MK 262 Mod 1 Question

[choskins42]

I was hoping someone could help me out. I have a SPR (MK 12 Mod 0 clone) with an 18" 1:8 Douglas barrel that I am setting up to use as my patrol rifle for precision shooting that has to be done before our sniper team can get set up. I'm using Black Hills MK 262 Mod 1 ammo. I'm having a Leupold scope customized to match the 77gr instead of the factory 62gr. I need to know some info to give Leupold and unfortunately I'm out of the country and having problems finding the correct specs online. I believe the answers for Caliber is 223/5.56 and bullet weight is 77gr correct? I appreciate any help.

I need to know

Ballistic Coefficient
Muzzle Velocity
Caliber
Bullet Weight

[Belmont31R]

Muzzle velocity cannot be 100% known without running your gun/ammo through a chrono.



http://www.sierrabullets.com/index.cfm?section=bullets&page=bc&stock_num=1478&bullettype=0

[Rmplstlskn]

Yep... You could use results from a "standard" 18" barrel which will be close, but it still would be guessing on your barrel...

Rmpl

[choskins42]

I was just hoping with this rifle type becoming more popular that someone would have the same set up as me.

[Belmont31R]

My method to calculate velocity is not as accurate as a chrono but I use the KAC bullet flight software on my phone, and reverse calculate it based on the drop I get at various ranges. With my 18" Centurion Mk12 barrel I reversed my real world dope into the software and get 2825 FPS with Mk262Mod1 white box seconds.


What you do with the info is up to you.

[choskins42]

Belmont31R:

Thanks for the chart. I have two questions though, on the chart it says .224 do I put that as the caliber or do I still put .223/5.56? And I don't know how reliable this is but on the wikipedia page for the MK12 SPR it has the muzzle velocity at 3050 how reliable do you think that is?

These are probably dumb questions but I've always been an operator and never took the time to learn about bullets other than grain weight, so thank you for taking the time to answer my questions.

[Belmont31R]

Belmont31R:

Thanks for the chart. I have two questions though, on the chart it says .224 do I put that as the caliber or do I still put .223/5.56? And I don't know how reliable this is but on the wikipedia page for the MK12 SPR it has the muzzle velocity at 3050 how reliable do you think that is?

These are probably dumb questions but I've always been an operator and never took the time to learn about bullets other than grain weight, so thank you for taking the time to answer my questions.



224 is the caliber of the bullet. 223/556 is the size of your barrel. Thats why when you look at a fired bullet you can see the impressions of the grooves/lands on the bullet. Its for a proper seal between bullet and bore.


3050 seems fast to me. Do a search for molon posts. He has the best load data of anyone on the net.

[Rmplstlskn]

This may help you some...

http://www.wwyd.org/images/AR15/Ballistics_MK262.gif

Love that MK262 Mod1... It is my chosen self-defense round. Very accurate!

http://www.wwyd.org/images/AR15/BH_MK262-Mod1.jpg

Too bad it is almost impossible to find outside the military now days...

Rmpl

[Belmont31R]

BH has released a commercial version of it. 5.56 pressure with 77SMK.

[choskins42]

Belmont31R:

OK so for scope purposes when it asks for caliber I would put .224 correct? The ammo I use is the actual MK 262 Mod 1 white box.

My problem is I'm actually military (national guard) so I've took advantage of having all my equipment and ammo just handed to me so I never took the time to learn about it and now that I'm having a rifle and scope custom built I feel like an idiot because I've been using this platform for more than a couple years but can't describe the specs that I need.

Rmplstlskn:

Wouldn't your chart be off from my barrel since the chart you have is for a 16" barrel and mine is 18"?

[Belmont31R]

I think Leupold has a custom shop turret for the Mk262Mod1 since it was a contract scope for the Mk12. Maybe try giving them a call tomorrow and asking.



https://www.m4carbine.net/showthread.php?t=26127&page=3



Molon lists the Mk262 getting 2830 out of his 20" Colt CL'ed barrel.

[Rmplstlskn]

Rmplstlskn:

Wouldn't your chart be off from my barrel since the chart you have is for a 16" barrel and mine is 18"?

The chart has both 20" and 16" and the difference looks to be 120fps. Maybe half that for an 18"? That is 2790fps...

Without doing your own chrono work, I don't think you can get much closer than that, nor do I think a few fps here or there will matter all that much... But I'm just a novice, don't take my opinion as gospel...

Rmpl

[choskins42]

Belmont31R:

I know this is probably starting to sound like I just keep on asking questions just to ask but I'm not I swear. I actually did call there office today and the person I spoke with told me that they did not keep that data on file I'd have to find out for myself which surprised me since they have been making all sorts of optics for that rifle for years.

I'm going with this optic
Leupold Mark 4 1.5-5x20mm MR/T (30mm) M2 Matte Illuminated SPR. And because this isn't going to be a target rifle and the nature of the business I really want the hold overs to work for fast references. I know it would be a lot easier to us one of their other optics that isn't already set up for the 62 gr like the Mark 4 3.5 10x40, or 2.5 8x36 but I need something I can go CQB with quickly. The county I'm a deputy in has farm lands but also quite a bit of urban area as well so the ranges we operate in vary quite a bit.

[Belmont31R]

Im not sure what to tell you without you doing your own ballistics testing, relying on others data or trying to find an M2 Mk262 turret.



Here is one of Molon's velocity charts: http://home.comcast.net/~gocartmozart/MK262_vs_556_TAP_muzzle_velocities.jpg



Without your own data I think you are going to have to come up with a velocity number mixed with the actual bullet information I linked to.


I can tell you I shoot with a Schmidt and Bender Short-Dot 1.1-4X which has a turret for Hornady 75 grain ammo. I don't pay attention to the ballistics information on the turret. I came up with my own dope charts based on my real world results. If you need to tape a chart to your stock after you develop your own data with the scope, rifle, and ammo. Theres lots of ways guys come up with easy references for their dope. I actually generally prefer scopes that don't have a BDC turret.

[choskins42]

I appreciate all your help. The reason I was trying to do it without having to fire my rifle (but looks like my only option) is I got deployed last minute notice a few weeks ago and am out of the country and can't get to my rifle. I'm not sure how long Leupold's custom shop takes to complete orders and am being impatient and wanted to have the optic waiting for me when I get home.

[Belmont31R]

I think you would be better off just buying the plain M2 turret, doing your own load work, and having them make you a turret. I think it would give you more confidence than relying on other people's load work. I don't like BDC turrets but if thats what you want doing your load work then getting the turret made is the best way to go in my opinion.


How good are you at range estimation? A BDC turret is a small priority in shooting accurately at range which is what seems you are stressing for your LEO job.


I've found the hardest part of shooting LR is judging the environmental effects/conditions. Its easy to come up with range data but MUCH harder to make sure your shot goes where its supposed to go when dealing with wind, changes in temp, ect.

[choskins42]

I'm the same way I actually try to mess with the Turrets as least as possible. What I want acturate is the hold over hash's on the rectile. I got the chance to attend the basic designated marksman class and so I'm pretty good at guesstimating ranges and using the Mil dots to hit the target. Well the optic I'm looking at doesn't have a mil dot reticle it has its own that is set up for 62gr, so if I'm firing 77gr the hold overs are going to be incorrect.

[Belmont31R]

I also happen to not like BDC reticles. I like generic turrets and reticles so they are not caliber/round dependent, and turrets that match the reticle.



Have you thought about just getting the MRT with a plain mil dot reticle?

[ALCOAR]

Are you sure you contacted luepy about this.....:confused:

http://i374.photobucket.com/albums/oo183/WldWldWest/DSC00204.jpg

[Belmont31R]

Yes I was going to say Ive seen people get those turrets as recently as a few months ago.

[choskins42]

Yes I'm positive I called this afternoon as soon as I got in my office. I asked if they already had the data saved for this ammo type and he said no it was something I needed to supply them. Now maybe I was just speaking with the new guy or maybe they have the turrets saved but not the reticle info. But he told me to contact the guy in charge of LEO/Mil sales tomorrow (Tuesday) and speak to him about pricing so maybe I'll ask him and see if he's any more familiar with the data and has a better answer for me. I figure even though he's in sales maybe he's been around long enough that he knows the data to.

I'm not sure if they offer their SPR optic with a mil dot reticle, I'm looking right now because that's not a route I'm against especially since I'm already familiar with the system.

[Belmont31R]

http://swfa.com/Leupold-25-8x36-Mark-4-MRT-30mm-Riflescope-P45046.aspx

[shootist~]

I was hoping someone could help me out. I have a SPR (MK 12 Mod 0 clone) with an 18" 1:8 Douglas barrel that I am setting up to use as my patrol rifle for precision shooting that has to be done before our sniper team can get set up. I'm using Black Hills MK 262 Mod 1 ammo. I'm having a Leupold scope customized to match the 77gr instead of the factory 62gr. I need to know some info to give Leupold and unfortunately I'm out of the country and having problems finding the correct specs online. I believe the answers for Caliber is 223/5.56 and bullet weight is 77gr correct? I appreciate any help.

I need to know

Ballistic Coefficient
Muzzle Velocity
Caliber
Bullet Weight

I shoot a lot of 77 SMK (reloads) and small amounts of the Mk 262 Mod 1 5.56 pressure BH commercial load that was just released. I run JBM Ballistics online software which is more or less the bible of ballistic software.

The Ballistic Coefficient (G1) is .362 for velocities between 2,500 and 3,000 fps. This is for the .224 caliber Sierra 77 gr SMK with cannelure.

The velocity for my full pressure .223 reloads in a Noveske 18" SPR barrel is 2,710 (depending on temperature). I have not chronographed my BH Mk 262, but it will be in the range of ~2,800 fps or more in the 18" Noveske. It shoots a good 1 MOA flatter than my reloads.

The 18" stainless Noveske barrel is a fast barrel and will push my 77 SMK reloads just over 100 fps faster than in my 16" Noveske CL barrel. I don't know how the Douglas barrel will compare.

The barrel length won't matter in setting up a BDC turret or reticle. The velocity and BC are all that's needed (plus possibly the expected air pressure or altitude, which become important for long range.)

If you cannot wait for actual chronograph results, I would use 2,800 fps or maybe 2,750 if you shoot at low altitude.

JBM Ballistics' website if you want to play with the numbers:
http://www.jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi

[choskins42]

Belmont31R:

I've looked at that optic already and as much as I've toyed with the idea because I like the distance the optic would provide it would make a huge CQB rifle (inside 10 yards). It would be hard to pick up on a close fast moving target or room clearing. That's why I decided to go with the Leupold Mark 4 1.5-5x20mm MR/T (30mm) M2 Matte Illuminated SPR Rifle Scope ( http://www.leupold.com/tactical/products/scopes/mark-4-mrt-riflescopes/mark-4-1-5-5x20mm-mrt-m2-illum-reticle ). I'm looking right now but I can't seem to find a mil dot in this model, only with the pre-designated hold overs for the 62 gr unless you have them do a custom reticle for you and that's why I needed the muzzle velocity.

[Belmont31R]

Yeah you are right. Getting too late...:o




Have you considered other choices with a generic reticle and turrets? Are you stuck on the BDC turret/reticle?

[choskins42]

No I'm not stuck on any idea, I've looked at several different optics over the last two months or so and for my over all needs this seems like one of my better choices.

I'm trying to stay under $1200 give or take, I need something I can use for(I have an 11.5 SBR that I usually use for urban area but I don't want a rifle I can't use indoors in case I already have the longer barrel out and the subject runs in to a building I don't want to have to use my time out card to tell him to hold fast while I go swap out rifles at my car) CQB, building clearing, or close range suicide/hostage situation, but also want to be able to reach out and touch someone if they happen to be at the other end of a crop field with a hunting rifle or the very end of a high school hallway (one of ours has hallways about 300 yards). I'm not really worried about engagments over 500 yards with this rifle because we have a SRT team with snipers that can be dispatched and if they're further away than that chances are I can hold off for them.

I've looked in to the same type of optic that Burris offers as well as Nightforce and the Leupold seemed like a great middle ground and I have used them (Mark 4 3.5 10x40) on my mil rifle with great sucess but I'm up to other ideas if you have them.

But if anything I can probably get a buddy of mine to take my rifle to the local range and have the muzzle velocity measured, it seems like that is the easiest answer.

[Belmont31R]

Heres my quick take on BDC turrets/reticles. They work great where everything is the same. The military for example. Almost everyone is shooting the same guns and ammo. So they can create a BCD optic like the ACOG which will work the same for everyone. Everyone is using the same gun and ammo. Marksmanship training in the mil is poor at best aside from the specialty guys like snipers/dmr's. Those guys are given the skillsets needed to range targets and make adjustments. They come up with range cards and dopes for their guns. The BDC is a crutch for the less skilled guys. Its easy and it works for them.


Where it becomes an issue, like in our case, is using your gun for duty purposes. Its not the same as the average 11B with an M4, M855, and an ACOG. What if you switch rounds a year from now? Your BDC reticle/turrets are worthless. BDC thingies do not take into account elevation changes, temperature changes, ect.


It takes a little more effort but using a generic reticle/turrets is the better way to go. Your dope will change with the temperature changes season to season, you aren't tied to one round on one gun, you can swap the optic to another gun and still have a useful optic, and not a major concern but no one is going to want to buy a scope with a custom BDC turret on it from your gun if in the future you decide to go with something else.


What I do with my optics and guns is keep a little log on my dope, commit the rounds I shot most into memory, and I utilize the KAC bullit flight app on my phone to help in establishing my data. I don't keep a card on my gun but its pretty popular. Tape it to the stock, dummy cord a laminated copy to the gun...theres lot of options.



Check this scope out: http://nightforceoptics.com/nightforcescopes/SCOPES_OVERVIEW/COMPACT_NXS_MODELS_/compact1-4x24nxs/compact_1-4x24_nxs.html


It comes in 3 reticle choices and 2 turret choices. Its far better to match the reticle increments to the turret increments meaning if your reticle is calibrated in mils you want mil calibrated turrets. It has the option of a mil dot reticle and mil turrets. Other options, too, just throwing this out there as food for thought. NF makes some good optics. Im partial to my SB's but in your budget NF is right up there at the top.

[choskins42]

Well as long as I supply my own ammo (at my office we do for our patrol rifles and SRT ammo is issued) I'll be using the 77gr. I've used both 77 and 62gr in the field and this is just in my very own expierence I'm not trying to put down any other round or debate which is the best but I had much better result with the 77gr.

I had looked at the Nightforce NXS before and only saw the SPR reticle they have but after looking on their website I noticed they have a mil dot reticle system so that might be the direction I go now.

And take it easy on the basic marksman training the military offers its where I learned to shoot, and yes I got much better training in my DMR course but its a great starting point for the average guy off the streets.

[agr1279]

Love that MK262 Mod1... It is my chosen self-defense round. Very accurate!

http://www.wwyd.org/images/AR15/BH_MK262-Mod1.jpg

Too bad it is almost impossible to find outside the military now days...

Rmpl

That lot is really great. The only lot that I have shot that was 08.

Dan