Sellier & Bellot (Five types):
I've had some down time so I've spent hours measuring rim thickness on .22 ammo.
I have 101 types of ammo now for testing. I decided to measure rim thickness on Sellier & Bellot and see if they could be improved. I tested three types of S&B three years ago with poor results, so I thought I'd test them again now. This would validate the data I got before, if it still shoots poorly. I batched 1160rds (of 2230rds) of Standard, HVHP, Subsonic HP, Club, and Short. Last time I tried Standard, High-Velocity HP and Subsonic HP, with very poor results - 10rd groups at 50m of 72mm, 35mm and 27mm respectively. Shooting them batched by rim thickness to within .001" did see minor improvement, but not enough to matter. From what I've seen, I think three-thou is a more realistic increment in terms of measureable difference at the target, but the caliper measures in thou so I'll stay with it.
I scrubbed the bore of the RPR spotless beforehand, then fired three 5rd groups with CCI Std to set a benchmark, 19mm, 17mm and 16mm, not bad from a clean bore. After 267rds of S&B, I shot another six 5rd groups of CCI Std to confirm the rifle was not at fault, with a best of 17mm.
I fired 267rds of S&B on Tuesday arvo at 50m when the wind was very calm. The best were a pair of 21mm 5rd groups with S&B Subsonic, one of 21.5mm with HVHP, one of 22.5mm with Club, and one of 27mm with Standard - I can't say anything good about S&B .22 ammo at all. Any slight improvement may well be due to simply shooting 5rd groups instead of the 10rd groups I shot last time. They weren't accurate enough to really see a trend in rim thickness except with S&B Subsonic, which seemed to group better with .036"-.037" rims. Subsonic was also the best when I tried them before, and is the only S&B .22LR I can recommend trying. These are the results in my Ruger Americans and RPR, I'm sure there are other people that great excellent results from this ammo.
There's a possible trend with Standard at .034"-.035", but it's still 2MoA ammo. Consider that I shot an initial 6rd group of "randoms", one at .031", two at .032", two at 0.34", and one at 0.41" - into a 29mm group, only beaten by the 27mm group (batched to .035") . The .041" round was very hard to chamber, and to open the bolt after firing, but fired normally.
- SandB 1.JPG (99.96 KiB) Viewed 9849 times
- SandB 2.JPG (69.13 KiB) Viewed 9849 times
Although the Subsonic is the most accurate of all of these, it also has the greatest variation in rim-thickness, from .032" to .038".
Standard is the worst by a good margin, which makes sense when only 25% of the ammo has a consistent rim thickness. Subsonic HP, Short, and HVHP all have 40% with the same thickness. Club is better at 55%, but doesn't shoot great regardless.
I batched 590rds of Standard, then I only did 300rds of Subsonic as the variation was even worse than the Standard. I only did 100rds of the Club and Short, and only 70rds of HVHP. Even 100rds shows Club is clearly made to a tighter quality control.
The S&B Shorts were a surprise, S&B claim them to be 920fps in a 600mm barrel, but in my 450mm barrel I made 641fps, they dropped 300mm low at 50m. The slowest and quietest .22 ammo I've ever used. I'll have to group it at 25m rather than 50m as I think 50m is outside its potential use. I only fired 15 of these as it was just wasting them at that distance.
I also measured velocities (as specified in 600mm barrels by S&B):
Subsonic HP 40gn HP at 310m (1017fps) - actual 18" RPR is 1055fps +4%
Standard 40gn RN at 325m (1066fps) - actual 18" RPR is 1116fps +5% (all went supersonic)
Club 40gn RN at 325m (1066fps) - actual 18" RPR is 1100fps +3% (most went supersonic)
HVHP 38gn HP at 375m (1230fps) - actual 18" RPR is 1251fps +2%
Short 28.1gn RN at 280m (920fps) - actual 18" RPR is 641fps -30%
I thought it'd be good to have rim thicknesses recorded to refer to later to see if there is a definite relationship to accuracy, so I've measured over 8000rds so far. Not so much for batching, more to have a measure of their quality control, so some of them I'm only measuring one or two boxes.