Sighting in a pistol: ammo dependent?

[DreadPirateMoyer]

I ask because my carry ammo is expensive (Federal HST 147 grain) and I can't precisely adjust my sights (they don't fit properly in my sight adjuster). This means I have to sight in with a mallet and drift punch, which is very unprecise and is more trial-and-error than anything. I'd prefer to avoid shelling out a ton of money for carry ammo, only to blow it sighting in at the range.

Would I be safe using FMJ from a trusted brand for sight in? I've seen some wonky pictures on here and other forums regarding ammo, including windage drifts on non-windy days with different grain types (I don't get how that happens), so I thought I'd ask.

P.S.: not concerned with elevation; only windage.

[A62Rambler]

eIn theory Every load shoots differently. Even different lots of the same brand ammo can shoot differently. Having said that, I would use a load with the same weight bullet at roughly the same velocity to sight it in. Then test with you duty ammo. If it is off more than you like adjust again with your practice load moving the group in relation to what your duty load needed to move. Then reconfirm with duty ammo. If that made sense. In reality you may find that there isn't enough difference to matter. ;)

[DreadPirateMoyer]

Makes perfect sense. I think that's what I'll do.

Thank you very much. :)

[DreadPirateMoyer]

Come to think of it, a second question:

I know when sighting in rifles/testing for accuracy, 10-shot groups are the standard. Are 10-shot groups recommended for pistols as well?

[DreadPirateMoyer]

Welp, bought some AE 147 grain 9mm. Hope it performs similarly since they're from the same company and are both 147 grain.

[ST911]

What manufacturer/model of gun?

Sights?

Is this question theoretical, or have you actually fired the gun and determined your sights are off?

At what distance, and to what extent are you having those deviations?

Are you a shooter of sufficient ability to consistently produce these deviations?

[CAVDOC]

I suspect you are doing lateral adjustment for windage . In that case windage zero tends to vary little between bullet weights. You could start with 115 grain then confirm with 147. If you are try to do something with sight height/ elevation the. Bullet weight will make a difference

[JSantoro]

I know when sighting in rifles/testing for accuracy, 10-shot groups are the standard.

Think of it as less of a "standard," and more of providing a better sample size with which to tell how the thing actually prints. 10 rounds will "fill in the circle" better than 3 or 5; provided you shoot consistently for each round, more rounds provides a more complete pattern. How many rounds that may be is up to the shooter, and 10 is a nice round number that gives a solid baseline upon which to measure.

The only way to truly know how your carry ammo prints is to use your carry ammo to find out. Anything else is going to be a best guess, though it's possible to make a fairly highly informed guess. It'll still be a guess, though, so the question becomes whether or not that guess is highly informed enough for your own peace of mind.

Consider, also, using mean radius to judge your groupings, instead of the extreme-spread that's so much more commonly tossed about when folks talk about these things. It's more time-consuming than simply throwing a ruler across a group, but it's also gonna provide better data, especially if you're gonna be moving sights about.

https://www.m4carbine.net/showthread.php?t=64906

It's also called ATC, or Average To Center.

[DreadPirateMoyer]

Yup, lateral adjustments. Good to hear that doesn't change much with grains. Hopefully this AE 147 grain mimics my carry load. :)

For Skintop: Glock, 10-8 sights, actually off, all distances (will be sighting in at a minimum of 15 yards, though), and yes. Babam!

10-round groups for sight in? Or can you accurately sight in with less since this isn't as precise a game as rifle shooting? Or does it need more?

[jmnielsen]

I've always done 3 rd groups for my rifles. I'd would say 5 for pistol would be fine. Assuming its not a competition gun that needs to be extremely accurate.

[DreadPirateMoyer]

Whoa, my reply must've happened simultaneously with J's on my end.

That was really informative. Thank you!

And I'll let you know how it all goes since you've all provided so much help. Hopefully it works out!

[A62Rambler]

I used to shoot rifles really well when I shot daily and used three shot groups (cloverleafs). Now I use 10 shot rifle groups. I've never been a good pistols shot so I've always used 10 shot groups with pistol or revolver. As one instructor noted, you shoot patterns not groups. :eek: Actually, he asked what kind of shotgun I was using at a pistol qualification. Ouch! Anyway, it will depend on how well you shoot to answer your question. :D

[CAVDOC]

as far as number of rounds fired that would have to depend on what level of accuracy YOU are capable of- my personal opinion using 10 yards as an example at that distance your group size (regardless of where the group is on paper) should be less than two inches. if it is not you are making fundamental errors in technique (grip stance trigger control sight alignment) andf trying to chase a zero at that time is pointless. if you can fire a five shot say 1.5 inch group at ten yards, that would be a good start point. the old saying is a five shot handheld group if you take the extreme spread of the tightest 3 rounds that is what the gun would be capable of in a MACHINE REST.

[okie john]

10-round groups for sight in? Or can you accurately sight in with less since this isn't as precise a game as rifle shooting? Or does it need more?

I've gone around and around on this while trying to figure out the best sights and zero for my pistols. I believe that while pistols aren't as precise as rifles, we have to use them precisely at the ranges at which they're used, and that means getting--and verifying--a rock-solid zero.

I shot several hundred five-shot groups out of a G17 with an RMR02 while testing loads for accuracy and POI last year. I learned a lot of interesting stuff that pertains to your original question.

1. All of the M4C SMEs recommend zeroing a pistol at 25 yards.
2. You won't see much difference in group size and POI at 10 or even 15 yards, but things start to get interesting at 25.
3. Five-shot groups don't really show what's going on with a given gun, shooter, and load, either in terms of group size or POI. After all, we've all shot five-shot groups that give us bragging rights, then had trouble keeping five in the black with the same gun, load, and target a few days later. Several 10- and 20-shot groups with a given gun, shooter, and load give a much clearer picture of what that combination is likely to do over the long term. They also let you identify and allow for shooter error.
4. POI for windage and elevation can vary surprisingly between loads. I have a G19 that will stack 124-grain +P Ranger ammo in the 10-ring at 25 yards. It shoots a particular brand of 147 FMJ just as well, and to the same elevation, but groups are three inches to the right.
5. Duty ammo and practice ammo from the same maker might chronograph the same and they might hit the same POI. Or they might not.
6. Duty ammo is almost always far more accurate than practice ammo.
7. The bullet weight and velocity of factory loads are useful for predicting the amount of variance with a given semi-auto pistol, but are much less reliable for predicting variance between different semi-auto pistols. This is completely the opposite of how it works with revolvers, which seem to be much more predictable.

As a result of all of this, I now zero by getting the gun to shoot 10-shot groups that are roughly centered at 15 yards. Then I refine that by shooting several 20-shot groups at 25. (I'll shoot 20-shot groups at 50 yards if I feel bold.) When I get two 25-yard, 20-shot targets fired on different days that have an equal number of hits on the left and right of the target's centerline, I feel confident that that my windage zero is dialed in. I do the same for elevation at 25 yards, then call it good.

Whether it's a good idea to economize on zeroing your duty pistol/ammo combination is a separate issue. Determining the offset between your training load and your duty load as A62Rambler pointed out is one way to start, but you really need to be confident that your go-to-war load is dead-on. Shooting a few hundred rounds of it to confirm reliability and zero is a lot cheaper than having problems when lives are at stake.


Okie John