The new Sierra Reloading Manual (Edition VI) has introduced tested loads for IMR-4451 Enduron and Alliant Reloder 16 alongside IMR and Hodgdon 4350 loads in almost every suitable cartridge with a full range of bullets. (There is also a smaller number of Re23 data alongside the 4831s.) This allows a useful comparison on charge weights and performance between members of the quartet.
Having looked across a double figure number of cartridges, Sierra's maximum charge weights for H4350 and Re16 are invariably close. In some cartridges, the Alliant powder shows a marginally larger charge; in others marginally lower - we're talking 0.1 to 0.9gn differences, usally 0.5gn or less for same velocity loadings. In a few cases, Re16 allows the load to be increased to hit the next highest MV in the table, usually for those tables that are in 50 fps rather than 100 fps steps.
For the 6.5mm Creedmoor with 140/142gn (Sierra) bullets here are the four powders' listed loads:
Case: Hornady
Primer: Winchester WLR
Firearm: Universal receiver / 24-inch test barrel
IMR-4350 ................................. Minimum charge listed: 39.2gn (2,500 fps) ................ Maximum: 42.4gn (2,700 fps)
H4350 ................................................................................... Min: 39.2gn ........................................ Maximum: 41.9gn (2,700 fps)
IMR-4451 Enduron ........................................................ Min: 39.9gn ......................................... Maximum 42.9gn (2,700 fps)
Alliant Re16 ...................................................................... Min: 40.2gn (2,600 fps) ............... Maximum 43.5gn* (2,800 fps)
* The Re16 load shown to produce 2,700 fps MV, and therefore equivalent to the other three cartridges' maximum charge values, is 42.0gn
Interestingly, and to me a little surprisingly, the 43.5gn Maximum for Re16 exceeds that of Re17 (42.1gn / 2,800 fps).
Note, Sierra recommends that loads below its minimum values listed are not used.
In other equivalent cartridges, the pattern of the top same-speed loads being close between Re16 and H4350 continues although in a few cases the numbers are reversed with the Alliant grade being somewhere under a grain weight lower. Even within a single cartridge's (eg 6.5 Creedmoor) data-set, this may also apply to different bullet weights. (For Sierra's 130gn bullets, Re16 charge weight is marginally lower than H4350 for the 2,850 fps MV line - but again, Re16 gets a higher absolute maximum charge weight thereby increasing MV to 2,900 fps, 50 fps higher than those of its IMR and Hodgdon alternatives.)
Hornady's (Reloading Manual 10th edition, the most recent one) doesn't have Re16 in its Creedmoor tables as this manual was published a couple of years earlier than Sierra's, It maxima for IMR-4350, IMR-4451, and H4350 are:
IMR-4350 ................ 42.0gn (2,750 fps)
IMR-4451 ................ 41.3gn (2,650 fps)
H4350 ....................... 41.5gn (2,700 fps)
Note each powder's max is for a different MV, but H4350 is as for the Sierra manual at 2,700 fps albeit using a slightly lower charge weight.
6.5 Creedmoor
Hornady case
Federal 210M match primer
Remington 700 Custom 24-inch barrel
140gn ELD-M and 143gn ELD-X among other Hornady bullets.
I should have been range testing Re16 against H4350 this spring and summer, comparing an H4350 base-loading in a 7mm-08 F-Class rifle with the 160gn Sierra TMK against another 12 or 13 potential alternatives in terms of MVs and short-range groups. I got one test session in during late February which gave me the H4350 baseline and results for two possible replacements from Norma (N204 and URP) .... then the damnable Covid-19 appeared and 'my' bench equipped 100 yards range facility has been effectively closed since, maybe only now partially resuming but with all sorts of restrictions on booking and use.
