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Old 01-18-2020, 02:13 PM   #1
meltingfeather
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Default Suppressed vs. Unsuppressed Velocity

So another thread got me interested in this topic recently and I had the opportunity to collect some data today.
I needed to fire form 50 cases for my new APR
6.5 Creedmoor
20" barrel
Barrel was brand new.

Unfired Peterson brass full length sized, trimmed, neck turned, reamed, faced, chamfered, and deburred. The necks all seemed to have adequate tension-- I did not size them, which may add some scatter to the data. the SD is pretty high for both sets, but it also took a few rounds for the barrel to settle in, which added to the SD.

129 gr. SST
42 gr. of RL-17

I didn't Q/C the charge weights like I normally do since I was just fire forming, but I dialed the first one and all were thrown with a Redding BR-30, which is very consistent normally.

I shot groups of 5, starting unsuppressed, then adding the can, then back, through 50 rounds. Chrono'ed with a Magnetospeed. The first round with the can didn't read properly because I had too much gap. Round 40 failed to feed because I accidentally pulled a 7mm button through it after the neck got dinged and didn't resize the neck far enough down to feed.

One small set of data and I didn't know what to expect, except that some folks on here said the can would add velocity. I grouped "shot pairs" even though they weren't shot that way because it seemed to present the comparison in the best way. Scatter plots didn't really say much.
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Last edited by meltingfeather; 01-18-2020 at 02:16 PM.
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Old 01-18-2020, 02:22 PM   #2
meltingfeather
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Old 01-18-2020, 02:26 PM   #3
meltingfeather
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Ignoring the first 5 pairs changes the data:
Suppressed:
Avg. - 2,746 fps
SD - 18 fps

Unsuppressed:
Avg. - 2,730 fps
SD - 22 fps

If anyone has ideas about different looks at the data or experiments to run, I'm all ears.
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Old 01-18-2020, 02:31 PM   #4
meltingfeather
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I was gonna be pretty surprised if there was a substantial gain-- just seems like too much volume in a can to continue to push the bullet in a meaningful way, but there does seem to be some effect... worth about 1/2" of barrel length!
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Old 01-18-2020, 11:20 PM   #5
ahlongslide
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Interesting! I did the same test with my Specwar back in the day and got 2% velocity increase. But it wasn’t as detailed of an analysis. Yours is way more legitimate
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Old 01-18-2020, 11:27 PM   #6
MUZZYSLINGR
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Very interesting study you did there. Thanks for posting it.


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Old 01-23-2020, 04:45 PM   #7
Conrad
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Good test. Thanks. Pretty similar to what I typically see.
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Old 01-23-2020, 06:35 PM   #8
duckmanep
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good info
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Old 01-23-2020, 06:40 PM   #9
sierracharlie338
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Pretty similar to data I’ve seen in person over the years as well.


Sierracharlie out…
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Old 01-23-2020, 07:07 PM   #10
ORIONTHEHUNTER
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Did you notice any difference in accuracy. I know on a couple of my rifles they shoot tighter groups suppressed
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Old 01-23-2020, 08:30 PM   #11
meltingfeather
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Quote:
Originally Posted by ORIONTHEHUNTER View Post
Did you notice any difference in accuracy. I know on a couple of my rifles they shoot tighter groups suppressed
I was fire forming and had the Magnetospeed strapped to the barrel, so not really shooting for groups.

That's a decent idea for when I do get a load worked out though-- I'll remember that. It plays into another topic that came up recently which is the difference (if any) between brands of suppressors with respect to accuracy. Your idea adds a little different flavor.
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Old 01-23-2020, 08:38 PM   #12
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I have always wondered this.Thanks for posting.

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Old 01-23-2020, 08:41 PM   #13
John316
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Did you notice much change in point of impact, with / without suppressor?
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Old 01-24-2020, 07:47 AM   #14
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Thanks for sharing! And I'll echo John316's question. I'm going to pick my suppressor up this afternoon and I want to know what I'm in for!
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Old 01-24-2020, 08:16 AM   #15
cblackall
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Quote:
Originally Posted by John316 View Post
Did you notice much change in point of impact, with / without suppressor?
There will be a shift in POI. How much depends on several things. Your barrel contour, length of barrel, caliber, which can you’re running, etc. Two of the same rifles with the same suppressors side by side may have differently POI changes. If you’re running a good setup, this shift should be repeatable though. I run an Omega direct thread on multiple rifles. They’re all zeroed with the suppressor, and I have no issues with POI shift when swapping the can back and forth. I can’t remember what my actual shifts were prior to zero (it’s written down somewhere), but they were all low. Roughly somewhere between 2-4”~ at 100 yds on average if I remember correctly.
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Old 01-24-2020, 09:16 AM   #16
rosco11
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Quote:
Originally Posted by Saltyag15 View Post
Thanks for sharing! And I'll echo John316's question. I'm going to pick my suppressor up this afternoon and I want to know what I'm in for!
Congrats! Wish it was easier but when you use em...They are worth the wait!

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Old 01-24-2020, 09:22 AM   #17
hollywood1981
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My POI did not shift that much shooting suppresed. 1/2" at most on my 308. Like stated above it will shift
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Old 01-24-2020, 09:22 AM   #18
meltingfeather
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Default Suppressed vs. Unsuppressed Velocity

Quote:
Originally Posted by John316 View Post
Did you notice much change in point of impact, with / without suppressor?
In this case it was about 2-1/2” low and right at 100 yds. with the can. Consistently through multiple removals and replacements of my Rugged Razor 7.62 with a quick disconnect system.
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Old 01-24-2020, 10:06 AM   #19
trophy8
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Try again in the summer! Mine has really varied.

I have had a couple rifles not like the can at all. Lighter barreled hunting rigs.

Dang good data table though. Looking forward to more!
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Old 01-24-2020, 10:41 AM   #20
ORIONTHEHUNTER
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Quote:
Originally Posted by cblackall View Post
There will be a shift in POI. How much depends on several things. Your barrel contour, length of barrel, caliber, which can you’re running, etc. Two of the same rifles with the same suppressors side by side may have differently POI changes. If you’re running a good setup, this shift should be repeatable though. I run an Omega direct thread on multiple rifles. They’re all zeroed with the suppressor, and I have no issues with POI shift when swapping the can back and forth. I can’t remember what my actual shifts were prior to zero (it’s written down somewhere), but they were all low. Roughly somewhere between 2-4”~ at 100 yds on average if I remember correctly.
I run the same setup and have identical results
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