What is the best range to zero my 10.5?

[bagman]

Not a good topic to explain in a post. See F2S response for the short answer. An MPBR zero won't necessarily work for everyone. I use it primarily because I do a lot of reloading with a lot of different bullets and charges and it provides a known constant that will be really close at most reasonable distances with a variety of cartridges.

Google Maximum Point Blank Zero for an understanding of what I am talking about. It is typically used by hunters with a grasp of ballistics and the cartridges they are shooting.

Here is a good start for you.

http://www.rmvh.com/MPBR.htm

Great article. That helped a lot. Thanks

[ABNAK]

Actually, you don't.
The second point of intersection is generally way short of 200 with such short barrels.
Even with M193, your going to be about an inch high at 100, and 5 inches low at 200, which to me, sounds more like a 100 meter zero than the Santoz IBZ.

Because of the low velocities of 10.3-11.5 inch 5.56 guns they tend to defy convention on zeroing concepts. If you want a 200 zero, I recommend shooting at 200, as a 50 is actually closer to a 100.

So what range would you suggest to zero an SBR-length 5.56 weapon at, keeping in mind that I would prefer a minimal trajectory out to say 200 meters? In other words like the IBSZ but tweaked for the shorter barrel.

Then we get into the bullet weight and BC thing I guess. With a carbine barrel the IBSZ is *roughly* doable for M855, Mk262, TAP T-2, 70gr "Brown Tip" Barnes TSX, and Mk318 (all 5.56 NATO pressure rounds, no .223). Sure, it isn't EXACTLY perfect but "close enough for gubment work" from one round to the next. Obviously this will be skewed significantly by the shorter 10.5" barrel and therefore even more variance in velocities.

If you could answer the bolded question it'd be greatly appreciated.

[Terryw123]

What kind of accuracy are you guys getting out of your 10.5?


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[Failure2Stop]

So what range would you suggest to zero an SBR-length 5.56 weapon at, keeping in mind that I would prefer a minimal trajectory out to say 200 meters? In other words like the IBSZ but tweaked for the shorter barrel.

First things first: the IBSZ is NOT a 50 yard/200 meter zero.
What it is, is a method of adjusting A2 rear sights to provide a 200 meter POA/POI intersection, while retaining the accuracy of the other range indications on the A2 rear sight, AND a 50 yard zero (an improvement over the past 36 yard zeroing method).

Since the A2 style rear sights have faded merrily into the past, we can dispense with holding onto the name of the readjustment method of the rear sight (which in the USMC was simply called "setting the rear sight" during my tenure), when the real issue is what the trajectory provides, and can be referred to simply by distance and offset (if applicable).

If you want a 200 yard/meter zero, only actual distance will suffice.
Initial point (the first point the trajectory crosses the line of sight) will be around 35 yards, but I would not put confidence in such a close zero. Alternately, you could do 2.5 inches high at 100 yards.

A 50 yard zero will put you about an inch high at 100, and around 3" low at 200.

A 100 yard zero will still give you many of the advantages of a 100 meter/yard zero as it does with 14.5 and 16 inch barrels, but the lower velocity will put the bullet hanging out at the point of coincidence for a shorter distance. A 100 yard zero will actually have the initial point at around 70-75 yards, but will only rise 0.1 inches above the LOS, pretty much making it irrelevant.

Frankly, a 100 and 50 yard zero look extremely similar, with only an inch of difference in POI at 100 yards. Since minor errors at 50 yards can turn into major issues, and a 100 yard zero is twice as precise as a 50 yard zero (which is a factor as distances and precision performance requirements increase), I would recommend either POA/POI at 100 yards/meters or 1 inch high at 100 yards/meters.

[LastRites]

If you to hit 200 well, sight in for 200 and then find out what is the short distance.

[HKGuns]

If you to hit 200 well, sight in for 200 and then find out what is the short distance.

Huh? I don't know if you got hit by auto-correct but I'm not following that one.

[ABNAK]

First things first: the IBSZ is NOT a 50 yard/200 meter zero.
What it is, is a method of adjusting A2 rear sights to provide a 200 meter POA/POI intersection, while retaining the accuracy of the other range indications on the A2 rear sight, AND a 50 yard zero (an improvement over the past 36 yard zeroing method).

Since the A2 style rear sights have faded merrily into the past, we can dispense with holding onto the name of the readjustment method of the rear sight (which in the USMC was simply called "setting the rear sight" during my tenure), when the real issue is what the trajectory provides, and can be referred to simply by distance and offset (if applicable).

If you want a 200 yard/meter zero, only actual distance will suffice.
Initial point (the first point the trajectory crosses the line of sight) will be around 35 yards, but I would not put confidence in such a close zero. Alternately, you could do 2.5 inches high at 100 yards.

A 50 yard zero will put you about an inch high at 100, and around 3" low at 200.

A 100 yard zero will still give you many of the advantages of a 100 meter/yard zero as it does with 14.5 and 16 inch barrels, but the lower velocity will put the bullet hanging out at the point of coincidence for a shorter distance. A 100 yard zero will actually have the initial point at around 70-75 yards, but will only rise 0.1 inches above the LOS, pretty much making it irrelevant.

Frankly, a 100 and 50 yard zero look extremely similar, with only an inch of difference in POI at 100 yards. Since minor errors at 50 yards can turn into major issues, and a 100 yard zero is twice as precise as a 50 yard zero (which is a factor as distances and precision performance requirements increase), I would recommend either POA/POI at 100 yards/meters or 1 inch high at 100 yards/meters.

Thanks for the reply.

I have a home range but it is only 100yds. I will try the 2.5" high at 100 for an approximate 200yd zero. I would not likely be engaging something past 200yds with an SBR length barrel anyway so knowing that my trajectory doesn't veer from LOS more than a couple inches out to 200 is GTG for my purposes. I could always hold over for something past 200 if I had to.

[Failure2Stop]

Thanks for the reply.

I have a home range but it is only 100yds. I will try the 2.5" high at 100 for an approximate 200yd zero. I would not likely be engaging something past 200yds with an SBR length barrel anyway so knowing that my trajectory doesn't veer from LOS more than a couple inches out to 200 is GTG for my purposes. I could always hold over for something past 200 if I had to.

Just an FYI, I used M193 for this.
I generally go with a 100 meter/yard zero for 5.56 with optic, confirmed with the actual ammunition to be used. I have seen significant differences when changing ammunition, not only when going from type, such as M193 to Mk262, but even when changing manufacturer or lot. Sometimes they are close, but sometimes they are significantly different.

[ABNAK]

Just an FYI, I used M193 for this.
I generally go with a 100 meter/yard zero for 5.56 with optic, confirmed with the actual ammunition to be used. I have seen significant differences when changing ammunition, not only when going from type, such as M193 to Mk262, but even when changing manufacturer or lot. Sometimes they are close, but sometimes they are significantly different.

Slightly off topic but regarding differences in a specific type of ammo: my buddy was pulling some old 30.06 M2 AP Ball bullets from the cases. All but a few were a stick powder weighing 40-some-odd grains. The handfull that were different were a ball powder at 50-some-odd grains. Same spec rounds (all LC), but most were a '54 headstamp while the few ball powder ones were '72 headstamp. This could easily explain velocity differences (and hence slight variances in trajectory) among the same type of round, even from the same manufacturer.

[kpinole]

Slightly off topic but regarding differences in a specific type of ammo: my buddy was pulling some old 30.06 M2 AP Ball bullets from the cases. All but a few were a stick powder weighing 40-some-odd grains. The handfull that were different were a ball powder at 50-some-odd grains. Same spec rounds (all LC), but most were a '54 headstamp while the few ball powder ones were '72 headstamp. This could easily explain velocity differences (and hence slight variances in trajectory) among the same type of round, even from the same manufacturer.

Wow, that explains a lot! That's quite a difference.