For those having issues getting their long contact patch type bucking (TNT or ML), flat or concave nubs (Prommy, ML Omega, etc) seated proper in certain barrels, consider the following.
From my experience, [pictured above] TNT and ML barrel have a longer hop opening or window. Allowing for the use of many of the longer type nubs available. Also note TNT is bridged at the rear.
However, [pictured below] TM, ORGA, Prommy, etc mimic the stock size normal window size. PDI uses an even smaller hop window. Thus, flat and concave nubs have to be cut to fit. With less contact patch affect.
Although some say smaller windows have better seal, better efficiency, but let's keep this on compatibility issues cause we all want to blast 46g out as far as possible.
So the consideration of barrel + nub + bucking combo is critical and also if your barrel is the stock type window, is the small gain in contact a benefit to you. As someone already pointed out the cylindrical type nubs are good up to and sometimes beyond 32/36g bbs, and have less margin of error when installing and performing, as well very consistent shot to shot (more on this later).
Also in the mix, keep in mind your barrel length and bore diameter, as it plays a role in fps and a factor in the resulting range.
Photo 1: TM barrel with ML Omega nub, although it looks as if it will fit, there is not enough space left for the bucking between the barrel window and nub.
Photo 2, TM barrel + ML Omega, picture does not show well, once the bucking is installed front of the nub gets hung up on the barrel and will become slanted.
Always try your new barrel + nub + bucking before installing into the upper as this will be hard to catch afterwards.
Photo 3: TM barrel with ML Omega cut to size
Photo 4: test, stays flat with consistent pressure
I will say this is enough to lift and over hop 46g easy and due to the longer contact patch it starts to become difficult to control and maintain consistency of lighter 25g/20g bb weights.
Photo 5: TNT barrel with uncut ML Omega, combo will also work with ML barrels.
As well due to the longer contact patch each turn on the hop dial adds much more pressure and fine tuning can be difficult. Some players and myself included, experienced on a certain setting being abit low while the next setting being abit high and hoping there was half turn option on the MWS hop dial.
This can be overcome by switching with the next bb weight higher or lower, resulting in many different weight bbs in your bag. As well due to GBBR temperature temperaments, you may be required to change bb weight with a drastic weather change or readjusting hop setting.
Also lower weights of around 25g become increasingly harder to use and the jump in increase per turn of the hop dial can be felt much more.
I like to put Teflon tape around the hop arm to minimize later movement.
Photo 6: TNT barrel + ML Omega + Laylax hop unit. Much more of a TDC affect as, hard to see in [photo 5] but due to the swing of the TM hop arm the placement of of the nub is alittle rear ward on the bucking.
Photo 7: TNT barrel + max size Prommy Nub, this will not work as the TNT barrel has a bridge at the rear.
Photo 8: ML barrel + max size Prommy Nub, this will work. However may be redundant as the BB sits somewhere underneath the middle, just a little behind the middle of the nub. The excessive long patch to the rear is likely a waste. You'll want to focus on a longer patch in front of the bbs path.
Photo 8: quick shot of nub types and what should be compatible. ML I key requires modding to fit.
Photo 9: other options to consider
I have not mentioned the differences in nub shapes and bucking shapes. As that's up to the user, the above is just want I found to work or not work. To hopefully give you some good ideas or save you some time and to also consider some of the side affects for certain modifications.
These would be primarily drop in/bolt on parts options asides from more custom rhops, etc.
As well TM vsr barrel have a different notch from TM GBB barrels. But GBB and vsr buckings are cross compatible.
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