: Washington (Dry Side) Posts: 116	It is indicative of frustration

May 6, 2014, 05:17 PM	#6
black mamba Senior Member Join Date: September 13, 2011 Location: SW Florida Posts: 890	Good points, all. I'm talking primarily about handguns here, fired from a sandbag rest, so forearm bedding pressure, etc., is not really an issue. The same revolver, firing the same bullets with different powders, has fired both such groups. One load work up fired a vertically strung group with load A, then load B with ½ grain more powder shot a pretty symmetrical group, and load C with another ½ grain more powder shot a horizontal group. I don't recall that being typical of other load workups, and I've been handloading for almost 40 years. I just wondered if that was a regular pattern. I'll need to pay more attention to the order the shots print, if the shots actually "walk" in one direction, or not. More shots in the group is also a good idea.

May 6, 2014, 06:05 PM	#7
Misssissippi Dave Senior Member Join Date: December 5, 2009 Posts: 1,411	A couple things I have found when using a revolver testing loads. Sometimes it is good to try using the same cylinder for the test. There is a chance other cylinders could influence slight differences. I could be wrong but it might be worth trying. Waiting for the gun to achieve the same temperature for each shot might tighten the group up as well. If it does help, the the barrel and cylinder changing temperatures is possibly effecting things. An older semi-auto pistol I have seems to get better grouping after firing a few rounds to warm the barrel up. When it gets hot accuracy does down.

May 7, 2014, 05:23 PM	#8
pathdoc Senior Member Join Date: February 12, 2013 Posts: 669	Of course the problem with letting the handgun cool between shots is that if the shooter is doing something that demands a lot of shooting in very short order (some sort of competition, for example), that isn't an option. My experience with really gross vertical stringing (in a rifle, admittedly) is that charge weight variations are to blame - or at least should be the first thing looked at. When I weighed the charges instead of just scooped them (which I did purely to see what would happen), the stringing tightened up remarkably. If you're sure about your charge weights, move on to other potential causes.

May 9, 2014, 10:11 AM	#9
McShooty Senior Member Join Date: January 4, 2012 Location: Northern Missouri Posts: 480	Aha! A handgun, huh? For me, inconsistent ignition, which can cause vertical stringing in a rifle, is rarely a problem with handguns. With the short arm, it will have more to do with how the gun is rested and held by the shooter.