Here's some testing I did a while back.
- 24" Barrel
Mountie- 20" Barrel
- 16" Barrel
Fedral 550 Bulk Pac
k ammo, 36 grains HP bullet, copper "plated"
39A : Average velocity 1263 fps (Highest was 1283, lowest was 1237)
Mountie Average 1254 fps (hi 1297, low 1230)
39TDS Average 1251 fps (high 1292, low 1216)
Notes: claimed velocity on box says 1280. This ammo shoots well in a wide variety of my rimfires, including autoloaders. The accuracy is very good in all of my Marlins.
Aguilla SE Subsonic
38grains lead hollow point
39A average 984 (high 1000, low 937.2)
Mountie average 994 (high 1023, low 984)
TDS average 1007 fps (high 1024, low 993)
Notes: This ammo has proven to be accurate in a wide variety of my rimfires. Only Match ammo has surpassed it in guns that shoot it well. It does NOT cycle any of my autoloaders. On most days this ammo will produce the best groups. Today it was true in my 39A and Mountie. Interestingly the 16" Barreled 39TDS produced the highest Velocity with this ammo.
CCI CB Longs
29g RN lead
39A (it was hard to tell these even when off in this gun) 677 avg (681 high, 668 Low)
Mountie 675 avg (720 high, 636 low)
TDS 668 average (674 high, 652 low)
Notes: Only the TDS (1/2" @ 25 yards) and my Single Six shoot this what I would consider "well". The Mountie shoots it OK (~1" at 25 yards). Most of my rimfires do NOT shoot this well. It is very quiet in long barrels.
CCI Mini Mag 40g
copper coated, solids
39A 1255 avg (1272 high, 1230 low)
Mountie 1225 avg (1243 High, 1191 low)
TDS 1221 avg (1244 high, 1202 low)
Notes: Of my three 39's the Mountie shoots this the best. It is a little less accurate than the Fedral Bulk at more than twice the cost so I rarely use it.
, RN lead 40g (more than 20 years old, probably closer to thirty...)
39A 1230 avg (1242 high, 1214 low)
Mountie 1203 avg (1216 high, 1178 low)
TDS did not shot.
Notes: Shoots a little dirty. Mountie shoots these very well.