Gr corolla forum

This is an analysis of the Old vs New MR762, compared to the new SDMR, in terms of accuracy, precision and ballistics. This will be a dynamic post, and I will update it as new information becomes available to me.
INTRODUCTION TO THE M110A1
I was privy enough to see the disassembled differences between the MR and the SDMR. I've been trying to understand why HK went to a Medium Contoured barrel when the harmonics offered so much on the heavy 1:11 twist barrel.
Well, turns out the Army themselves went with a medium contoured barrel. So why the change? They're making the MR barrels on the same assembly line as the SDMR barrels, just with a different twist rate.
Both barrels are RH Twist 4 Land Groove, and both use the same materials for barrel construction, HK's French Cannon Grade Steel. I cannot confirm personally if the SDMR is chrome lined. And some details still are considered sensitive and confidential. The new M110A1 SDMR is a 16.3" Medium Contour Barrel in 1:8 twist that fires M118LR exclusively for a full 2-rotation of the projectile, with a base velocity of 2379ft/s. It uses its own proprietary gas block and barrel nut, compared to the commercial MR762.
M110A1 Barrel Nut
The barrel nut has me interested, along with the different gas block. I would like to see the inside of it and its design compared to the MR gas block, and understand what changes were made for the SDMR.
M110A1 Gas Block
There are currently too many unknowns when it comes to the gas block. It is beefier than the MR, and only has one single roll pin. Gassing will expectedly be different. As for the extension up top, this is unknown at this time.
MR762 Old vs New Barrel Profile
The old heavy barrel was 2lbs 6.2oz. The new contoured barrel is now 1lbs 14.5oz, as shared by CTYatty who took some awesome photos of barrel profile details. (ctyatty). This makes a difference on the warfighter who has to carry it, and for faster dissipation of heat soak.
MR762 Old vs New Barrel Weight
As for the change in twist rate from 1:11 to 1:12, verus the SDMR using 1:8. That is more involved, and I will reference images I got from said forum member, and my own research, which is modified and originally taken from my initial question to this on Reddit: Short Barrel (16.5") Long Range: 1:11 vs 1:12 to reach a kilometer? : longrange (reddit.com)
BARREL CONTOURS & TWIST RATES
Heckler & Koch moved from a fantastic 1:11 Heavy Barrel in their MR762 line of DMR rifles, to a 1:12 Medium Contour, as the photo shows. The Berger Stability Calculator shows the 1:11 is more effective offering a more stable round versus 1:12.
My question is, what are the advantages of using a slower 1:12 twist rate with a lighter barrel versus the faster, heavier 1:11 twist rate? And by extension, what's the best route to go to maximize the effective range of a .308 Win round in the MR's barrel profile?
As far as I've learned, the Slower 1:12 twist rate is a negative, not a positive. The M110A1 DMR, G28 DMR and MR762 with heavy barrel are designed to have an effective range of 600-800 meters, and can reach more than 1000 meters at the right altitude. Can this same barrel in 1:12 and lighter weight reach out just as well, but using a different bullet?
The M40 had a 1:12 twist rate and was designed to use 168gr right? So then the same way of asking this question is, why did they chose 1:12 and not 1:11 for the M40, and subsequently, why 168gr and not 175+gr at the time for use with 1:12, other than using a 24" barrel for two complete rotations?
I've begun answering my question, learning that the FN SCAR 17S is also a 16" barrel in 1:12 twist, and using the data from Hornady's website: http://www.shooterscalculator.com/ballistic-trajectory-chart.php?t=13aee2da REF: 168 gr ELD® MATCH TAP® AR™ - Hornady Law Enforcement
The TL;DR answer: the difference is negligible.

• Muzzle Velocity - 1:11 2507 fps vs 1:12 2500 fps
• 500 Yard Velocity - 1:11 1914 fps vs 1:12 1908 fps
• 1000 Yard Velocity - 1:11 1425 fps vs 1:12 1421 fps
• 1100 Yards (1000M) - 1:11 1344 fps vs 1:12 1340 fps

Altitude: 6476ft TEMP: 75F BAR: 30.16Hg HUM: 16% Hell, even at 1400 yards before the round hits transonic, its 1147 fps vs 1144 fps. So back to the original question:

1. Does changing from 1:11 to 1:12 make a difference on the 16.5" barrel? No, not with the Hornady TAP ELD AR round at my altitude of 5200-6200 feet.
2. Was there a valid reason to switch froma Heavy Barrel to a Mid Contour barrel? Yes, it shaved 1.1lbs from its weight.
3. Was there a valid reason to switch from 1:11 to 1:12 twist rate? It's not worse, but it's not better using 168gr or even 175gr .308. One answer is, modern match-grade rounds were being over-spun and not reaching their best potential from a 16.5" barrel. This thinking could be in line with historical US weapon systems like the M40A3 which features a 24" 1:12 barrel versus the original M40 with a 1:10 twist.
4. Working theory: HK's new Mid-Contour 1:12 Barrel changed the bullet stability for modern FMJ and Match Grade rounds, attempting to prevent over-spin and possible bullet destruction from the hot rounds on the market today >> It hasn't fully answered my question, but I'm now able to quantify more and more data because of it: Bullet Gyroscopic Stability Calculator (bisonballistics.com)

H&K 2022 MFD MR762 LRPIII with newer gas block, clearly and effectively cycling Hornady TAP ELD AR 168gr, and producing Sub-MOA 3-round shot groups.
https://preview.redd.it/cgf06dmq6h4b1.jpg?width=1440&format=pjpg&auto=webp&s=e3ff0a0806f9e5f63e7c22e7c5102e1a1fafd9c5
The German Military selected the 1:11 heavy barrel for the G28 DMR to push standard 7.62 NATO 150gr FMJ (M80) rounds to 1.5MOA. That was the standard required by the Bundeswehr. After years of use and changes to bullet manufacturing and ballistics over the last 20 years, HK may have found better ballistics from a 1:12.
So why 1:8 for the M110A1? They want two complete rotations of the projectile from the 16" barrel, just like the M40 had 1:12 for a 24" barrel. They want to maximize bullet stability from the M118LR 175gr at any altitude and in harsh or cold conditions where air density is at its worst to give the best precision possible. And since the M110A1 SDMR will only be using M118LR or lighter as used in military service, they basically aimed to push M118LR to its limits of spin rate before fragmentation i.e. "over-spin."
This is over-spin: Reddit - Overspin Video
ANALYSIS OF THE NEW MR762
What does this mean for the new 2021+ MFD MR762 with Medium Contour 1:12 barrel?

1. It has a new gas block, allowing for more gas to cycle through the system, and in effect, maximize all modern .308 rounds on the market.The new MR is designed to run even the lightest .308 rounds for maximum effectiveness, and not having failures to feed as seen in the first generation of MR762s which were sensitive to what ammo they used.
2. By switching to the 1:12 twist rate, the new MR can better utilize lighter ammo at and under 168gr, and better utilize M80 ball ammo. In so doing, because it is pushing a lighter round, it needs to push hotter for spin rate balance. So using hot consumer ammo such as Hornady A-MAX or Hornady Black, will have better ballistics.
3. By being lighter, and treated as a Match-Grade rifle, a lighter barrel will cool down faster between rounds. If treated as a combat rifle, the MR will overheat faster than its previous version. The MR, by name, is designated a "Match Rifle" and if treated as such, will gain advantages in its new profile. But despite this, its metallurgy can take quite a beating. Just expect some heat shift if used heavily.

CONTOURED BARREL THERMAL CHARACTERISTICS by @JRB
A lighter barrel has a lower total heat capacity because:

1. It has less mass
2. It has less surface area

The lighter barrel will cool faster because it has a lower heat capacity, due to having less surface area than a heavier barrel to retain heat. Meaning that if you had a light barrel and a heavy barrel that were otherwise the same length and material, and you raised the temp of both to 250 degrees, the lighter barrel will probably cool to 100 degrees faster than the heavy barrel in most normal environments.
In real world use, this means the light barrel will also get to a higher temp with fewer rounds fired, because less heat capacity equals less heat energy required to elevate the temp.
But for a DMR -- with a very slow expected firing rate and emergency firing rate -- the lighter barrel will likely not heat up enough during normal Designated Marksman use to cause this from happening.
So if the necessary accuracy standard can be achieved with a lighter profile barrel that can also sustain the expected emergency firing rate with issued ammo, the reduced weight from the heavy barrel profile is well worth the trade-off in total precision max possible fire rate.
REAL WORLD BALLISTICS
I will modify and tweak this as time allows. But for reference, here are ballistics from various rounds from a 2012 MFD MR762 Heavy Barrel with 1:11 Twist:

• Federal Golden Match 175gr - Single Failure to catch and chamber a new round, Solid Groups
• Winchester M118LR 175gr - Malfunction, Jam. Failure to chamber a new round.
• Hornady TAP ELD AR 168gr - Does not chamber a new round, Solid Groups with 1MOA capability.
• Norma Golden Target 175gr - Solid Groupings, no failures, 1.5MOA demonstrated capability.
• Hornady TAP ELD Precision 168gr - Runs hotter than the AR ammo, unreliable groupings.
• Federal Berger Juggernaut 185gr - Runs hot, requires greater rifle control to maintain precision.

10-round shot groups from a 2012 MFD MR762 DMR, which is not as forgiving to various ammo types compared to the newer MR762 LRPIII despite the same 1:11 twist. ​
https://preview.redd.it/bu0vkhdx6h4b1.jpg?width=1280&format=pjpg&auto=webp&s=a65674d03cb8e07ed3c80dc17ff212790b3ba053
CONCLUSIONS
So with all this information, we can conclude that the new M110A1 SDMR was designed to push M118LR 175gr under any condition, at any altitude, at the sacrifice of some MOA and ammo sensitivity like we see in the first generation MR762 (2MOA was the contract requirement).
The new MR762 from 2021 onward is designed to be much more flexible in the ammo it runs, and designed to not require expensive match-grade ammo to get solid performance from it. I wish to try Hornady Black 168gr from the new MR to see its performance.
I invite anyone with an MR to show their 10-round groupings on paper at 100 yards to demonstrate what their rifle can do, whether it be the 1:11 twist, the new 1:12 twist, or any service members with an SDMR willing to show their 100 yard groupings.
Please ensure you share: 1. Which profile barrel you have (or twist rate) 2. What ammo you used for your MR or SDMR 3. What temperature & altitude you were shooting at

Copypasta'd off Sneakers but I also wanted to share these here!
Got these off the SNS raffle and they arrived a couple of days ago.
The polyurethane coat is not heavy so the leather really shines. The white leather panels feel nice and soft to the touch - Definitely better than GR Adidas sneakers. Fairly thick leather panels relative to most sneakers. The suede toe panel feels pretty nice as well. The laces feel very thick and durable - definitely an underrated thing to consider in shoes. They come with extra sail or slightly cream laces.
The downsides are the synthetic usages on the 3 stripes along the sides, the blue back tab, and the tongue. The tongue seems to be backed with a felt-like material which sorta frays a bit which isn't really great. The tongue, though synthetic, doesn't seem to squeak when walking around like other tongues made of vinyl which is good, though this may happen as time goes on.
As a wide footer, what pleasantly surprised me is the wider toe box. For reference, it's a bit wider than the Forum and Superstar ADV (idk about regular Superstars). Definitely wider than Jordan 1's, 4's, and Dunks. Similar to Jordan 5's from memory but the HRLM might be slightly roomier than even those. These sit my feet flat and lower to the ground similar to Dunks which I prefer for casual use.
The cupsole apparently is an "updated" outsole on the Centennial Lo. I don't have a pair of those to compare but the outsole pattern is similar or the same from pictures of the Centennial Lo and on the Forums. The cupsole has a sailed or aged look.
The box is just a typical blue Adidas box but I appreciate the budget going into the actual shoes rather than the packaging.
I like these a lot, so much so that not only did I return my Dunks by You and a recent GR Forum pick up, I also doubled up on today's drop on Adidas confirmed. The quality is very good at $110 and my wide ass feet definitely appreciate the wider toe box. Definitely one of my favorite pick ups this year!

Got these off the SNS raffle and they arrived a couple of days ago.
The polyurethane coat is not heavy so the leather really shines. The white leather panels feel nice and soft to the touch - Definitely better than GR Adidas sneakers. Fairly thick leather panels relative to most sneakers. The suede toe panel feels pretty nice as well. The laces feel very thick and durable - definitely an underrated thing to consider in shoes. They come with extra sail or slightly cream laces.
The downsides are the synthetic usages on the 3 stripes along the sides, the blue back tab, and the tongue. The tongue seems to be backed with a felt-like material which sorta frays a bit which isn't really great. The tongue, though synthetic, doesn't seem to squeak when walking around like other tongues made of vinyl which is good, though this may happen as time goes on.
As a wide footer, what pleasantly surprised me is the wider toe box. For reference, it's a bit wider than the Forum and Superstar ADV (idk about regular Superstars). Definitely wider than Jordan 1's, 4's, and Dunks. Similar to Jordan 5's from memory but the HRLM might be slightly roomier than even those. These sit my feet flat and lower to the ground similar to Dunks which I prefer for casual use.
The cupsole apparently is an "updated" outsole on the Centennial Lo. I don't have a pair of those to compare but the outsole pattern is similar or the same from pictures of the Centennial Lo and on the Forums. The cupsole has a sailed or aged look.
The box is just a typical blue Adidas box but I appreciate the budget going into the actual shoes rather than the packaging.
I like these a lot, so much so that did I not only return my Dunks by You and a recent GR Forum pick up, I also doubled up on today's drop on Adidas confirmed. The quality is very good at $110 and my wide ass feet definitely appreciates the wider toe box. Definitely one of my favorite pick ups this year!

Came across another “special” Toyota owner super nice guy! I love his GR Corolla barely any miles on it, got it only $2500 over sticker!! already matte PPF thing is mean wish I could grab 2 of these engines and make a v6 and slap it in a Camry

I knew him from the Supra community but he’s doing work on the GR also. Not my car but it’s good to see what the stock fuel system is capable of

1st in index out of 188 drivers. GR Corolla beat the other D-Street cars (BRZs driven by top notch drivers) by almost 1.5 seconds in raw time. Not sure of mods on the Gr Corolla, but I'm assuming aftermarket struts and a rear sway bar change. Some good evidence this is a very capable car.

...and unstable bullets: a primer by a first timer.
photo album at the end
I recently inherited my grandfather's old hunting rifle (I know, this is the long range forum not hunting but bear with me). After disassembling and giving it a good clean, I began my research into this fine old firearm. I learned about the history of the .244 Rem cartridge and the decisions and occurances that led to its swift demise, only to be reborn under the name 6mm Rem. Unfortunately, despite being held by some as superior to the .243 win it remains almost obsolete today.
I read that due to the slower 1:12 twist rate of my particular rifle that it would fail to "stabilize" heavier bullets. I am newer to guns and brand new to bolt-action rifles and any distance beyond the length of an indoor range. With that, I also read that 80-85 gr bullets at most would perform well here and possibly some up to 95. What I didn't understand unfortunately was anything about how that stability was calculated, so despite having to order some pricey custom ammo thanks to the very hard to find cartridge that this beauty is chambered in, I managed to still order inappropriate rounds unbeknownst to me. Barnes 80 gr ttsx to be exact, and then I also stumbled across some 95 gr vmax in person and grabbed that as well. It wasn't until after my first trip to the range that I learned about bullet length and the true calculation, but off to shoot I went!
The range my friend brought me too is fantastic, and goes out to 600 yards with sensors and digital interfaces. Despite coming stocked with ammo that pencils out to roughly .77 SG at the muzzle of my setup, myself never having laid my hands on a rifle, and this firearm not having been touched or fired in decades - the results were far better than I could have hoped for and I am hooked. I couldn't be happier with it. After an initial bore-sighting and a couple rounds to zero, I had no trouble finding the center of the target.
This is not meant to be a testimony to any degree of accuracy of the gun, the ammo, my skill or lack thereof - just sharing my first experience and the joy it brought me to use my late grandfather's gun I never had the chance to talk to him about.
I took 5 shots at the 100 yard, then only 3 a piece at the 200 and 300 so I could advance to the 600 - I didn't shoot it much at these targets this first time but here is the full experience and result.
The only shange I made to the gun as I found it was to swap out the original weaver for a vortex crossfire II 3-9x40
100 (5) - just over 1 moa 200 (3) - 1.28 moa 300 (3) - 1.90 moa 600 (7) - 3.47 moa
After learning more about the ballistics I have ordered some rounds with Sierra 85gr spitzers and am headed back once those arrive to see how much of a difference a stable bullet makes! Sorry such a long post but thanks for reading, please enjoy some photos of the gun and results.
https://imgur.com/gallery/EQwfUVA