Just got my first can (TBAC Ultra 7) and took it for a spin today at the range. I had no idea what I had been missing all these years and don't see how I can ever shoot un-suppressed again.
However, I noticed what I thought was odd behavior when I started shooting my handloads suppressed. So I was shooting my 6.5 Creedmoor (TL3 w/Proof CF 24" Sendero) with my go to handload of 42Gr H4350 (143 ELD-X) which averages around 2740fps with historically no signs of pressure what so ever. I had recently done a barrel swap so I ran about 6 rounds of this load down the tube un-suppressed to re-zero with expected results. Expected normal velocities were there as well as sub MOA grouping with no signs of pressure.....perfect. Screwed on the new can and went through a 5 shot string in about 2 mins. Not rapid fire by any means. Shot #1 displayed same behavior as un-suppressed as far as velocity and no signs of pressure. Shot #2 showed a decrease in velocity by about 40 fps but still no signs of pressure. Shot #3 was low velocity and sticky bolt lift. Shot #4 was still down in velocity and borderline heavy bolt lift. By Shot #5 velocity was still down over 30 fps and was definitely a heavy bolt lift.
Did this same exercise after the ceasefire (about 10 min break/cooldown) with a slightly lower charge weight I had loaded for some foulers at 41.7 Gr H4350. Same behavior as noted above. First shot was right at my expected Avg velocity with no pressure. Then as my string progressed, my velocity went down and the signs of pressure went up. Ended up with heavy bolt lift and obvious ejector marks on my last couple rounds and at about 40fps lower than avg.
@Zak Smith - I saw in a previous post regarding a rise in pressure when shooting suppressed you said "Your chamber probably has a tight neck or throat and when the increased carbon builds up from the suppressor backpressure, it increases peak pressure due to less clearance". This makes sense to me and could quite possibly be the culprit but would this still apply if I am not seeing the decreased velocity and increased pressure on the first shot after the suppressor has been idle for 5-10 mins? If I let it sit for a while and then start a new string the first shot always seems perfectly fine but as the string progresses so does the pressure and the velocity decreases.
Do I need to allow more time between shots? I know after each shot there is a ton of smoke (feel like there is a more appropriate word than smoke but brain dead at the moment) that is coming back out the chamber between rounds. Does this need to dissipate before chambering and firing another round?
Overall the accuracy and group size was still great with the suppressor. As expected the POI was slightly off but in my case only about an 1 inch to the right and 1/2 inch low. My main concern is when doing future load development I'll start getting signs of pressure (ejector marks, sticky/heavy bolt lift) pre-maturely as well as having a large ES (due the velocity drop) on each charge weight that may skew the results when the same load un-suppressed wouldn't.
Hoping you more experienced and undoubtedly smarter shooters can shed some light on what i'm observing on my end.
However, I noticed what I thought was odd behavior when I started shooting my handloads suppressed. So I was shooting my 6.5 Creedmoor (TL3 w/Proof CF 24" Sendero) with my go to handload of 42Gr H4350 (143 ELD-X) which averages around 2740fps with historically no signs of pressure what so ever. I had recently done a barrel swap so I ran about 6 rounds of this load down the tube un-suppressed to re-zero with expected results. Expected normal velocities were there as well as sub MOA grouping with no signs of pressure.....perfect. Screwed on the new can and went through a 5 shot string in about 2 mins. Not rapid fire by any means. Shot #1 displayed same behavior as un-suppressed as far as velocity and no signs of pressure. Shot #2 showed a decrease in velocity by about 40 fps but still no signs of pressure. Shot #3 was low velocity and sticky bolt lift. Shot #4 was still down in velocity and borderline heavy bolt lift. By Shot #5 velocity was still down over 30 fps and was definitely a heavy bolt lift.
Did this same exercise after the ceasefire (about 10 min break/cooldown) with a slightly lower charge weight I had loaded for some foulers at 41.7 Gr H4350. Same behavior as noted above. First shot was right at my expected Avg velocity with no pressure. Then as my string progressed, my velocity went down and the signs of pressure went up. Ended up with heavy bolt lift and obvious ejector marks on my last couple rounds and at about 40fps lower than avg.
@Zak Smith - I saw in a previous post regarding a rise in pressure when shooting suppressed you said "Your chamber probably has a tight neck or throat and when the increased carbon builds up from the suppressor backpressure, it increases peak pressure due to less clearance". This makes sense to me and could quite possibly be the culprit but would this still apply if I am not seeing the decreased velocity and increased pressure on the first shot after the suppressor has been idle for 5-10 mins? If I let it sit for a while and then start a new string the first shot always seems perfectly fine but as the string progresses so does the pressure and the velocity decreases.
Do I need to allow more time between shots? I know after each shot there is a ton of smoke (feel like there is a more appropriate word than smoke but brain dead at the moment) that is coming back out the chamber between rounds. Does this need to dissipate before chambering and firing another round?
Overall the accuracy and group size was still great with the suppressor. As expected the POI was slightly off but in my case only about an 1 inch to the right and 1/2 inch low. My main concern is when doing future load development I'll start getting signs of pressure (ejector marks, sticky/heavy bolt lift) pre-maturely as well as having a large ES (due the velocity drop) on each charge weight that may skew the results when the same load un-suppressed wouldn't.
Hoping you more experienced and undoubtedly smarter shooters can shed some light on what i'm observing on my end.
