M240 shoots what round through what barrel length?

[problemchild]

Tried numerous times now to get this info from Trijicon for the BDC inside the TA11H-308 Acog. They really have no clue and cant direct me to anyone who does. Sent numerous emails all go unanswered. The scope says for M240 inside the glass. But what round from what barrel length? There are several makes of the M240.

Model Cartridge Weight Cartridge Length Propellant Projectile Weight Chamber Pressure Velocity
78 ft (23.8 m) from muzzle
M59 Ball 393 gr (25.47 g) 2.8 in (71.1 mm) WC 846 150.5 gr (9.75 g) 50,000 psi (3,515 kg/cm²) 2,750 fps (838 mps)
M60 HPT 412 gr (26.7 g) 2.8 in (71.1 mm) IMR 4475 171.5 gr (11.11 g) 67,500 psi (4,745 kg/cm²) N/A
M61 AP 393 gr (25.47 g) 2.8 in (71.1 mm) IMR 4475 150.5 gr (9.75 g) 50,000 psi (3,515 kg/cm²) 2,750 fps (838 mps)
M62 Tracer 383 gr (24.81 g) 2.8 in (71.1 mm) WC 846 142 gr (9.2 g) 50,000 psi (3,515 kg/cm²) 2,750 fps (838 mps)
M62 Tracer OFM 387 gr (25.08 g) 2.8 in (71.1 mm) WC 846 146 gr (9.46 g) 50,000 psi (3,515 kg/cm²) 2,750 fps (838 mps)
M63 Dummy 258 gr (16.72 g) 2.8 in (71.1 mm) N/A ? N/A N/A
M64 Grenade 295 gr (19.12 g) 2 in (50.8 mm) WC 830 N/A N/A 160 fps (49 mps) 5.5 ft (1.7 m) from muzzle, projected grenade
M80 Ball 392 gr (25.4 g) 2.8 in (71.1 mm) WC 846 146 gr (9.46 g) 50,000 psi (3,515 kg/cm²) 2,750 fps (838 mps)
M82 Blank 235 gr (15.23 g) 2.6 in (66.04 mm) SR 8231 N/A N/A N/A
M118 Special Ball 390 gr (25.27 g) 2.83 in (71.88 mm) WC 846 or IMR 4895 172 gr (11.15 g) 50,000 psi (3,515 kg/cm²) 2,640 fps (805 mps)
M160 Frangible 315 gr (20.41 g) 2.8 in (71.1 mm) SR 8074 108.5 gr (7.03 g) N/A 1,320 fps (402 mps) 100 yd (91 m) from muzzle
M172 Dummy 385 gr (24.95 g) 2.8 in (71.1 mm) N/A ? N/A N/A
M276 Dim Tracer 381 gr (24.69 g) 2.8 in (71.1 mm) WC 846 140-150 gr (9.07-9.72 g) 50,000 psi (3,515 kg/cm²) 2,750 fps (838 mps) GMCS
2,680 fps (817 mps) GM
M852 Match 385 gr (24.95 g) 2.83 in (71.88 mm) IMR 4895 168 gr (10.89 g) Hollow point 50,000 psi (3,515 kg/cm²) 2,550 fps (777 mps)
M993 AP 362.6 gr (23.5 g) 2.8 in (71.1 mm) Bofors NC1290 126.6 gr (8.2 g) 55,115 psi (3,875 kg/cm²) 2,985 fps (910 mps)

 

[Postal0311]

Re: M240 shoots what round through what barrel length?

IIRC the M240 has about a 24-25 inch barrel.

 

[Trigger Monkey]

Re: M240 shoots what round through what barrel length?

I ran into the same problem last year when I was trying to get the subtension data from them for the TA31F and TA01NSN reticles. While I did manage to talk to them on the phone and they were receptive, the information they sent me however was useless, and after that they put me on ignore. I had to use the ammunition and velocity data they gave me orignially to match up some data I had previously for the RCO-A4.

In your case I'd say use the M80 ball data they have a 146 gr projectile at 2750 fps. Are you trying to match up the reticle to the ammunition you are using?

 

[KClark]

Re: M240 shoots what round through what barrel length?

M80 ball, 23.5"+/-

 

[DP425]

Re: M240 shoots what round through what barrel length?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KClark</div><div class="ubbcode-body">M80 ball, 23.5"+/- </div></div>

+1

MV is listed as about 2970fps

 

[Guest]

Re: M240 shoots what round through what barrel length?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DP425</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KClark</div><div class="ubbcode-body">M80 ball, 23.5"+/- </div></div>

+1

MV is listed as about 2970fps </div></div>

2970, Seems a bit high. I though M-80 was about 2750 as that is what I was using awhile back and it was very close to what I was seeing down range.

 

[DP425]

Re: M240 shoots what round through what barrel length?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Gunfighter14e2</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DP425</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KClark</div><div class="ubbcode-body">M80 ball, 23.5"+/- </div></div>

+1

MV is listed as about 2970fps </div></div>

2970, Seems a bit high. I though M-80 was about 2750 as that is what I was using awhile back and it was very close to what I was seeing down range. </div></div>


well, 2970 is what I recall the FM to say- FNH says 2800 even... so I guess pick which sounds better (I do agree, 2970 sounds a bit high, but i haven't chrono'ed a 240 either)

 

[problemchild]

Re: M240 shoots what round through what barrel length?

So if I am trying as best as I can to match the drop of the 150gr M80 2750fps round shot out of a 23.7" barrel in my 16" LMT could I use a 155 smk palma with better drag resistance to reduce drop and compensate for the slower velocity?

Or is there a better way to do this? I am open to any suggestions. Would like to be close to the BDC from 2-600 yds if possible.

 

[phxfa]

Re: M240 shoots what round through what barrel length?

I just went through this nonsense with Trijicon, same rifle, same optic same bullshit, looking forward to what you come up with. I went out to the desert this past weekend and was just banging away at 10-12 inch rocks at all ranges 100-700 yards and everything in between with Radway ammo (2650 fps) out of my LMT with surprising success. Not an accurate test for the BDC but close especially at 400 yards plus

 

[SSSamurai]

Re: M240 shoots what round through what barrel length?

The 240 has a 24" barrel, and shoots M80 Ball (147 grain) at 2800 fps. At least that's what the TMs say....
Jason

 

[DP425]

Re: M240 shoots what round through what barrel length?

Problemchild...

I think the best avenue of approach on this would be to first find out what sort of muzzle velocity you get with the various different loads. You need some sort of starting point- right now you don't have that. You have nothing but variables on the right side of the equation.

Once you know what sort of velocity your gun will get with 155/168/175, you can plug that, along with the BC for each round into a ballistics program. Assuming Trijicon did in-fact use the ballistics for the M240 with M80 ball at 2800fps, determining the BDC set-up should be very easy. Simply plug it all into the ballistics program. Determine which variable load matches best with your test standard.

I wouldn't expect that you can duplicate drops exactly across the entire spectrum of the BDC- no matter which round you go with, it will have a higher BC than the M80... so at some point the M80 will drop significantly more than whatever you decide to go with. An extra 200-250fps will only carry you so far when you're tossing a relatively short flat base projectile (shitty BC). Weather that's at 500 yards or 900 yards, I don't know.

 

[problemchild]

Re: M240 shoots what round through what barrel length?

I have some load data for the LMT. Two people posted chronograph info in the LMT thread. I plugged some of their info and the m80/m240 info into the calc and you are right it stays with the curve to a point and then they separate.



<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DP425</div><div class="ubbcode-body">Problemchild...

I think the best avenue of approach on this would be to first find out what sort of muzzle velocity you get with the various different loads. You need some sort of starting point- right now you don't have that. You have nothing but variables on the right side of the equation.

Once you know what sort of velocity your gun will get with 155/168/175, you can plug that, along with the BC for each round into a ballistics program. Assuming Trijicon did in-fact use the ballistics for the M240 with M80 ball at 2800fps, determining the BDC set-up should be very easy. Simply plug it all into the ballistics program. Determine which variable load matches best with your test standard.

I wouldn't expect that you can duplicate drops exactly across the entire spectrum of the BDC- no matter which round you go with, it will have a higher BC than the M80... so at some point the M80 will drop significantly more than whatever you decide to go with. An extra 200-250fps will only carry you so far when you're tossing a relatively short flat base projectile (shitty BC). Weather that's at 500 yards or 900 yards, I don't know. </div></div>

 

[Grump]

Re: M240 shoots what round through what barrel length?

Let's not over-analyze this from the wrong side. The reticle cannot be changed. You are unlikely to use the "correct" ammo at the "correct" velocity because the accuracy of that stuff sux big-time compared to your most ordinary-performing handloads..at least I hope!

Print out some pages of 1 inch grid if you want to use the reticle that way (that optic on inches/100 yd, true MOA, or mil???). Or 1.038 or whatever if the clicks are true MOA. Or a 0.2-mil at 100 yard grid (0.72 inch between centers on the lines), or 2 cm grid of you use 100 meters.

Cut and tape three sheets together vertically.

Print out a graphic of your reticle, three or more copies.

Mount the optic on a junk rifle or c-clamp to a hunk of wood. Clamp THAT securely to a concrete shooting bench.

Get the vertical target sheets in front of the optic, look through it, and make notes of subtension of reticle features as they appear to YOU. Make those notes on the reticle graphic printout.

Run an "optical box test" to check your clicks for accuracy to the grid.

THAT's your starting data.

Get a good accurate load. Run JBM or your favorite software on it for your most-expected conditions. Output for MOA or inches or mils or click or whatever matches your optic's adjustments.

Plot those come-ups on a clean copy of your reticle diagram. Take that out and SHOOT to confirm holdovers, ON PAPER, and more than once.

Print another reticle diagram and modify from the holdover point notes if needed. 0-400 is likely to be so close that no fudging is needed. Beyond that, expect some variation. My first venture into this stuff revealed that my M80 Ball reloads tracked to within less than 1 MOA with my 168 gr SMK loads on elevation out to 800 or farther. Less speed plus better BC did it.

Unless you're dead set on simplicity and just MUST have the ammo track to the scope, don't try to make your ammo match its holdovers. Learn how your tack-driving load hits on target, compared to the reticle, and just aim accordingly.

 

[problemchild]

Re: M240 shoots what round through what barrel length?

Thanks for the info posted above I will try that.


Finally got the supposedly correct BDC info from Trijicon.

What I need to know so I can reload a round for my BDC is the following:

What grain bullet? 147 grain per consultant data
What speed (fps)? 2810 ft/sec per consultant data, use a B.C. of .398 for any drop calculations
What barrel length was used? 18.75” per FN weapon literature for M240
What gun was used (which model for which branch service)? FN M240B for Marines
Also if you have a PDF for the horseshoe dot reticle use that would be great. All I got was a manual for the donut reticle. Please provide your mailing address as we are expecting new printed manuals to cover all reticles. ITAR prevents us from making this available for electronic transmission. On an immediate level, the center dot is your 100 meter ZERO and there is no 200 mark.



By the way the 155 SMK Palma will stay within -4" of the BDC to 800 at 2670fps chrono at 10'

 

[QuietShootr]

Re: M240 shoots what round through what barrel length?

Mark me another pissed-off customer for the ACOG .308. For fuck's sake, Nightforce publishes detailed diagrams of every reticle they make, yet Trijicon seems to think that information is Super Secret Squirrel.

Makes me want to spend the money to send the thing to an optical laboratory and have them precisely measure that reticle, then give high-res PDFs of it away for free.

 

[ArmaHeavy]

Re: M240 shoots what round through what barrel length?

I was talking with Trijicon a couple years about making a new reticle. In talking with them about that they told me that all their reticles are based off of what the average grunt could get.

Standard ball most of the time. For the 5.56 it was a 60 something(Brain Fart!) grain standard ball. Can't remember off the top of my head, but it was the most common round, and since they want the big .gov and .mil contracts then for them it makes monetary sense to use the most common round. They aren't going to go for anything odd.

And in regards to the secret squirrel like hold up on info. Customer service reps probably wouldn't be able to help with a highly technical question like that, plus they're busy like 1950's switchboard operators. Your best bet is to try and get in contact with a department with specialized info such as that. If they had an R&D section then I would say call there, or Repairs maybe. I'm pretty sure the entire scope has patents on it front to back so there isn't any reason I could find on why they wouldn't be able to tell you.

I hope all I info I just said helps someone or points them in the right direction at least.

 

[battle-scarred]

Re: M240 shoots what round through what barrel length?

when i humped a 240, m-80 ball was the bullet of choice.....

 

[QuietShootr]

Re: M240 shoots what round through what barrel length?

I can run a range card in BulletFlight or Atrag for M80 ball...but I want the EXACT figures they made that reticle with. Plus I want to know what the horizontal hold bars are - they don't do a lot of good if I don't know how many minutes each bar is out from center.

 

[Afghanvet09]

Re: M240 shoots what round through what barrel length?

If your military with these questions asked to be referred to the military/le rep. They will get you the correct info. Customer service reps either don't know or told not to release this info. Went through same thing trying to figure what the difference was between the TA31RCO and TA31F until got referred.

 

[The Savage Rabbit]

Trijicon just told me the TA11H-308G is based on M80 from an M240 with a 20" barrel.

 

[Trigger Monkey]

Trijicon provides the subtension data for most of their reticles now on their website. It only took them the better part of 10 years but hey better late than never.

 

[Plinker 73]

What about the newer high velocity M 80 A1 ball and M 62 A1 tracer both using a 130 grain bullet and faster velocity. It my understanding that is the issue ammo for GPMG now.