Suppressors Suppressor speed increase

2

223ai

Gunny Sergeant
Full Member
Minuteman
Jun 28, 2006
1,091
15
Texas
#1
I spent some quality time on the range with my Omega 300 and my .308 today, and was too dumb to shoot without the can to answer my own questions, and search didn't help...so here it goes:

My barrel is a 10 twist finished at 20 inches. With my load of 45.0 grains of 4895, 155 scenars, and cci 200's, I was averaging 2910 fps with the can on. If I pull the can and rerun the load over my chronograph, can I expect a velocity decrease?

Thanks,
Josh
 
#2
Re: Supressor speed increase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JPipes</div><div class="ubbcode-body">
My barrel is a 10 twist finished at 20 inches. With my load of 45.0 grains of 4895, 155 scenars, and cci 200's, I was averaging 2910 fps with the can on. If I pull the can and rerun the load over my chronograph, can I expect a velocity decrease?

Thanks,
Josh </div></div>

Well, every rifle is different, so trying to answer your question is like trying to anticipate whether a woman will be mad or happy with you tomorrow afternoon.

But, generally....

Using a suppressor usually ADDS about 20 - 40 FPS due to a phenomenon known as "free bore boost."

YMMV
 
#6
Re: Suppressor speed increase

Lighten up, Francis. If you had the intelligence to read my original post, you would see that I flat out out forgot to run the load over my chronograph sans suppressor to test velocity changes...to put it bluntly.

Either way, I'll be back at the range in a few weeks to test POI shift and velocity changes without the suppressor. Should be interesting to see the differences. I've not heard of "freebore boost" and a quick google search gave me a lot of data to read through...thanks for mentioning it.

Best,
Josh
 
#8
Re: Suppressor speed increase

Thanks Jedi. I was up to 45.8 grains of 4895 with winchester brass at 2.805" LOAL, but saw too much pressure. My primer pockets were loose after the third firing, so I downloaded to 45.0 grains and switched to virgin Remington brass. I finally got it over the chronograph and was surprised at the speed.

I am actually using RG4895 milsurp powder that I got at Wideners. I bought 16 pounds of it, and wish I would have bought more...
 
#9
Re: Suppressor speed increase

Roger that mil surp 4895 is good to go
here are some of my loads
lapua brass OAL 2.820 45.6
Win Brass OAL 2.820 46.6

I never had any temp issues and my max load 48.4 OAL 2.920 Had av FPS of 3050 5 shots over a 35p
 
#11
Re: Suppressor speed increase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: long-shot</div><div class="ubbcode-body">Easy answer... NO you won't get any noticeable velocity increase. </div></div>

I have seen otherwise. Myself and several others get a noticeable velocity increase. Mine hovers around 60fps with the setup mentioned above. If I was running 2600 or more without the can, I would not consider it important, but since the added velocity with the suppressor gets me in the 2600 range out of an 18" barrel I think it is important. After a certain point, 40fps or so would not be a big deal, but on the slower end of the spectrum it can make a difference. For my short gun, depending on the pressure and temp, it can be the difference between staying supersonic at 1k. I havent, however, thought it important enough to measure on, say, my full length barrel 7wsm or 308.
 
#12
Re: Suppressor speed increase

I have (2) .30 cans. Neither give me any velocity increase.

I know of a few folks who thought their cans brought them increased velocities. In the end, they were not conscious of the fact that running a suppressor makes your barreled action heat up faster and get a lot hotter. They were cooking the rounds in the chamber. That chamber cooking accounted for all of their claimed fps increase.

I'm not saying that's the case with all suppressors, but mine offered none, and the few other brands that I tested out didn't have any either.

I'm glad that mine offer no boost. I have fewer things to think about when switching between suppressed and not suppressed ... the drop charts should be the same (accounting for any zero shift).
 
#13
Re: Suppressor speed increase

As usual I need to justify my statement. I haven't seen a "noticeable" difference in velocity. I have no idea if my velocity has gained at all. I shoot my .308 out to 800 yards routinely and make the same hits with the same dope with or without my can. I don't trust chronographs to begin with so I rely on my targets to tell me if my dope is right.
 
#14
Re: Suppressor speed increase

Generally, you will see an increase with suppressors. I nver beleived it myself until Murderman, DevL and I did some objective testing and found that in general, the suppressor added some velocity.

However, in one case, it actually decreased velocity.
 
#15
Re: Suppressor speed increase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: long-shot</div><div class="ubbcode-body">Easy answer... NO you won't get any noticeable velocity increase. </div></div>

See sig line.
 
#16
Re: Suppressor speed increase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: garandman</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: long-shot</div><div class="ubbcode-body">Easy answer... NO you won't get any noticeable velocity increase. </div></div>

See sig line.

</div></div>

If I plug in 40 fps more to my dope for 800 yards I get the following:

175 SMK
2730 fps
drop - 6.9 mils

If I shoot my regular data at 800 yards I get:

175 SMK
2690 fps
drop - 7 mils

That's less than 4" difference at 800 yards assuming you get the max velocity increase you mentioned earlier in this discussion. That's still in the 10 ring at a considerable distance for a .308. That qualifies for "No noticeable increase" to me. As an engineer by trade I can certainly see how a longer tube with an explosion behind it "might" add pressure and therefore velocity, and even so 40 fps sounds excessive so we can plug in 20 fps (the low end of your stated findings) and I don't even change my dope when using DTAC cards hence less than .1 mil.

I would happily shoot my rifle over a chronograph and we can compare and discuss how the results might actually affect bullet flight path but I already know that your numbers seem pretty high to me and even those won't affect the outcome of a match so why are we even giving a shit?

I however don't get any change of impact at this range so I'm not concerned, and say with great confidence that my suppressor (Cyclone K) has no affect on velocity.
 
#18
Re: Suppressor speed increase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: long-shot</div><div class="ubbcode-body"> blah blah blah. </div></div>

Every rifle is different, but free bore boost is real.

Several people on this forum have already posted that it DOES happen with their rigs, based on their chrono results. I've experienced it on mine, based on chrono results.

You claim your suppressor doesn't affect velocity on your rig.


Have you ever actually chrono'd your setup? Until you have, your just running your mouth, and continuing to validate my sig line.


We are NOT talking about PoI here, we're talking about velocity. Your mathematical "dopey" test is a hypothetical that doesn't necessarily translate into reality.


First rule, for when you find yourself in a hole: STOP DIGGING.

.
 
#19
Re: Suppressor speed increase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: garandman</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: long-shot</div><div class="ubbcode-body"> blah blah blah. </div></div>


</div></div>

Pretty confident I never said the above quote! Interesting rebuke to solid data though.
 
#20
Re: Suppressor speed increase

PM sent to garandman

I never posted "blah blah blah" at all so I would appreciate you editing your post. In fact I posted actual figures. I never said that a suppressor didn't add velocity. I said that a suppressor didn't add enough velocity to change a match or tournament score significantly. I shoot in matches quite frequently, do you? How do you score in those matches? What are your findings at range? I own a chronograph, but have lent it to a fellow shooting buddy for over a year because I find the readings only useful for load development. Until you prove your findings are more relevant than humidity, temp, and elevation I don't find the "increase" in velocity to be of this much debate.

yours,
jeff
 
#22
Re: Suppressor speed increase

garandmans reponse:

OP was NOT talking about changing PoI, or match score. I've shot plenty of matches, but that is irrelevant. Which is why I posted "blah blah blah" for your post cuz most of your post was off topic.

OP aksed aobut VELOCITY CHANGE. Got it? Velocity change.

WHich MANY folks, myself included, have found to be 20-40 FPS. Ands some 60 FPS.

Since you haven't chrono'd your gun, you can't really speak ON topic, but you didn;t let that stop you, for some reason.

My posts will stay as they are. YOU should edit out the off topic material in your psot.

G'day.
 
#23
Re: Suppressor speed increase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: long-shot</div><div class="ubbcode-body">I tell you what I'll head up to the range this week and shoot 2 5 shot groups at 700 yards with and without my suppressor. I'll post my results here. </div></div>


You mean you'll actually have some actual data to talk about what the OP asked about - velocity change at the muzzle with and without the can?

Gee, Wally, that'd be swell....

I suspect we'll NOT hear your actual chrono'd results, cuz I'm almost certain you'll have a 20-40 -60 FPS change with and without.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
Would you care to tell us all how far off my groups will be? My suppressor causes a .3 mil lower POI. I documented this in this post:

http://www.snipershide.com/forum/ubbthre...2528#Post962528 </div></div>

Start your own thread about PoI shift or bullet drop at range or whatever you want cuz THIS thread is about velocity change at the muzzle, with and without a can.

 
#24
Re: Suppressor speed increase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: long-shot</div><div class="ubbcode-body">garandmans reponse:

OP was NOT talking about changing PoI, or match score. I've shot plenty of matches, but that is irrelevant. Which is why I posted "blah blah blah" for your post cuz most of your post was off topic.

OP aksed aobut VELOCITY CHANGE. Got it? Velocity change.

WHich MANY folks, myself included, have found to be 20-40 FPS. Ands some 60 FPS.

Since you haven't chrono'd your gun, you can't really speak ON topic, but you didn;t let that stop you, for some reason.

My posts will stay as they are. YOU should edit out the off topic material in your psot.

G'day.

</div></div>


Nice. You post a private conversation publicly. Real upstanding thing to do.

Not that I mind, cuz I basically just said it publicly, above.

Its just REAL poor form on your part.
 
#25
Re: Suppressor speed increase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: long-shot</div><div class="ubbcode-body"> I don't find the "increase" in velocity to be of this much debate.

yours,
jeff </div></div>


Then exit the thread, cuz THAT is what the OP asked about.

It doesn't matter if you don't think that is not important enuf to be talked about.
 
#26
Re: Suppressor speed increase

Back to the subject at hand:

I have two cans ( SRT Arms 300 Win mag and a TBAC 30P). My log book shows that Aug 2008 my SRT arms can gave an average velocity that was 5fps faster than without it. The TBAC can in March 2009, showed similar results with less than 10fps gain on my 24" Bartlein barrel with a 308 shooting 155gr over Varget.

Just my experience.

Josh
 
#27
Re: Suppressor speed increase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: J. A. Hamilton</div><div class="ubbcode-body">Back to the subject at hand:

I have two cans ( SRT Arms 300 Win mag and a TBAC 30P). My log book shows that Aug 2008 my SRT arms can gave an average velocity that was 5fps faster than without it. The TBAC can in March 2009, showed similar results with less than 10fps gain on my 24" Bartlein barrel with a 308 shooting 155gr over Varget.

Just my experience.

Josh </div></div>


ACTUAL experience is helpful. Thanx you.

Do you know the overbore of your can?

The free bore boost concept is based on the notion that with a suppressor, there is still pressure behind the bullet after leaving the friction caused by the inside of the bore. Pressure + reduced friction = x FPS free bore boost.

Theoretically, a larger overbore would create less free bore boost.

Unfortunately, ballistics is more like an art than a pure science. Which is why the OP's question can really only be answered in terms of a specific rifle / can / load / atmosphereic conditions, etc.

 
#28
Re: Suppressor speed increase

i, guess we, can all post ours findings and we build up data site, we all can see and come up with a conclusion.
i'll be chrony with and without and will post my findings soon.
with can add load, suppressor model, type of rifle, field conditions, etc and see.
 
#29
Re: Suppressor speed increase

i finaly got a chance to go to the range and chrono my load and i saw a speed increase with the can on, i tested 4 different loads my load where:

168smk
lc case
rl15 43.1
wlr
@2.800"
avag spd change between both were 29ft/s

168smk
lc case
rl15 42.5
wlr
@2.800"
avg spd between was 54ft/s

168smk
lapua case
rl15 43.1
wlr
@2.800"
avg spd between was 54.4ft/s

168smk
lapua case
imr 4895 42.2
wlr
@2.800"
avg. spd between was 6.7ft/s

at the end looks to me that the powder brand was the factor that made the difference between having the can on or off. since on my test the imr 4895 show very little change between them.
my rifle is badger m2008 gen 2, schnider m24 1-12tws, aics 2.0, jewell trigger, tigershark supressor.
condition were 50degrees, rainy day, wind 3-5 12oclock.

hopes this helps
 
You must log in or register to reply here.

Similar threads

T
Truing Ballistic Calculator, Velocity Errors?
Replies
8
Views
459
chevy_man
C
N
.17 HMR - fps all over the place
Replies
10
Views
495
carbonbased
carbonbased
R
Chrono readings and Strelock.
Replies
12
Views
484
CK1.0
CK1.0
J
6 GT Load Suggestions & Suppressor Pressure Signs!?
Replies
31
Views
911
Conrad
C
Rodney65
Velocity differences between 6.5cm brass brands
Replies
5
Views
251
Rodney65
Rodney65
Top Bottom
Back
Home
Forums
Merch
Alerts