I’m going to be adding to this, providing links to screenshots and some interesting observations I made of the data over the next week or two but I wanted to make an initial presentation of the data before any more time went by.
The links will be added here at the top of this post for those few, who don’t fall into a coma after trying to digest my ramblings below.
New Link: Red Rifle w 12-pin Observations
New Link: Some Rifle/Ammo Characteristics & Measuring Tools
New Link: Red Rifle w 12-pin Observations
New Link: Some Rifle/Ammo Characteristics & Measuring Tools
Dan’s Test Methodology as Reported to me:
All testing was done at 50 yards indoors off a Pappas one-piece rest on sturdy concrete benches
We shot 2 rifles, Blue and Red, with both bolts.
We shot 2 rifles, Blue and Red, with both bolts.
Blue Rifle with 6 bolt had a headspace of .046
Blue Rifle with 12 bolt had a headspace of .044
Red Rifle with 6 bolt had a headspace of .042
Red Rifle with 12 bolt had a headspace of .044
Procedure was as follows:
bolt
-fire 5 fouler shots
-fire 1 complete target in order
-swap to bolt
-fire 3 fouler shots
-fire complete target in order
-clean rifle
-fire 5 fouler shots
bolt stays
-fire complete target
-Swap to bolt
-fire complete target
We did this routine 1.5 times for each rifle. So 3 targets for each bolt with each rifle. I wanted to do more, but this took us about 5 hours. Swapping the bolts around was a real pain.
Firing Pin Strike Depth’s Correlation to Velocity & Accuracy:
There were too many combinations of rifles and bolts along with a large variation in strike depth with each combination to show other than a very weak correlation to velocity.
Trying to make a correlation to accuracy was even more difficult and I gave up.
The best I can do is provide a series of charts that visually depict the velocity characteristics of each combination and a chart showing how strike depths with these specific bolts are changed at a 2:1 ratio by headspace increases.
Link: Firing Pin Strike Depth
I do have a question for all of you though. Looking at all these charts I get the impression that good ignition was easy to achieve with these rifles, but I don’t know what the firing pin’s mass is or how much spring force is present with the bolt/pin combinations. I’m curious if the rest of you get the same impression after viewing the charts? Remember, I’m looking at only a possible correlation with velocity and I’m assuming most of you will know there may be a correlation to accuracy that’s independent of ignition alone, because of specific differences in the mass and acceleration of different firing pins and their effects on how the rifle “moves” when this energy is released and impacts the cartridge.
The chronograph data:
75 rounds with each configuration of rifle/bolt for a total of 300 rounds fired.
Red rifle with 12-pin bolt: Avg 1044 fps and 9.2 fps Std D
Red rifle with 6-pin bolt: Avg 1047 fps and 9.1 fps Std D
Blue rifle with 12-pin bolt: Avg 1036 fps and 8.4 fps Std D
Blue rifle with 6-pin bolt: Avg 1035 fps and 7.0 fps Std D
In the case of the Red rifle, we have a range of (1034.8 to 1053.2) for the 12-pin and (1037.9 to 1056.1) for the 6-pin. These 2 sets of data overlap to the point of being almost unusual and if you were to shoot 2 tests using only the 12-pin or 6-pin….it wouldn’t be surprising to see a larger difference with the same pin.
This is a simplified explanation that I shouldn’t need to make and there are other factors to be considered when using it, but understanding at least this much is mandatory. Judging by the posts I see on most internet forums, there are great number of shooters who “don’t” understand this and maybe this will be helpful to a few.
6-pin vs 12-pin Summery:
GAP Avg of 3-25 Shot Grps and Grp ES Avg of 15x5 Shot Grps
Red rifle 6-pin bolt: (0.203” +/-0.027 GAP) (0.251” Avg & 0.082 Std D) 2158 ARA
Red rifle 12-pin bolt: (0.186” +/-0.028 GAP) (0.246” Avg & 0.109 Std D) 2225 ARA
Blue rifle 6-pin bolt: (0.185” +/-0.024 GAP) (0.240” Avg & 0.051 Std D) 2233 ARA
Blue rifle 12-pin bolt: (0.200” +/-0.023 GAP) (0.265” Avg & 0.064 Std D) 2167 ARA
The GAP software I use is the most efficient statistical means of measuring the size of a grouping and generating the uncertainties necessary to make comparisons with the fewest number of shots. It’s the most important number to look at and I’ll provide a link with a better explanation at the top of this post later.
In this case it doesn’t matter if you use the GAP statistics or the group ES statistics because there are no significant differences with either means of measurement.
I’m going to state my conclusions very carefully and I want you to pay scrupulous attention to where I place the parenthesis in the following statement:
With “these” specific rifles, “these” specific bolts, “these” specific headspaces, and “this” specific test….there is nothing in the data to suggest either pin is significantly different as regards velocity, uniformity of velocity, or accuracy.
That doesn't mean there isn't a difference, it just means this test didn't show it.
That doesn't mean there isn't a difference, it just means this test didn't show it.
Results for each configuration of rifle/bolt and all 12 targets:
Red Rifle w 6 Bolt (Target 1):
GAP Width 25-Shot Grp: (0.226”) +/-0.047”
5x5-Shot Grp Avg: (0.287”ES) Min 0.168” Max 0.476” SD 0.116”
ARA Score: (2075)
Chronograph Results:
1042 fps and 8.6 SD
Red Rifle w 6 Bolt (Target 2):
GAP Width 25-Shot Grp: (0.179”) +/-0.038”
5x5-Shot Grp Avg: (0.210”ES) Min 0.134” Max 0.257” SD 0.051”
ARA Score: (2300)
Chronograph Results:
1051 fps and 7.6 SD
Red Rifle w 6 Bolt (Target 3):
GAP Width 25-Shot Grp: (0.205”) +/-0.053”
5x5-Shot Grp Avg: (0.256”ES) Min 0.192” Max 0.332” SD 0.061”
ARA Score: (2100)
Chronograph Results:
1049 fps and 8.5 SD
Red Rifle w 6 Bolt (All Targets - 75 Shots):
GAP Width Avg: (0.203”) +/-0.027"
15x5-Shot Grp Avg: (0.251”ES) Min 0.134” Max 0.476” SD 0.076”
ARA Score Avg for 3 Targets: (2158)
Chronograph Results:
1047 fps and 9.1 SD
Red Rifle w 12 Bolt (Target 1):
GAP Width 25-Shot Grp: (0.252”) +/-0.066”
5x5-Shot Grp Avg: (0.354”ES) Min 0.268” Max 0.480” SD 0.091”
ARA Score: (1975)
Chronograph Results:
1041 fps and 12.8 SD
Red Rifle w 12 Bolt (Target 2):
GAP Width 25-Shot Grp: (0.162”) +/-0.040”
5x5-Shot Grp Avg: (0.226”ES) Min 0.134” Max 0.305” SD 0.079”
ARA Score: (2300)
Chronograph Results:
1043 fps and 7.2 SD
Red Rifle w 12 Bolt (Target 3):
GAP Width 25-Shot Grp: (0.145”) +/-0.032”
5x5-Shot Grp Avg: (0.159”ES) Min 0.102” Max 0.229” SD 0.052”
ARA Score: (2400)
Chronograph Results:
1046 fps and 5.7 SD
Red Rifle w 12 Bolt (All Targets - 75 Shots):
GAP Width Avg: (0.186”) +/-0.028"
15x5-Shot Grp Avg: (0.246”ES) Min 0.102” Max 0.480” SD 0.109”
ARA Score Avg for 3 Targets: (2225)
Chronograph Results:
1044 fps and 9.2 SD
Blue Rifle w 6 Bolt (Target 1):
GAP Width 25-Shot Grp: (0.173”) +/-0.037”
5x5-Shot Grp Avg: (0.204”ES)-0.172”-0.234”-SD 0.028”
ARA Score: (2300)
Chronograph Results:
1032 fps and 6.9 SD
Blue Rifle w 6 Bolt (Target 2):
GAP Width 25-Shot Grp: (0.194”) +/-0.042”
5x5-Shot Grp Avg: (0.272”ES)-0.220”-0.325”-SD 0.047”
ARA Score: (2100)
Chronograph Results:
1038 fps and 6.0 SD
Blue Rifle w 6 Bolt (Target 3):
GAP Width 25-Shot Grp: (0.189”) +/-0.043”
5x5-Shot Grp Avg: (0.244”ES)-0.171”-0.320”-SD 0.055”
ARA Score: (2300)
Chronograph Results:
1035 fps and 6.8 SD
Blue Rifle w 6 Bolt (All Targets - 75 Shots):
GAP Width Avg: (0.185”) +/-0.024"
15x5-Shot Grp Avg: (0.240”ES) Min 0.171” Max 0.325” SD 0.051”
ARA Score Avg for 3 Targets: (2233)
Chronograph Results:
1035 fps and 7.0 SD
Blue Rifle w 12 Bolt (Target 1):
GAP Width 25-Shot Grp: (0.199”) +/-0.044”
5x5-Shot Grp Avg: (0.268”ES) Min 0.211” Max 0.336” SD 0.055”
ARA Score: (2150)
Chronograph Results:
1034 fps and 7.7 SD
Blue Rifle w 12 Bolt (Target 2):
GAP Width 25-Shot Grp: (0.217”) +/-0.042”
5x5-Shot Grp Avg: (0.293”ES) Min 0.192” Max 0.368” SD 0.066”
ARA Score: (2050)
Chronograph Results:
1033 fps and 8.7 SD
Blue Rifle w 12 Bolt (Target 3):
GAP Width 25-Shot Grp: (0.183”) +/-0.033”
5x5-Shot Grp Avg: (0.234”ES) Min 0.142” Max 0.325” SD 0.069”
ARA Score: (2300)
Chronograph Results:
1040 fps and 7.8 SD
Blue Rifle w 12 Bolt (All Targets - 75 Shots):
GAP Width Avg: (0.200”) +/-0.023"
15x5-Shot Grp Avg: (0.265”ES) Min 0.142” Max 0.368” SD 0.063”
ARA Score Avg for 3 Targets: (2167)
Chronograph Results:
1036 fps and 8.4 SD
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