View Full Version : Muzzle velocity with a suppressor.
6.5 Creedmoor, 140gr Beger Hybrid. 2800 FPS. It always shoot really well with 1,099 rounds through it. Finally got a TBAC 30P-1 and I lost 75 FPS.
Everything was low with the can on. Can off, back to normal.
Can someone please explain this to me!
XC700116
11-10-2015, 19:36
Did you check/re-zero with the can on? typically they will cause a POI shift
Shawn, Yes. Can on, all low out to 1,000. Can off, all good with regular DOPE. I had 5 targets out, 279-555-674-775-1,000.
With the can on, I had to adjust the speed from the regular 2,800 FPS, to 2,725 FPS to get center hits.
Travis, No. Don't feel like I needed one with having great drop Data with Stu.
Great-Kazoo
11-10-2015, 22:41
ALL suppressors will give some POI shift. Direct thread or muzzle brake mount? I zero any suppressor ready long gun with can on. Can off i get from 1.5 - 4" POI difference. How are you "adjusting" your speed, By powder charge? Sorry not familiar with that term, unless it's muzzle velocity you're talking about with different charge weights.
XC700116
11-11-2015, 07:24
Damn, I kinda want to get the chrono on that now just to see, I haven't seen any deviation in my dope with or without mine on, zero of course changes even on my 260 with the truck axle barrel.
Jim, he's referring to re-truing his dope with the can on and back calculating his MV. Same load, same Rifle, only difference is the can.
Zach I'm assuming you reconfirmed your dope without the can the same day or at least relatively recent to account for atmospherics and barrel condition.
If anything I'd expect to see a slight (maybe 20fps) increase in MV with the can, although I haven't really seen anything significant with mine.
SuperiorDG
11-11-2015, 08:11
Strangely enough saw this today.
http://www.guns.com/2015/11/10/how-do-suppressors-affect-ammo-velocity-video/?utm_campaign=trueAnthem:+Trending+Content&utm_content=564326c404d3013cdbcb8e9b&utm_medium=trueAnthem&utm_source=facebook
How low at a grand?
Exactly 1/2 a mill.
7 mils without can.
7.5 mils with can.
Like has been said, POI shifts (and down) are not uncommon. Unless you are verifying with a chrono, you are doing it backwards. My MVs go up a tad with the suppressors mounted. My .260 barrel is axle-ish and short and I get a very slight shift up. With the thinner barrels, they are generally down a tad.
Like has been said, POI shifts (and down) are not uncommon. Unless you are verifying with a chrono, you are doing it backwards. My MVs go up a tad with the suppressors mounted. My .260 barrel is axle-ish and short and I get a very slight shift up. With the thinner barrels, they are generally down a tad.
How am I doing it backwards?
I got the can. I put can on said rifle. I re zeroed the Rifle at 100 yards. 5 shots just over .300".
My old DOPE is to low with can on. It's NOT POI. The only way I can get center hits, is to change my velocity from 2800fps to 2725 fps. How is this a POI problem?
Also Markco, my barrel did come off a truck.
Check dope at a couple other yardages like 300 and 600 to make sure it is off.
How am I doing it backwards?
Unless I misunderstood, you are adjusting velocity in the ballistics software to match what you are seeing on target...Correct?
You need to know your muzzle velocity, not guess it based on software. When the MV is known and the software does not match the bullet trace, you have two options...change the BC or adjust the drag model. A suppressor can change harmonics and MV, those are factors you need to account for and true the software to meet real world conditions.
Then again, you could have just been shooting into a headwind. :)
Unless I misunderstood, you are adjusting velocity in the ballistics software to match what you are seeing on target...Correct?
You need to know your muzzle velocity, not guess it based on software. When the MV is known and the software does not match the bullet trace, you have two options...change the BC or adjust the drag model. A suppressor can change harmonics and MV, those are factors you need to account for and true the software to meet real world conditions.
Then again, you could have just been shooting into a headwind. :)
Muzzle velocity was spot on. Measured in actual drop in inches at distance, without the can. It has been spot on for 1100 recorded rounds.
No head wind.
Check dope at a couple other yardages like 300 and 600 to make sure it is off.
I did. 279-555-674-774 and 1k. All low. Even at 279, just hit bottom edge of a 4" plate.
I blame the bourbon. But I get what your saying Zack what Bullet are you shooting ?
When was the last time the can was cleaned , carbon build up will make the can heavier and the POI change will change . Just like tuning a barrel with one of the tuning weights .
I blame the bourbon. But I get what your saying Zack what Bullet are you shooting ?
140 Hybrid
When was the last time the can was cleaned , carbon build up will make the can heavier and the POI change will change . Just like tuning a barrel with one of the tuning weights .
It's a brand new can. Not even 100 rounds yet.
When out today. I was just smart enough to leave my chronograph at the house. The whole reason I was doing this today. Ugh. Idiota!
Anyway, didn't bring alot of ammo. Confirmed a good zero at 100 yards. This was at 698 yards. The bottom group was with my usual 2800fps and the top was 2725.62058
After I seen the 2725 was now HIGH, I began to kick myself for leaving the chrony at home. I had 6 rounds left and shipped them to 1245 yards, just because. 62059
Guess I need to go back out with the proper equipment.
You've got a dead target at 1,245 yards. Your my hero. It seems like your screwing up your cause and effect.
You've got a dead target at 1,245 yards. Your my hero. It seems like your screwing up your cause and effect.
Care to help with suggestions?
I only use a chrono to check ES/SD. I could not give a shit about what it says for velocity. It is just a rough guess anyway.
Get a good solid zero for whatever range you are going to use then check at distance. However many clicks it takes to get your data to jive with what the bullet says it is actually going is how fast it is actually going.
Nice shooting at 1245 dude. That is some solid shooting for sure.
Care to help with suggestions?
Your so far past my skill and equipment level that I won't be helpful. That's some fine shooting. It just doesn't follow that dispersing the gas after exiting the tube would effect velocity.
Zack does not have his head completely up his ass. He's a solid shooter with a good understanding of the mechanics.
Zack, 1/2 mil is obviously a lot to attribute to shooter error, even one like you. ��
Any chance ammo temperature is a factor? Did you test with Stu with warm ammo and shoot with the can with colder ammo?
As Hose said, forget the chronograph. Re-run your test with Stu, or do it yourself using the data you just collected. Figure that you could be responsible for .2-.3 mills on a bad day.
Is your super secret squirrel range at the same altitude as canyon city?
Nothing else changed other than adding the can ?
Nothing else changed other than adding the can ?
And my attitude cause I thought I was finally cool...
Was just talking to Spdu4ia, and it just occurred to me that last week was a change in lot #s for the powder.
Could that do it?
I have a name homo
Are you saying your name is homo? Your lack of proper punctuation has me confused...
Not an unknown happening Varget is famous for it . Have seen it with SC as well . Tweek your load to get the velocity back .
Thanks everyone for all the input. I appreciate it.[Beer]
XC700116
11-12-2015, 21:25
Was just talking to Spdu4ia, and it just occurred to me that last week was a change in lot #s for the powder.
Could that do it?
Oh yeah, that could definitely do it. Could throw your load out of it's happy place and your SD/ES could grow, or shrink, or not.
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