High pressure warnings

Remember that these rifles were only proof tested based on the 144 gr NATO bullet, and even then the Proof testing was fudged to get them to pass.

I am no expert on pressures but listen to those with much more experience than I

It is not ideal to use heavier weight bullets.

Heavier bullets accelerate slower than lighter bullets. Slower bullets means less space behind them which means higher pressure, which means faster powder burn which means even more pressure.

There is s discussion about the 2A / 2A1's on another forum where Brian d**k* suggests that nothing other than NATO 144gr should be used - he had one to repair where someone decided to load up to M118 LR specs with a 175gr bullet and wondered why the bolt disintegrated.

*Brian (BDL Ltd) is possibly one of the most experienced armourers and repairers of LE's in the USA.

I misread his original post The Armourer . My apologies to you and yours.

It is interesting that you brought up the M118LR.

I have been using the updated M852 special ball ammunition to the original M118. It is handloads consisting of the 168grn BTHP, 41.0grns of IMR4064, and GM215M primers. I also use for the really long range stuff, the MK316 MOD O special ball. That consists of a 175gr BTHP,  41.7grns of IMR4064 and GM215M primers as well. Both rounds have been extensively used in my No4Mk1/2 with the 2A1barrel.  No noticable pressure issues,no blown primers,no case separation, and no issue with extraction of a spent round. I have witnessed on a few occasions, a primer that has backed itself out of the pocket from an undercharged round. That in conjunction with a light firing pin strike. 

I think that keeping the bullet velocity similar to that of the standard .303 is probably adviseable if using bullets of a similar weight.