1/2 MOA at 100 yards, all day, every day!

[jgraves]

I haven't looked at any of the data too closely yet, and I fully expected the data to be poor quality due to the short distance. My priority was to collect and compile sample data while I had an opportunity and my OnTarget TDS trial was still active. The chronograph errors should be a relatively fixed magnitude while the velocity difference will increase with distance, improving the signal to noise ratio.

Average BC will be easy to determine (iterate in a ballistics app) but time consuming to do on a per shot basis. Can anyone suggest a more efficient way of calculating individual BC's for many shots?

 

[6.5SH]

I haven't looked at any of the data too closely yet, and I fully expected the data to be poor quality due to the short distance. My priority was to collect and compile sample data while I had an opportunity and my OnTarget TDS trial was still active. The chronograph errors should be a relatively fixed magnitude while the velocity difference will increase with distance, improving the signal to noise ratio.

Average BC will be easy to determine (iterate in a ballistics app) but time consuming to do on a per shot basis. Can anyone suggest a more efficient way of calculating individual BC's for many shots?

Make an Excel sheet to apply your near and far velocity (and distance and air density...) to a formula.

Calculating a Ballistic Coefficient (BC) from two velocities

I have been attempting to calculate a Ballistic Coefficient (BC) from two velocities of a known distance using the formula: BC = (AirDensity * Distance) / ( SQRT(Velocity0) - SQRT(Velocity1)) for example AirDensity = 0.0751265 lb/ft³ Distance = 100 yards Velocity0 = 3000 fps Velocity1 = 2772...

www.physicsforums.com

Ballistic coefficient calculation NEW – Sellier & Bellot

www.sellier-bellot.cz

 

[bulletbluesky]

Speakin' of which Lapua advertises their 22 LR bullets to have BC=0.172 G1
https://www.lapua.com/cartridges/center-x-22-lr/
What do you think of this claim?

 

[6.5SH]

Speakin' of which Lapua advertises their 22 LR bullets to have BC=0.172 G1
https://www.lapua.com/cartridges/center-x-22-lr/
What do you think of this claim?

At the claimed 75 yards, sure.

 

[bulletbluesky]

At the claimed 75 yards, sure.

I think it's a bogus claim. Especially if 75 yards are only considered without specifying muzzle velocity. It could be cherry picking from real data, or even worse-just computed from bullet shape. Custom drag curve should be better published instead. Besides, constancy of drag profile is more important at usual shooting distances than high number. Smells like an old trick for selling ammo!

 

[Cowpokey]

I think it's a bogus claim. Especially if 75 yards are only considered without specifying muzzle velocity. It could be cherry picking from real data, or even worse-just computed from bullet shape. Custom drag curve should be better published instead. Besides, constancy of drag profile is more important at usual shooting distances than high number. Smells like an old trick for selling ammo!

BC isn't a set thing just because of the ammo, or what the manufacturer prints in their specs. With my Vudoo 20" barrel, SKRM MV 1,078fps my Kestrel 5700 Elite needs a BC of 0.158 in order for it to calculate drops correctly.

Also doesn't mean 0.158 is going to be correct for any of my other rifles, using the same ammo, in the same environmental conditions.

 

[lil'skeet]

Now that I have your attention, how? What does it take to produce 1/2 MOA(ish) groups on demand? Is it even possible with 22LR and if so, with what caveats?

There are enough 6x5 averages posted in the 1/2 MOA range that it can't be a statistical anomaly. There are some extremely skilled shooters on this forum with the best available equipment. Personally, I consider myself a mechanically good shooter with good equipment. I would guess I'm capable of holding sub 1/8" MOA from a bench or prone with a bipod and squishing rear bag. I shoot a V-22 with 18" Bartlein MTU barrel. During ammo testing I averaged 0.905 MOA at 104 yards over 10x 10 shot groups with the best lot of Lapua X-Act. I had a calibrated wind flag at 50 yards and tried to fire all shots with less than 2.5 - 3 mph crosswind. I'm admittedly a novice with reading wind. I made no effort to compensate for wind during these groups.

For those that have posted averages in the 1/2 MOA range, could you do so on any day, or were those days "special"? Could you do so throughout the day, on any "average" day, or were those groups shot on the one day every 3 years where there is no wind between 6:45 and 7am? Are you shooting indoors? Are you talanted enough to shoot 1/2 MOA in variable winds without flags? I would like to believe it's possible but rare.

My perception is it takes a lot of ammo well matched to the gun, with either an exceptionally good shooter compensating for wind, or exceptionally good conditions. If I were to offer a $100k bet for you could show up at my range tomorrow, regardless of conditions, and produce 10x 10 shoot groups with a sub-1/2 MOA average, would anyone be interested and how would they approach it? What does it take to go from 1 MOA to 1/2 MOA groups (consistantly)?

For anyone curious, here are my results from X-Act testing along with my best target.

Series	Ammo	Lot	Brake	Shots:	Space	Group ES	Group SD	Group Mean	Target	Space2	Min	Max	Avg	S-D	ES
5	X-Act	26557/709904	Yes	10		1.393	0.187	0.739	X-Act 04 A		1068	1080	1075	3.967	12
6	X-Act	30555/706293	Yes	10		1.422	0.241	0.718	X-Act 93 A		1082	1111	1092	8.985	29
7	X-Act	27557/700011	Yes	10		0.848	0.165	0.454	X-Act 11 A		1076	1095	1088	7.152	19
8	X-Act	26557/709904	Yes	10		0.779	0.14	0.405	X-Act 04 B		1071	1088	1080	5.735	17
9	X-Act	30555/706293	Yes	10		1.023	0.189	0.539	X-Act 93 B		1074	1102	1091	8.548	28
10	X-Act	27557/700011	Yes	10		0.892	0.126	0.475	X-Act 11 B		1082	1100	1089	5.355	18
11	X-Act	26557/709904	Yes	10		1.465	0.244	0.778	X-Act 04 C		1075	1092	1083	5.187	17
12	X-Act	30555/706293	Yes	10		1.181	0.202	0.655	X-Act 93 C		1094	1102	1097	2.807	8
13	X-Act	27557/700011	Yes	10		0.85	0.131	0.474	X-Act 11 C		1081	1099	1092	5.681	18
14	X-Act	26557/709904	Yes	10		1.052	0.172	0.597	X-Act 04 D		1072	1094	1081	7.972	22
15	X-Act	30555/706293	Yes	10		1.356	0.235	0.725	X-Act 93 D		1089	1107	1099	5.519	18
16	X-Act	27557/700011	Yes	10		0.824	0.157	0.434	X-Act 11 D		1084	1104	1093	6.367	20
17	X-Act	26557/709904	Yes	10		1.718	0.383	0.865	X-Act 04 E		1072	1103	1086	8.638	31
18	X-Act	30555/706293	Yes	10		1.041	0.156	0.589	X-Act 93 E		1076	1103	1092	7.226	27
19	X-Act	27557/700011	Yes	10		1.09	0.217	0.616	X-Act 11 E		1080	1105	1096	7.763	25
20	X-Act	26557/709904	No	9		1.228	0.169	0.654	X-Act 04 G		1076	1091	1083	4.676	15
21	X-Act	30555/706293	No	10		1.108	0.158	0.608	X-Act 93 G		1091	1105	1098	4.552	14
22	X-Act	27557/700011	No	10		0.966	0.155	0.514	X-Act 11 G		1091	1111	1101	6.996	20
23	X-Act	26557/709904	No	10		1.824	0.299	0.945	X-Act 04 H		1065	1103	1081	11.06	38
24	X-Act	30555/706293	No	10		0.973	0.183	0.513	X-Act 93 H		1089	1109	1098	6.59	20
25	X-Act	27557/700011	No	10		0.847	0.161	0.487	X-Act 11 H		1082	1109	1099	8.003	27
26	X-Act	26557/709904	No	10		1.444	0.252	0.732	X-Act 04 I		1060	1096	1079	13.5	36
27	X-Act	30555/706293	No	10		1.035	0.231	0.565	X-Act 93 I		1091	1119	1103	8.346	28
28	X-Act	27557/700011	No	10		0.684	0.108	0.374	X-Act 11 I		1088	1106	1096	6.498	18
29	X-Act	26557/709904	No	10		1.412	0.228	0.754	X-Act 04 J		1073	1103	1084	8.68	30
30	X-Act	30555/706293	No	10		1.396	0.241	0.76	X-Act 93 J		1092	1119	1104	8.247	27
31	X-Act	27557/700011	No	10		0.942	0.164	0.54	X-Act 11 J		1094	1113	1102	7.593	19
32	X-Act	26557/709904	No	10		1.325	0.223	0.674	X-Act 04 K		1066	1107	1084	10.54	41
33	X-Act	30555/706293	No	10		1.359	0.237	0.732	X-Act 93 K		1093	1112	1102	6.004	19
34	X-Act	27557/700011	No	10		1.1	0.245	0.584	X-Act 11 K		1083	1110	1100	8.367	27

This is my best group from the session. Excluding the high right shot, it is 0.485 MOA. As a point of reference, a 1mph change in crosswind component accounts for 1/2" deviation in that shot.

Jeff

I would love to see 1|2 moa outdoors with consistency. I personally don't think it's possible with .22lr.
Indoors, more controlled climate I think you may have a chance, but it does not take much to change the trajectory of 22lr.
It's a great goal to chase though.

 

[bulletbluesky]

BC isn't a set thing just because of the ammo, or what the manufacturer prints in their specs. With my Vudoo 20" barrel, SKRM MV 1,078fps my Kestrel 5700 Elite needs a BC of 0.158 in order for it to calculate drops correctly.

Also doesn't mean 0.158 is going to be correct for any of my other rifles, using the same ammo, in the same environmental conditions.

Drops up to 75 yards or so are more sensitive to MVs than to BC figure.
BC varies with velocity unless one deals with a projectile of one of standard drag function shape.
The variability is especially touchy in transonic range, where 22 LR usually shots in.
Also, as you said, under such conditions, an average BC (calculated from near and far velocity tests) depends on particular rifle used too.
These influences would be smaller at longer range (150-200 y).

 

[Cowpokey]

Drops up to 75 yards or so are more sensitive to MVs than to BC figure.
BC varies with velocity unless one deals with a projectile of one of standard drag function shape.
The variability is especially touchy in transonic range, where 22 LR usually shots in.
Also, as you said, under such conditions, an average BC (calculated from near and far velocity tests) depends on particular rifle used too.
These influences would be smaller at longer range (150-200 y).

While ammo transitioning through the transonic zone does have an effect on accuracy/consistency, it doesn't affect 22lr enough to really matter. I rarely deal with 22lr in the transonic zone, I normally shoot target or match grade ammo that is subsonic from the muzzle when accuracy is the goal. When I do shoot HV ammo it is usually at BIG targets well inside the transonic zone (40 yards or less).

As for "Drops up to 75 yards or so are more sensitive to MVs than to BC figure." The BC directly impacts velocity from the time the projectile leaves the muzzle, so it still plays a part in drops at closer ranges, including 75 yards and closer.

 

[bulletbluesky]

As for "Drops up to 75 yards or so are more sensitive to MVs than to BC figure." The BC directly impacts velocity from the time the projectile leaves the muzzle, so it still plays a part in drops at closer ranges, including 75 yards and closer.

Normally BC always impacts the drop, but at closer ranges constancy of MV and BC impacts accuracy even more (among other things)
BTW, this kind of radar seems suitable to me for the measurements:
https://www.pyramydair.com/product/fx-outdoors-true-ballistics-chronograph?a=13379

 

[WittyWook]

I was watching an MDT video on this just the other day. One suggestion they had to keep groups small is to move your point of aim from point of impact. If you loose your point of aim due to shooting it out, your groups will naturally widen out. Try adjusting your scope a few tenths one way or another to get that consistent point of aim and see if that tightens the groupings.

 

[grauhanen]

With the same varieties of .22LR match ammo up to 100 yards or so, minor variations in BC won't make any meaningful difference in accuracy performance. Especially at distances beyond 50 yards, MV variation will play a bigger and bigger role. So, too, will variation in Cg from round-to-round and lot-to-lot.