The topic of sizing has made me concered about the dimensions that I've stated on my MA37 and M45 blueprints. While I did research on appropriate sizing at the time of drawing them- Required barrel OD for the 8 gauge and 7.62 calibers, required ejection ports sizes for those shells and grip sizes of current assault rifles- AK, M4, Styer -I feel inclinded to do more research to provide the best and most accurate blueprints I can. Here we go-
I started the AR blueprints with the barrel, and an 18mm OD was reasonable for the 9.5mm round...
Umm, WRONG! The MA series uses 7.62 x 51mm FMJ rounds, which is what I drew the blueprint up to suit.
I quickly replied to that post and grabbed that caliber from my copy of Halo Encyclopedia, which listed the MA5 series as using 9.5mm x 40 FMJ rounds. Yet later in the book (mere pages in fact) it shows a 7.62 x 51mm FMJ round and states them been used in the MA5B. And every other reference source states that the MA5 series uses 7.62mm rounds. The Halo CE instruction manual on the MA5B, Halopedia on the- MA5B, MA5C and MA37, Bungie.net on the MA37. But none the less further research indicates that 18mm is a perfectly reasonable OD for a 7.62 caliber weapon.
But, I'm still not 100% covinced my stated length of 880mm is the best size to build props to. So, more research.
The MA37 is an earlier version of the MA5B (Halo CE) and MA5C (Halo 3). While they are different guns they are of the same series and therefore would be using some of the same parts. I've been told that Adam's AR is 800mm without the barrel, so I took a copy of Wizard of flight's MA5C blueprint put it into autoCAD and scaled that area of the rifle to 800mm. I was happy to discover that the barrel OD came in at 17.7mm almost spot on to my blueprint's 18mm. I then overlapped Wizards blueprint with mine to see what other similarites there were.
And the answer was- hardly any. While at a glance to us the MA37 and MA5C look very similar, upon closer inspection their layouts and angles are noticably different, which leads me to believe the only real common parts they share are internally. But surely they'd have some common parts? The Barrel is all I can come up with.
The top image is Wizard's blueprint at 800mm without barrel.
Middle is mine scaled with 18mm OD on the barrel as in my current blueprint.
Bottom is scaled to the bungie.net wire frame prop length of 800mm overall.
The bottom ones barrel OD comes in at 16.4mm, noticably different to 18 and 17.7mm, meaning that if the MA37's were in fact this size they would share no external parts at all (that I can see) with there later model brothers. Not that this is not possible, 16.4mm is still totally acceptable for a 7.62 caliber weapon and many weapons currently in service have evolved into nearly completely different beasts to what they started as.
One thing I was concerned about though is the size of the ejection port and if it could cope with the 51mm shell at this overall size.
62mm seems like acceptable clearence to me.
At this point in time I was still clinging to my original length of 880mm as I wanted there to be some external connection to the later models of the MA5 series. So I turned to reference pictures.
Which let me down. Using some 1:1 scale toy guns I have here- An M4 at 800mm and an EBR variant with collapsed stock at 890mm -I did some size comparisons by eye with Reach in game reference pictures. Even on Kat, who would be closer than most Spartans to the average sized male, the MA37 looks to be more like the 800mm long than my blueprint's 880mm.
I'd like to do a cutout at 800mm to totally confirm it, but at this point I would be inclinded to say that the MA37 and it's younger brothers- the MA5B and MA5C -share no external parts and if you were to use my blueprint as a guide for a build you'd be better off going with an overall length of 800mm.
I'll report more when I've done a cutout.