SK Standard+ & Rifle Match Drop Variance?

[Precision Catharsis]

Disclaimers/info:

1. I'm new to precision shooting
2. I have a CZ 457 Pro Varmint w/ an Athlon Optics Argos BTR Gen2 6-24X50
3. I've been ammo testing (5 shot groups) off a sled at a range w/ solid benches and tall earthen wind barriers (I still only test when there's barely any wind)
4. I use the Range Buddy app to measure my groups

The other day I was trying some SK ammo at 50 & 100yds. As I understand it, SK Standard + and SK Rifle Match are basically the same ammo but I should essentially expect tighter SD/performance from runs they labeled Rifle Match. On SK's site, all the ballistic data for both types are spot on the same. Hence, while I assumed the Match would likely get tighter groups (unless I really lucked out on the S+ lot), I also assumed the avg POI and drop and such would remain the same between the two types, or at least be extremely close and only exhibit the same type of minimal changes you might notice from lot to lot.

After shooting four 5-shot groups of each at 50 yards and the same at 100 yards, I noticed the following:

• On average, the Rifle Match groups' POI was only 0.1" higher than Standard+'s at 50 yds, but a full 1.1" higher than Standard+'s at 100yds. (And it wasn't just the POI's average either, as the POI difference between ammo types was fairly consistent each time. At 100 yds, there was only about a 0.1" POI variation between each group of the same ammo type.)

This surprised me, as I was hoping I could use these two ammo types interchangeably but basically rely on the same DOPE. Should this difference actually surprise me though, or is that kind of variation to be expected between lots of ammo from a brand like SK?

For both the Standard + and Rifle Match, SK's site lists a 7" drop at 100yds if you're zeroed at 50yds (like I was.) The Standard + drop was almost exactly that at just a sniff over 7". Do the math then... the Rifle Match was around only a 6" drop. Hmm...

I also find it really strange that the POI drop gap wasn't really there at 50 yards, but became super apparent at 100 yards. That doesn't make sense to my brain.

Finally, I'll throw in here that although I'm fairly new, I feel like I'm a decent enough shooter simply because there isn't much variance in my groups' sizes and POI for each ammo I test, and I've shot a few hundred rounds through this thing by now as I've tested around 6 ammo types so far. (By the way, had some great success with SK Flatnose Match. In fact, the 2nd time I took my rifle out, I pulled off a 0.12" CTC group at 50yds. My avg of 6 groups with that stuff was right around 1/2 MOA. I'm happy with that!)

Anyway, just hoping someone with way more knowledge than me could possibly chime in and educate me. Maybe my expectations are off. Maybe it's me. Thanks!

 

[DrDWD]

Do you have a good muzzle velocity measurement with both in your rifle?

Was the temperature the same for both? I saw some velocity drops with the SK Std+ and RM above and below about 60F.

 

[Precision Catharsis]

Good questions.

I don't have MV measurements and I had not planned to invest in a chronograph any time soon unfortunately. I would have to assume, given the results, there's some MV variance there between my box of Standard+ and Rifle Match. My main questions then are basically: Why? Would a difference of this size at 100 yds not be all that unexpected or does it sound a bit odd? And why is the gap not very apparent at 50yds but much more obvious at 100yds... is there something to the math I don't understand? I mean... I know it's not quite this simple, but I guess if I'm seeing about a 1" difference at 100yds, I might have seen a 1/2" difference at 50yds.

I shot both sets of groups during the same outing one right after the other, so the temp was the same: in the low 70s (F). Barely any wind at all.

 

[KnowNothing256]

Could be that a minor difference in MV is resulting in a good-sized difference in harmonics at the moment the bullet clears the muzzle.

But fundamentally, it just sounds like you have two different DOPEs. Not terribly uncommon in LR 22LR, even just lot-to-lot variances.

 

[Precision Catharsis]

Could be that a minor difference in MV is resulting in a good-sized difference in harmonics at the moment the bullet clears the muzzle.

But fundamentally, it just sounds like you have two different DOPEs. Not terribly uncommon in LR 22LR, even just lot-to-lot variances.

If true, that is both relieving and frustrating to hear Relieving to know I'm not necessarily such a horrible shooter I'm doing something to cause huge variance in my groups. Frustrating to hear that once I come up with a DOPE, the next lot could be totally different if MV differs that much from lot to lot.

 

[ballisticdaddy]

The rimfire data listed on the box is an average velocity, not necessarily the exact speed of your ammunition. Sounds like you may have got a lot of Rifle Match that is a bit faster than the box of Standard +. If these differences are enough to frustrate you then you might want to get a good chronograph and chart the velocities. Even different lots within the same brand have noticeable differences. Rimfire ammo is very finicky and once you find a lot your rifle like, buy a truckload of it

SK Rifle & LR Match Velocities

This is the first time I have done any muzzle velocity testing for rimfire, was testing my CF loads so figured WTF and wanted to share. This was all done today using a LabRadar for velocities through a Vudoo with Ace / Kukri contour 16.5" barrel with just a thread protector. Was surprised at...

www.snipershide.com

 

[Precision Catharsis]

The rimfire data listed on the box is an average velocity, not necessarily the exact speed of your ammunition. Sounds like you may have got a lot of Rifle Match that is a bit faster than the box of Standard +. If these differences are enough to frustrate you then you might want to get a good chronograph and chart the velocities. Even different lots within the same brand have noticeable differences. Rimfire ammo is very finicky and once you find a lot your rifle like, buy a truckload of it

SK Rifle & LR Match Velocities

This is the first time I have done any muzzle velocity testing for rimfire, was testing my CF loads so figured WTF and wanted to share. This was all done today using a LabRadar for velocities through a Vudoo with Ace / Kukri contour 16.5" barrel with just a thread protector. Was surprised at...

www.snipershide.com

This was the only explanation that made sense to me and I just didn't know how plausible it was or how common. In my particular case it would mean my lot of S+ is very close to SK's listed avg ballistic data, and my box of Match was hotter than normal. This seemed backwards to my brain, as I thought perhaps lots labeled Match would have tighter restrictions on lot to lot variation than say S+, but maybe that's not true and it's just tighter SD/tolerances within each lot itself. (In that way, I would consider lots of RM to be more like Single Barrel whiskey... typically a better bottling of itself, but perhaps different from batch to batch? )

Ammo testing itself is fun, but if there's that much variance between the same ammo (and for all intents and purposes, I'm considering S+ and RM "the same" ammo) it also feels a bit like an exercise in futility unless you're prepared and able to buy larger quantities like you say. I live near the Lapua testing center in Ohio so was thinking of doing that just to get something that shoots great and has a repeatable DOPE, but the minimum buy of a case of 5k is a bit much for my wallet at the moment. (I'm not even sure if they'd be able to fulfill orders right now anyway.)

 

[KnowNothing256]

Buying a large quantity of a single well-performing lot is the tried-and-true method of maximizing 22LR consistency; time and again, folks have found ammo variability to be the hardest aspect of overall 22LR precision to control.

In today's ammo shortage climate, the Lapua Testing Center is the only reliable method I know of to get a bunch of a proven-to-perform lot, so I’d recommend saving up for a batch. I just wish they’d test SK lots too...

 

[DFOOSKING]

I've ran 4 bricks of yellow this season and handful of boxes of other stuff. First brick averaged 1175fps in my Bergara. The last two bricks averaged 1121fps.

I treat every brick unless it has the same lot #.....as its own animal and needing verification.

 

[justin amateur]

I treat every box, even if it has the same lot #,.....as its own animal and needing verification

Fixed it.

The only way I can ensure it's not me, is by using a ballistic chronograph every trip to the range.
This is mass produced ammunition. All it takes is a minor slip in tolerances on the assembly line,
a change in powder/primer chemistry, crimp, seating, temperature or humidity and you end up with mv variations.

 

[Precision Catharsis]

I've ran 4 bricks of yellow this season and handful of boxes of other stuff. First brick averaged 1175fps in my Bergara. The last two bricks averaged 1121fps.

I treat every brick unless it has the same lot #.....as its own animal and needing verification.

Ahh interesting. Thanks for the real-world use case. With a difference of 54fps avg between those lots, what sort of difference in drop do you think that would make at some given distance (say 100 yds? )

 

[grauhanen]

As noted by others, the MV rating of any .22LR ammo is not something that is reliably accurate. MV ratings are the average MV and nothing more. MV will vary from round to round in a box of ammo. Each lot can have a different average. It's impossible at anything near a reasonable cost to make .22LR ammo with identical MVs.

To illustrate, with Lapua .22LR ammo, the factory obtained average in the factory test barrels can be determined by adding the number 3 to the first two digits of the lot number to produce the average MV in m/s. The first two digits of Lapua ammo Eley ammo used to be sold with the lot average printed on the label of the ammo box (perhaps it still is, but I'm not sure as I haven't bought new Eley in a few years). I don't know if SK ammo lot numbers can be used to determine the average MV of each lot.

Another important factor to keep in mind is that the same ammo can have different MVs in different rifles, even those of the same make and model with barrels that are of equal length.

No one can know for sure what the MV of the ammo actually is unless it's chronographed.

 

[Precision Catharsis]

Thanks grauhanen for reiterating. I'm not shooting out of different rifles - for now just the one. And I certainly understand there's difference between rounds and what to, generally speaking, expect in terms of SD from the same box of these ammo types.

With all that in mind, my main concern wasn't whether or not MV would match stated averages from the manufacturer per se. Overall what I was trying to get to here was what kind of avg MV variance is common from lot to lot (or at least within the realm of "plausible" from a manufacturer like SK), and how much such a plausible variance could effect drop in the real world.

In other words: is the 1" difference in POI I noticed at 100yds plausibly caused from what's been discussed as a lot-to-lot avg MV variance, or something else entirely. I'm still trying to understand this one point and feel like I'm almost there. DFOOSKING mentioned seeing a 54fps avg variance from lot to lot in S+ (so there's a starting point to plausibility range), but I guess I'm not sure how such a delta would effect actual drop because, well... because I'm so green!

 

[justin amateur]

At 100 yards, 40 fps difference in mv will produce about 1 inch of vertical spread.
That's with 40 grain match quality 22lr. With low quality cartridges, no telling how it will affect spread.

Ballistic Calculator GunData.org

Give this ballistic program a try. Web based, free, fairly accurate for my needs.
Set the zero distance to 0, calculate with 2 bullets with different mvs and compare results.

 

[KnowNothing256]

At 100 yards, 40 fps difference in mv will produce about 1 inch of vertical spread.
That's with 40 grain match quality 22lr. With low quality cartridges, no telling how it will affect spread.

Ballistic Calculator GunData.org

Give this ballistic program a try. Web based, free, fairly accurate for my needs.
Set the zero distance to 0, calculate with 2 bullets with different mvs and compare results.

Used a similar method in the Hornady 4DOF for my SK Std+ profile, but used a 21-yd zero because the 50-yd preset was adjusting for the 56 FPS change too much. The 0-yd zero method works great as long as you use a scope height of zero as well.

OP, my test showed a 1.3” change from 1066 to 1010 FPS, using a 21-yd zero. This jives well with @justin amateur ’s info. So yes, that’d account for your vert spread.

 

[Precision Catharsis]

AWESOME! Thanks crew, this was a super helpful lesson.

 

[DFOOSKING]

Thanks grauhanen for reiterating. I'm not shooting out of different rifles - for now just the one. And I certainly understand there's difference between rounds and what to, generally speaking, expect in terms of SD from the same box of these ammo types.

With all that in mind, my main concern wasn't whether or not MV would match stated averages from the manufacturer per se. Overall what I was trying to get to here was what kind of avg MV variance is common from lot to lot (or at least within the realm of "plausible" from a manufacturer like SK), and how much such a plausible variance could effect drop in the real world.

In other words: is the 1" difference in POI I noticed at 100yds plausibly caused from what's been discussed as a lot-to-lot avg MV variance, or something else entirely. I'm still trying to understand this one point and feel like I'm almost there. DFOOSKING mentioned seeing a 54fps avg variance from lot to lot in S+ (so there's a starting point to plausibility range), but I guess I'm not sure how such a delta would effect actual drop because, well... because I'm so green!

Drop was 1.6 @ 100yds.

Next brick it was solid 1.8 @ 100yds.

Solid dope rules all.

Just finished pissing the NRL22 Nat's away. Scope was thwacking plates like its cool for 4 stages. First stage went out to 350yds. Got a 9/10. Next three stages were troop lines and a tank trap stage. Did really good. Then my scope stopped tracking for the next 4 stages and destroyed any hopes of a Top 25 finish (my personal goal). Ran a snake through and gave a quick smack to the elevation turret. Finished the last stage of Day 1 almost cleaning the 2nd longest range stage.

Day 2 was better but not enough. My squad did great though...especially for their first ever National Match.

Managed to get a couple of shirts and some stickers for my efforts. Oh well...maybe next year.

 

[Precision Catharsis]

Drop was 1.6 @ 100yds.

Next brick it was solid 1.8 @ 100yds.

Solid dope rules all.

That's interesting, even with a 54fps avg variance you're only seeing a difference of about 1/5" at 100yds huh?

justin amateur: Messing around with the ballistic calc at GunData.org, I'm not seeing a 1" drop for 40fps difference between two bullets either. I'm not sure if I'm doing something wrong but, trying a bunch of different settings, it seems like you need at least 100fps difference to see that sort of variation at 100yds.

I think my 1" POI difference remains a mystery, unless SK really screwed up and my box of Rifle Match was just really, really hot.

 

[KnowNothing256]

That's interesting, even with a 54fps avg variance you're only seeing a different of about 1/5" at 100yds huh?

justin amateur: Messing around with the ballistic calc at GunData.org, I'm not seeing a 1" drop for 40fps difference between two bullets either. More like 1/2".

I think my 1" POI difference remains a mystery, unless SK really screwed up and my box of Rifle Match was just really, really hot.

Is the 1/2” difference you’re seeing with a 50yd zero? The reason this matters is that the ballistics of 22LR are so slow (lots of drop) that if you zeroed at 50 yds, then dropped 56 FPS, you’d have to adjust your zero up. If you leave the 50 yd zero in the program, it’s essentially baking that “pre-drop” into your solution and hiding it from you.

Set the scope height to zero and the zero range to zero, then run the numbers.

 

[KnowNothing256]

Actually, I did it for you, here ya go. CCI SV, 1066 vs 1010 FPS, zero sight-over-bore, zeroed at zero yards.

 

[justin amateur]

KnowNothin' has it correct.
If you had zero set at 50 yards, you took out half the drop by doing so.
You end up calculating the drop from 50 to 100 yards.

Another method is to set the zero at double the distance y'er shooting
then compare the results at the mid point of the trajectories.
Zero at 200 yards, compare trajectory difference at 100 yards.
Produces a similar answer.

 

[DFOOSKING]

That's interesting, even with a 54fps avg variance you're only seeing a difference of about 1/5" at 100yds huh?

No....not 1/5"

.2 mil or .72" @ 100yds.

You won't likely hit a 1" target being that far off when you start factoring in things like stress, position, movement and time starting to open your groups up.

 

[Precision Catharsis]

Brilliant, I'm back on track. All makes sense.

 

[bwall57]

Good questions.

I don't have MV measurements and I had not planned to invest in a chronograph any time soon unfortunately. I would have to assume, given the results, there's some MV variance there between my box of Standard+ and Rifle Match. My main questions then are basically: Why? Would a difference of this size at 100 yds not be all that unexpected or does it sound a bit odd? And why is the gap not very apparent at 50yds but much more obvious at 100yds... is there something to the math I don't understand? I mean... I know it's not quite this simple, but I guess if I'm seeing about a 1" difference at 100yds, I might have seen a 1/2" difference at 50yds.

I shot both sets of groups during the same outing one right after the other, so the temp was the same: in the low 70s (F). Barely any wind at all.

Use a chronograph to track your data against the environmentals. The answer is in the wind and the amount of error caused by Scope cant. A smiple solution would be to use LRA MV3 "e" level to help to eliminate one more of the variables. It's similar to having a FFP scope with good parallax adjustment to improve your POI by improving your POA consistency. Seeing the FPS & SD with the wind flags will instantly tell you what is going on and make you a better shooter. Knowing the SD is key in determining ammo performance for every shot. The old scope bubble level tolerances are sloppy and takes you off the reticle at trigger time. Have fun and good luck with the head winds!

 

[skyrep]

I’ve found that testing velocity at different temps give me different MV. Enough difference in velocity that when I am shooting a Match, I check the temp every half hour. I have put the MV in StrelokPro APP with each MV at certain temps and has helped me out with getting the correct dope for that temp. at that time of shooting. Ammo tested with same lot number.

SK long Rang Match: MV/SD

45 degrees - 1095/7.3

56 degrees - 1112/5.0

68 degrees – 1123/3.3

 

[bwall57]

Good questions.

I don't have MV measurements and I had not planned to invest in a chronograph any time soon unfortunately. I would have to assume, given the results, there's some MV variance there between my box of Standard+ and Rifle Match. My main questions then are basically: Why? Would a difference of this size at 100 yds not be all that unexpected or does it sound a bit odd? And why is the gap not very apparent at 50yds but much more obvious at 100yds... is there something to the math I don't understand? I mean... I know it's not quite this simple, but I guess if I'm seeing about a 1" difference at 100yds, I might have seen a 1/2" difference at 50yds.

I shot both sets of groups during the same outing one right after the other, so the temp was the same: in the low 70s (F). Barely any wind at all.

No chronograph = No idea what you are shooting = Clueless. A good idea would be to use some wind flags to improve the group sizes, it should help in guessing where the POI is. Very good analysis of your unexpected Probability of Random POI targeting using no environmental conditions. Very interesting. Keep up the good work and have fun. We are all learning how to shoot 22lr and find that the FPS on the box fancy box is useless for your rifle on the day you are shooting. With good FPS, SD and ballistic data entered into a Strelok or other ballistic calculator that will answer many of the performance and accuracy questions with numbers. The numbers really work, its rewarding to dial in an MOA / MIL elevation and hold and hit the POA=POI the first time. It makes me smile every time. With the right tools you will find the answer too. Try it. Its a wind game.

 

[KnowNothing256]

No chronograph = No idea what you are shooting = Clueless. A good idea would be to use some wind flags to improve the group sizes, it should help in guessing where the POI is. Very good analysis of your unexpected Probability of Random POI targeting using no environmental conditions. Very interesting. Keep up the good work and have fun. We are all learning how to shoot 22lr and find that the FPS on the box fancy box is useless for your rifle on the day you are shooting. With good FPS, SD and ballistic data entered into a Strelok or other ballistic calculator that will answer many of the performance and accuracy questions with numbers. The numbers really work, its rewarding to dial in an MOA / MIL elevation and hold and hit the POA=POI the first time. It makes me smile every time. With the right tools you will find the answer too. Try it. Its a wind game.

I would actually submit that you don't need a chrono, if you have decent drop data at multiple ranges. If you zero at 50, and then can get dope at 75, 100, 125, and 150 yards, you should be able to get a solid MV and BC estimate. I'd grab a general BC (Sk Std+ in my Vudoo is 0.120 G1, Sk Std+ in my CZ 455 is 0.125 G1, and CCI Std in my CZ 455 is 0.115 G1, so I'd just start with 0.120 G1), then see what MV in your calculator lines up with your real-world dope.

You do need to feed the calculator good environmental data for this to work, but I think you'll find that 100 yards is plenty to true your MV. If you can't get your dope at 75 yds and 100 yds to match, fiddle with the BC, then really true it up at 125 or 150 yards.

I don't chrono my 22LR anymore; I have a MagnetoSpeed and it works just fine, but I find it's not really necessary. I don't really use the chrono on my centerfire either; maybe for load development to see generally where I'm at, but I just shot a club match this weekend, and I just used a plate at 600 yds to verify my MV in significantly different atmospherics than where I zeroed. Worked out fine.

ETA: I should've checked the dates on this thread before replying. Looks to me like the OP got squared away like 9 months ago...

 

[bwall57]

I would actually submit that you don't need a chrono, if you have decent drop data at multiple ranges. If you zero at 50, and then can get dope at 75, 100, 125, and 150 yards, you should be able to get a solid MV and BC estimate. I'd grab a general BC (Sk Std+ in my Vudoo is 0.120 G1, Sk Std+ in my CZ 455 is 0.125 G1, and CCI Std in my CZ 455 is 0.115 G1, so I'd just start with 0.120 G1), then see what MV in your calculator lines up with your real-world dope.

You do need to feed the calculator good environmental data for this to work, but I think you'll find that 100 yards is plenty to true your MV. If you can't get your dope at 75 yds and 100 yds to match, fiddle with the BC, then really true it up at 125 or 150 yards.

I don't chrono my 22LR anymore; I have a MagnetoSpeed and it works just fine, but I find it's not really necessary. I don't really use the chrono on my centerfire either; maybe for load development to see generally where I'm at, but I just shot a club match this weekend, and I just used a plate at 600 yds to verify my MV in significantly different atmospherics than where I zeroed. Worked out fine.

ETA: I should've checked the dates on this thread before replying. Looks to me like the OP got squared away like 9 months ago...

Mission accomplished, at least you spent time to responding. Good job . I see that you have some knowledge on running a ballistic calculator. The point was to state that the quality of 22LR is not consistent and is missed by many who keep chasing expensive top tier ammo and have no idea why they have poor POI performance. I understand your comments and have the tools such as magneto speed (which is a chronograph), Lab radar.DXL chronograph and kestrel 5700 ballistic calculator to work with the data and get result. Most of the stuff on the video web is pure entertainment trying to sell you something with no technical data. I enjoyed your analysis. Good information is timeless. Have fun playing with the BC.

Keep it clean to keep to keep it shooting straight.