PCC zero - What Yard Zero?

[Stephen7942]

Getting my new JP GMR-15 in pretty soon. I am going to put a trijicon MRO on top. What are your recommendations for how many yards to zero the carbine at for USPSA?

 

I was thinking 25 yards and then check holdover differences for anywhere from 5-50 yards in 10 or so yard increments.

 

thanks in advance for any advice!

 

-SS 

[S&W686]

I personally zero mine in at 15yds, but many of the other PCC shooters at our club zero theirs at 25 yards.

[ChuckS]

25 minutes ago, Stephen7942 said:

Getting my new JP GMR-15 in pretty soon. I am going to put a trijicon MRO on top. What are your recommendations for how many yards to zero the carbine at for USPSA?

 

I was thinking 25 yards and then check holdover differences for anywhere from 5-50 yards in 10 or so yard increments.

 

thanks in advance for any advice!

 

-SS 

here some earlier threads:

(The search function is your friend )

[Stephen7942]

Thanks for those links! Should have searched first lol! Got some reading to do now!!

[LowSpeedHighDrag]

I've switched from a 25 yard zero to a 10 yard one.  It best matches the kind of distances I usually run into at local matches, and makes the closer targets easier to shoot quickly.  Probably not a good idea if you need to go out to 100 yards - don't even know (or have bothered to test) what that would require for compensation.

[36873687]

15 yards has worked for me

[assaultthesalt]

15 yards , here.

[nick954]

15yrd, but i haven't shot it in a match yet. I have a 6moa vortex venom offset at 7rds just in case I have some stage required head shots.

[MoRivera]

Also 15 yds here.  That's usually the max distance when shooting local matches or plates/steel.  Sometimes there are longer shots but I hold a little low and it's always a bit slower of a shot anyway.

[cecil]

12 yards...  at 15 yds no adjustment is required.. 

[Manwithnoname]

13 minutes ago, cecil said:

12 yards...  at 15 yds no adjustment is required.. 

12 yards too. 

[JsK]

25 yards. All shots inside 15 will require a hold over but that's it. With a short 12-15 yard zero you have to remember both a hold over up close and to hold lower at 25 yards. The short zeros get even worse the further you go out, at 100 yards its shooting like 3ft high.

[SwedishMoose]

4 hours ago, JsK said:

25 yards. All shots inside 15 will require a hold over but that's it. With a short 12-15 yard zero you have to remember both a hold over up close and to hold lower at 25 yards. The short zeros get even worse the further you go out, at 100 yards its shooting like 3ft high.

 

I think it also depends on which sport you're shooting. 3 feet high at 100 is fine for people who shoot USPSA who are never shooting more than ~25 yards in a given stage. 

[Bwillis]

75 feet

[onlyupfromhere]

25yd zero, and then I check out at 11yd then 50/75/ 100yds and on steel at 200. I rarely shoot USPSA with it, the big PCC comp out here will have targets around 180-200yds.

[JsK]

5 hours ago, SwedishMoose said:

 

I think it also depends on which sport you're shooting. 3 feet high at 100 is fine for people who shoot USPSA who are never shooting more than ~25 yards in a given stage. 

I think the point your missing is it's one adjustment and that's about 2.5" high from point blank out to about 15 yards after that it shoots to point of aim and has the natural expected hold over at 100yards. Short zeros require you to hold high up close(7 yards and closer) and the require you to hold low on already difficult 25yrd shots.25yrd is just easier.

Edited February 14, 2020 by JsK

[ck1]

10 hours ago, JsK said:

25 yards. All shots inside 15 will require a hold over but that's it. With a short 12-15 yard zero you have to remember both a hold over up close and to hold lower at 25 yards. The short zeros get even worse the further you go out, at 100 yards its shooting like 3ft high.

 

IDK mang.

 

 Zero wherever you want as long as you know your hold over/under's with your gun/ammo... it's just personal preference and remembering not to forget about your sight-over-bore distance. Personally, for USPSA, I run a 15yrd zero because on most stages the majority of targets are going to be bewteen 7-20yrds, and a 15yrd zero puts me at just about an inch low at 7 and an inch high at 25 with my setup (-/+ 1.3" to be exact), so I don't really need to think about it much as long as I do my part. YMMV. 

 

That said, IDK where you're getting "3ft high at 100"..? My gun/ammo setup with the same 15yrd zero puts me only 1.2" high @ 100yrds. The bullet does start to drop quickly beyond that though, so I would be about 2.5ft low @ 200yrds, one hell of a holdover (but still probably a doable morter-shot on a man-sized steel plate with a few tries lol).

I don't reload like most around here, mostly shoot the Federal Syntech USPSA/PCC-specific stuff at matches (130gr 1140fps, 148pf out of a 16" barrel supposedly), which is still soft AF out of my MPX, but probably a bit hotter than some. Even if one was scraping the power-floor (say130-133pf) with a 15yrd zero they'd still only be just over an inch low/high @ 7 and 25, 2.5" or so low at 100yrds.

 

http://gundata.org/ballistic-calculator/

[JsK]

11 minutes ago, ck1 said:

 

IDK mang.

 

 Zero wherever you want as long as you know your hold over/under's with your gun/ammo... it's just personal preference and remembering not to forget about your sight-over-bore distance. Personally, for USPSA, I run a 15yrd zero because on most stages the majority of targets are going to be bewteen 7-20yrds, and a 15yrd zero puts me at just about an inch low at 7 and an inch high at 25 with my setup (-/+ 1.3" to be exact), so I don't really need to think about it much as long as I do my part. YMMV. 

 

That said, IDK where you're getting "3ft high at 100"..? My gun/ammo setup with the same 15yrd zero puts me only 1.2" high @ 100yrds. The bullet does start to drop quickly beyond that though, so I would be about 2.5ft low @ 200yrds, one hell of a holdover (but still probably a doable morter-shot on a man-sized steel plate with a few tries lol).

I don't reload like most around here, mostly shoot the Federal Syntech USPSA/PCC-specific stuff at matches (130gr 1140fps, 148pf out of a 16" barrel supposedly), which is still soft AF out of my MPX, but probably a bit hotter than some. Even if one was scraping the power-floor (say130-133pf) with a 15yrd zero they'd still only be just over an inch low/high @ 7 and 25, 2.5" or so low at 100yrds.

 

http://gundata.org/ballistic-calculator/

Have you actually tried it or are you just quoting a balistic program?  

[ck1]

19 minutes ago, JsK said:

Have you actually tried it or are you just quoting a balistic program?  

 

Rang steel at 100 a few times for fun, just aimed and heard "ping" didn't even think about it.

[JsK]

My wife shoots both USPSA and 3gun with her pcc. Like alot of people I started with the short 10-15 yard zeros but with the 2.75 to 3" height over bore you have to crank the dot down so far that its shooting 8" to a foot low at 50 - 100yrds. Considering this is a common engagement distance we changed her over to a 25yrd zero and I switched my pcc shortly after. Yes 3ft is an exaggeration but running our 3gun club i have seen many guns shoot so high at 100 yards the aiming at the bottom of plate rack. Everything we had learned was confirmed when we took maxs class. Sure you can zero at any distance and memorize your holdovers its entirely possible but is it practicle.or the most efficient? 

[Sean_ht]

I have the exact same setup, MPX with MRO.

I zero at 20 yard. It covers any distance between 10 and 30 yards.

• For a close range target, either I aim at the top of the A-zone (body), or top of the cardboard for the head-shot's A-zone (there is 1" gap between the top of the cardboard and top of the A-zone).
• As for a long range shooting, it completely depends on your ammo. You need to calculate the trajectory for your choice of ammo, and memorize the drop at the reference distances (100, 150, 200, ...).

 

I am right now thinking about adding a 45-degree red-dot for a close range shots. Not yet convinced that it really has any advantage over the single red-dot system & simply remember the hold-overs for the close-range shots. Saying that, it is more about the aesthetic than practicality.

Edited February 14, 2020 by Sean_ht

[ck1]

1 hour ago, JsK said:

My wife shoots both USPSA and 3gun with her pcc. Like alot of people I started with the short 10-15 yard zeros but with the 2.75 to 3" height over bore you have to crank the dot down so far that its shooting 8" to a foot low at 50 - 100yrds. Considering this is a common engagement distance we changed her over to a 25yrd zero and I switched my pcc shortly after. Yes 3ft is an exaggeration but running our 3gun club i have seen many guns shoot so high at 100 yards the aiming at the bottom of plate rack. Everything we had learned was confirmed when we took maxs class. Sure you can zero at any distance and memorize your holdovers its entirely possible but is it practicle.or the most efficient? 

 

I'm not trying to be snarky or argumentative here, but I was having trouble grasping the phenomenon you're describing with 9mm rounds shooting so high at 100yrds that one would have to hold at the bottom of a plate rack (say 3 feet-ish low) to hit a plate... because well, physics. 

 

I think I get what you mean by "crank the dot down" (i.e. dialing elevation to bring the POI up/down to match POA, hit "x" when aiming at "x"), but since height-over-bore is taken out of the equation once set at a given zero distance, that really shouldn't have anything to do with anything... and since trajectory is trajectory and ballistics is ballistics, and we know what an average 9mm round is going to basically do trajectory/ballistics-wise: the only explanation for what you're describing is zeroing at like 5yrds, not 10-15.

In fact, with my load, if I zeroed at 5yrds I'd be 34" high at 100. 

 

I'm not debating what's the most practical or efficient zero, because I don't think there is one; it's up to the individual and one's own personal preference. Of course one could argue that a 25yrd zero is best, but only if that individual doesn't mind printing low and having a hold-over on everything out to 25. To each his own. But one preferring a closer zero in order to not always have a hold-over to factor and usually be between 2 inches up/down on the majority of targets isn't wrong either. 

 

 

 

[JsK]

46 minutes ago, ck1 said:

 

I'm not trying to be snarky or argumentative here, but I was having trouble grasping the phenomenon you're describing with 9mm rounds shooting so high at 100yrds that one would have to hold at the bottom of a plate rack (say 3 feet-ish low) to hit a plate... because well, physics. 

 

I think I get what you mean by "crank the dot down" (i.e. dialing elevation to bring the POI up/down to match POA, hit "x" when aiming at "x"), but since height-over-bore is taken out of the equation once set at a given zero distance, that really shouldn't have anything to do with anything... and since trajectory is trajectory and ballistics is ballistics, and we know what an average 9mm round is going to basically do trajectory/ballistics-wise: the only explanation for what you're describing is zeroing at like 5yrds, not 10-15.

In fact, with my load, if I zeroed at 5yrds I'd be 34" high at 100. 

 

I'm not debating what's the most practical or efficient zero, because I don't think there is one; it's up to the individual and one's own personal preference. Of course one could argue that a 25yrd zero is best, but only if that individual doesn't mind printing low and having a hold-over on everything out to 25. To each his own. But one preferring a closer zero in order to not always have a hold-over to factor and usually be between 2 inches up/down on the majority of targets isn't wrong either. 

 

 

 

So again I am asking have you actually checked your zero at these ranges and what are you using as a bore height offset in your ballistics program? Your talking theory and I shoot both at 25 , 50 and 100 every time I check the zero because of what disciplines we use them for. As I said 3ft was an exaggeration but 20-24"high is not unusual with really short zeros.

If you dont understand how much difference height over bore makes in the trajectory past your initial zero than I think that's our disconnect.

[JsK]

So let's move past long range for a minute since that's obviously a different discussion .

 

So here is a plot for a 15yrd zero. Assuming we are aiming for the 2" head box you would need multiple different holds inside 15 yards as no single aiming point keeps the standard 7- 10- 15 yard shots inside the head box. 

 

Move past 15 and it's the same out to 25. Multiple different holds to stay within  2" head box

[JsK]

By contrast holding at the top perf gives hits from 7 -10-15 with a single hold with a 25yrd zero. Move out past 15 and it's all center eye box holds and A hits. 

 

Pcc hit factor should be somewhere between 6-9 for the average shooter so even a half second pause negates a double alpha. At that point you might as well just throw 2 Charlie's fast and move on. If you can get fast As on difficult head box targets it goes along way toward winning.

Edited February 15, 2020 by JsK