I purchased a Vortex Razor HD Gen II-E1-6x24 with a badger C1 1.70 mount. It's my first lpvo and was told the reticle is good for beginnersm My goal was to put it on a 11.5 centurion barrel, however I just learned that the reticle is calibrated for longer barrels. Is that entirely true? I know alot of it is based on ammo. The purpose of the rifle is for it to be a general purpose build. Not looking at making any long range shots. 300m maybe 500.

Best

Damn

Compromise

BDC is an abomination.  None of them are ever exact for any gun, period.  

You just have to find out the values that the stadia actually represent.  To do so you will need to know the velocity of whatever ammo you like, that your gun is producing.

The easiest way I know of to reduce BDC error in general is to zero the 300 yard stadia @ 300 yards.  That will minimize the error overall out to 400 yards.

There is no free lunch, as they say

It's calibrated for 55-77gr going 2700-3000 fps with the center reticle zeroed at 200 yds.

Some people zero the 400 yd line (the 2nd hash) at 400y and the remaining hashes will be close enough to make hits on 10" MGM flashers out to 600y.

With 5.56 55 grain you will be good out to 400. After that, aim high.

I have no idea with 62 grain. The heavies won't line up at all.

Why won't they

Velocity is off too much

The stadia will line up just not at the 3 4 5 and 600 yard lines.

For example an 11.5 zeroed at 50 yards, 75 grain crosses its line at 150 yards and not 200 like the 14.5 and longer.

Plug your velocity and BC along with altitude and weather info in a ballistic calculator and line up your stadia with the closest yardage for the built in drops of the razor. You can google the reticle and it’ll have the drops for each of the stadia in it.

I just went through this with the same scope on my 13.7. I verified on the range.

Really the MRAD model would be better suited for you on the 11.5.

Get the Strelok Pro app and you can see what it all works out to on the actual reticle with your specs.

That is the purpose of DOPE and making DOPE cards for the rifle, optic, and ammo combinations.  Like you said they are not exact and even if you set it up on a rifle with the right barrel length and correct ammo it still will not be exact.  It will be close enough to hit a man size target but you will not be hitting bullseye at all different ranges.
Once you accept BDC’s are never exact and actually DOPE it they instantly become useful.  I learned this long ago buying BDC reticles and guys smarter than me explaining how you can make them useful it all made sense.

Duly noted

Could you expand on this process just a bit, please? Is this a, hold slightly high/low proposistion, or a elevation/wind turret solution.

One nice thing about the JM-1 BDC is that the drop hashes subtend to 9" wide at their respective distances, 200-600Y.

Since most MGM flash targets are 10" wide so you can use the reticle for ranging.

What he is saying is that you find out the actual distance that the stadia of the reticle represent.  With your gun and ammo, the 200 yard line may be 180, the 300 may be 270, etc, etc.  If you can't remember the numbers, make a dope card and carry it with you or taped to the weapon.  Regardless of what the numbers represent, you are going to have to range targets to know which line to use and sometimes you will have to hold-over for 'tweeners.  I do like to dial, but not all scopes are capable.

Got ya and thanks.

A BDC reticle is going to be a little off no matter what you do. Unless you're using the exact barrel length, exact ammo, at the exact altitude and temperature it was designed for. Too many variables. You just have to check it at range with the ammo you are going to use and see if that 400 yard hashmark is actually 410 yards, 390 yards, etc etc. You can use Strelok and see where it will be if you know your muzzle velocity.

FWIW, I used the JM-1 in a Razor 1-6 on a 10.3" SBR for 2 gun for a while. I could hit C-zone steel out to 400m (longest range I ever had to shoot in a match) without issue using the reticle as designed. I was shooting Magtech match ammo (77gr SMK).

I love BDC reticles, especially that one.

I just pick whatever load I want, zero mine, then fine tune it at each distance.  either the 300 or 400 will be dead on, then I will know my holdovers for further distances.  If set dead on for the 400 hash mark, 300 was easily close enough to always hit the steel, and 500 was often just a hash-mark high hold.

I dont get the hate for BDCs. You can easily calculate the drops in strelok, and print a dope card, laminate it, and slap it on your stock or scope body.

Even if a BDC is designed for a specific barrel length, round, etc, you can calculate the drops for a completely different setup and if you know them, you're good to go.

This...  Depending on what you have access to at your range it is kind of a process but once complete the dope card mentioned above becomes your golden ticket.  

So we all know BDC's are great when they perfectly line up with your rifle, ammunition, and conditions but almost none of them every line up perfectly even when it is for the specified rifle and ammo.  They are often close enough to make hits on a man size target but if you want to be able to ethically hunt at distances beyond 100m you really should dope the BDC.  

First off you choose your zero for the optic 100, 50, 36, or even 200 whatever it matters but not as much as you would think.  Once zeroed move to the first drop point in the scope and shoot it at the range it is prescribed for say the 200m.  It may be spot on or you may be X high or low over the bullseye make note of that.  Move to the 300 and repeat till you run out of range to shoot or reach the max distance you plan to shoot or need data on.  It may be hard to get all the exact data at most ranges because they break up the distances usually at 50, 100, 200, and so on.  When you do get the opportunity to shoot at an out of the norm range say like 150 or 220 note how you impact with a hold on the BDC.  Over time as you note more and more data you will develop a very valuable DOPE on the rifle/optic/ammunition because it is tested and verified data that you can repeat.  You can also have multiple ammunition data points where one set of data is M193 55gr, M855 62gr, 69 or 77gr FGMM or match ammo, and so on.  You can note really anything depending how detailed you want to get like temperature or atmospheric pressure as they have effects but that depends on you as the shooter if that data will be valuable to you which usually it is more for the long range precision shooter that this data is useful at extended ranges.

True it up on the longest targets you have, and it will work very well. Alternatively, use a ballistic calc to see how high/low to zero it at 100yds for the 500yd hash to line up. Make sure you input the HOB correctly. With SBRs, taller mounts like 1.93” or 2.05” make the BDCs work more closely, but the 1.7” will keep you on E-types to 600yds. Good enough for 500yd F-types usually, too.

Most people that hate BDCs are zeroing them close, not far. The further you zero them, the closer they will usually be at all distances. This is definitely true of the JM1.