View Full Version : Ops 15th shift
First, I am not going to defend my groups here. It was 100 degrees at the range with no shaded shooting position and a wobbly rest. Attack the groups if you must.
Rifle & can after shooting the first groups.
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/IMG_1615Small.jpg
Targets were 7" tall shoot-n-see. Optic was a 1.5x Compact ACOG.
The first pic is approximately 10 rounds of each of the following (from left to right) shot from a "rest" at 50 yards.
Black Hills blue box 75 grain
Prvi Partisan M193 55 grain
Wolf 55 grain steel case
Federal 55 grain XM193
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/IMG_1617Small.jpg
The second pic is approximately 5 rounds of each fired without the suppressor mounted. After I shot the first group of Prvi, Wolf, and XM (you can see those groups just above each shoot-n-see on the Wolf and XM) and noticed they weren't printing in the black, I fired 5 more rounds of each holding the tip of the triangle at the base of the shoot-n-see. Those are the groups you actually see on the Prvi, Wolf, and XM targets, with the BH target being shot holding center of the black.
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/IMG_1620Small.jpg
I would estimate the Wolf, Prvi, and XM shift to be approximately 8-10 MOA to the 12 o'clock, and the BH shift to be approximately 4 MOA in the same direction.
None of this is intended to be scientific in any way, just sharing my results.
Derek_Connor
08-06-07, 13:09
Very interesting.
I also have a OPS 15, on a 12.5 barrel. I'll have to redig my pictures, I did an informal 5 round x 4 shot string with the can off/on. Looking hard for those pics to see what the shift was...
Eventually I'll go back and see if I can shoot from prone to tighten up the groups and shoot a gridded target to better document the MOA shift.
Do you have any way to attach a more magnified optic??
To be more consistent, and give really solid results, I would suggest using match ammo.
I'd do the following if I wanted to get good usable data:
1) Zero the rifle without the suppressor on.
2) Print the best group you can with match ammo @ 100yds using a more "precise" magnified optic and no suppressor.
3) Install the suppressor and shoot again, from the same batch or box, on a 1" grid target.
My speculation: The ammo selection, ambient heat, "thin" barrel, and suppressor conspired against you in accuracy.
I'm just not interested in all that science.:D
I went to the range to zero the gun with the can on it with the ammo I'd using if hunting/fighting. I only printed the rest to get an idea if it would hold a close enough zero for training and competing, and it will. I thought I'd check to see what it does with the can off, and fortunately the ammo I want to have the slightest shift, does.
Beyond that my interest completely falls apart.
Something like a 4+ MOA shift would piss me off enough to get interested. :p
Something like a 4+ MOA shift would piss me off enough to get interested. :p
As I said, it's a non-issue for me. I'm not expecting great consistency out of a .625" dia. barrel, and this gun is really only ever intended to be fired with the can on. Interestingly, and what I was most wanting to check, the cheapest ammo shoots to virtually the same POA as the expensive stuff.
I'm going to order one of the muzzle break mounts from ADCO and I'll re-zero then. Maybe I'll be interested enough to play around more. I have a 3x Compact ACOG mounted on another gun, but in order to test it out I'd have to zero it to this gun, and then re-zero on the other gun. Yawn.:o
The 100 degree heat had alot to do with reducing my interest as well.
...and this gun is really only ever intended to be fired with the can on....
That's how I zeroed my 10.5" Noveske, with the intention that the can would be on it.
I have not yet check the zero shift. :o
Derek_Connor
08-06-07, 15:43
I have not yet check the zero shift. :o
Christ, I couldn't agree more.
Im too lazy to find the picture and search the Archive on TOS. It was my first range trip with the rifle and did the experiment to figure out what the shift was roughly so I could answer the question when asked. So much for keeping my results...
I rarely shoot my 12.5 rifle unsuppressed:
http://img502.imageshack.us/img502/4184/49713211eq0.jpg
The only time I take the can off is to new shooters who haven't seen the performance of a unsuppressed/suppressed rifle back to back.
And with the aimpoint that is now on the rifle, im not too concerned about 2moa, 4 moa, 6 moa shifted within the ranges im geared to shoot with this rifle
With my vast personal experience of owning ONE suppressor and shooting it on 4 different uppers, and knowing a couple of other guys who have suppressors... I'll make a few observations.
1) Zero shift is not a big deal as long as it's repeatable.
2) All cans will cause a shift in zero, unless it's just a fluke with that can on that weapon. It's just a matter of hanging weight on the end of a barrel. A lighter weight suppressor on a stiffer barrel would, in theory, make for an almost unmeasurable zero shift. I'm sure that's the "magic" behind why Surefire cans supposedly cause very little zero shift - lighter overall weight than most cans and telescoping back over the barrel moving the suppressor's center of gravity farther back...
3) Stainless steel flexes a LOT more than 4150 of similar contour. My suppressor weighs something like 26 oz. When I first got it, I shot it on one of Denny's "recon" barrels which is a fairly lightweight 16" stainless barrel. I got about 7-8 MOA to 6 o'clock shift. Put the same can on a 14.5" LMT M4 barrel on the same day with the same ammo and got about 1 MOA (or less) to 6 o'clock. Stainless Noveske 16" medium contour shifted about 3 MOA to 6 o'clock. And my CMMG 14.5" M4 barrel shifts about 1-2 MOA to 6 o'clock. All are/were repeatable, so I just had to know where the zero was going to go with the can on a particular carbine and adjust accordingly.
BTW, the M4 barrels are not the heavy "SOCOM" contour. Just standard lightweight under the handguards.
Rob - Even with your "pencil" contour barrel, I'd bet that if you sandbagged it and put a higher powered optic on it, you'd find that it will shoot smaller groups with the suppressor attached simply because the added weight at the muzzle decreases inconsistent barrel "whip".
I know it's capable of smaller groups as I've shot smaller groups with a 6933 without the can. I'm not terribly worried about the group size as I know it was operator (and weather) induced on that day.:D
With my relatively heavy SpecWar2 on the 10.5" CL MRP barrel I get about 1 MOA shift to 6 o'clock.
The same can on my fluted SS 14.5" WOA barrel gives me about 5 MOA shift. I've mounted both the old and new style BiLocs on it and the shift was consistent (it's a SBR lower) regardless of the mount.
welchtactical
08-20-07, 07:10
RobS: How does that flashhider mount work without the can? What about price? I need to meet you over at Markham and shoot that beaut! I'm doing the SBR thing right now, and with the short little barrel I know I'm gonna need a can! What's the price on that can? I'm going to have to hold off for a while on it, but one it is on the list.
Your barrel should be checked as well. Its not uncommon for Colt barrels to have bores as much as 7 thousandths off center. A perfectly concentric bore plays a significant factor in minimizing POI shift with a suppressor. If you can remove the barrel and send it in, we can tell you how concentric it is.
I have a 15th model as well, on a 16" gov't middy barrel (Sabre). I zeroed it with the can off at 50 yards (with irons), checked it on the 10" 200 yard steel (ding ... ding ding ding), put on the can and still hit it. Shooting for groups on paper at 100/50, I can't shoot well enough to notice a POI shift.
Once I'm finished moving and find a new range I'll try a more organized test on paper, but it'll only be with irons/4moa Aimpoint.
Bigbore - didn't some of your testing show that the flash hider mounts increased the dB on the cans by a small amount?
I'm using the regular 2-port brake, and after months of being ambivalent about it, I've really started to like it. It works really well with my mid gas, M16 carrier, and standard buffer.
Ron from Ops sent me a "used" muzzle break mount to try out in lieu of the A2 flash suppressor mount that ADCO sent with the can. I just got back from the range testing out the new mount. The difference was HUGE. Virtually no shift this time at 50 yards. I used a Leupold 3-9x optic and a bi-pod this time so the groups are slightly better (I'm not used to magnified optics and bipods, I need work). Pics to follow, but I would call the shift virtually nil at 50 yards now.
In other news, Black Hills 75 grain is well worth the cash. I would say it groups half to a quarter as tight as all the others I tried.\
One note. While the brake did appear to greatly improve the POI shift with and without the can, it is HUGELY louder, even to the shooter. and with XM193 it is loud enough that I would not want to shoot it.
Which creates the conundrum; the brake offers the least shift, but is essentially useless (to me) without the can, meaning that it's only useful with the can on. So it's usefulness is somewhat questionable IMHO. It is supposed to better protect the baffles, however, so I suppose it's worth it in that respect.
Pics to follow.
Which creates the conundrum; the brake offers the least shift, but is essentially useless (to me) without the can, meaning that it's only useful with the can on. So it's usefulness is somewhat questionable IMHO. It is supposed to better protect the baffles, however, so I suppose it's worth it in that respect.
Pics to follow.
Just shoot suppressed and don't worry about it. ;)
Interesting thread. I am willing to be that the majority of mass produced barrels are not perfectly centered (as Steve pointed out).
I have done some POI shift testing with my SF 556K and a Noveske 18" barrel and found almost no POI shift.
C4
Interesting thread. I am willing to be that the majority of mass produced barrels are not perfectly centered (as Steve pointed out).
I have done some POI shift testing with my SF 556K and a Noveske 18" barrel and found almost no POI shift.
C4
In this case I'd bet it is because the brake is the first baffle in the system and baffle placement and distances are critical. The first baffle is absent when using the FH.
Updated pics. Again, no appologies for my ability as a shooter. Running a magnified optic and bipod and trying for the best possible accuracy is very new to me as I'm generally content if I can hit a 6" steel at whatever range I'm engaging from and do so as quickly as I can. I certainly didn't take the time I should to try for groups in this test. I think you'll be able to tell the potential of each ammo type, and pick out the shooter errors. Each group was 10 shots. With all but the Barnaul, I'd call anything outside the 10-ring a flier, and with the Black Hills I'd call anything outside a 1" circle a flier (shooter error).
Since people keep asking....
I fired 30 shots of XM193 to get the scope on paper (scope is turned sideways, took me a couple of tries to figure out how to adjust for that), and then 10 shots of Black Hills to get zeroed. After that I shot the suppressed groups, BH & W first, then reload (I only had two 20-round mags with me) & shoot XM & Prvi, then reload and shoot B. I then let the gun cool enough to remove the suppressor, and fired 10 rounds of XM to heat the barrel back up, then followed the same shoot/load schedule above. Without a temp sensor I guesstimate that the barrel was kept as close to a constant temp as I could.
After all of this, my conclusion is that the muzzle brake mount definitely makes for less of a POI shift than the A2.
This was my first time shooting the gun with the brake mounted but without the can. The brake is LOUD, especially so with the XM193, even with my Sordins on. If I was going to be shooting just milspec ammo with only the brake on I would double-up on plugs & muffs. It was borderline painful to shoot (and probably affected the unsuppressed XM groups because of it to some extent). Because of this, I found an interesting conundrum; if you want to shoot the gun both suppressed and unsuppressed and see the least amount of POI shift, you need the brake, but shooting unsuppressed with the brake can be borderline intolerable, making the A2 a much better choice.
For me, I only ever intend to shoot this particular rifle suppressed. That's in fact the whole purpose for this particular rifle. In which case it really doesn't matter which mount I use, except to say that the brake allegedly both better protects the baffles and provides better sound suppression than the A2 mount. The other school of thought would be that even in my previous test the shift was acceptable for the range at which an 11.5" barrel AR would be effective, so the A2 is certainly serviceable if the user needs to have both suppressed and unsuppressed capability. For me, I'll keep using the brake on this gun since it stays suppressed, and I've mounted the A2 on my other 6933 just in case I ever want to put the can on it. I'd like to try the 3-prong mount I see on ADCO's site now, but not bad enough to pay for one.
It does bear mentioning that the A2 mount that I received with my can sells for $75, and the brake mount sells for $185. I am unsure if this savings was reflected in the price I paid for the can or not, but it's somewhat of a moot point now as Ops at least sent me out a free muzzle break mount after seeing the first post in this thread.
Thanks again to Ops for all the help, and hopefully the new results are more in line with what they would expect to see.
The ammo used
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/IMG_2527Medium.jpg
The gun (with suppressor and without)
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/IMG_2531Medium.jpg
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/IMG_2537Medium.jpg
Suppressed groups
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/IMG_2532Medium.jpg
Unsupressed groups
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/IMG_2538Medium.jpg
Thanks for sharing your experiences, Rob. It is interesting to see the difference between the brake and the A2.
When hanging any weight on the end of the barrel all bets are off on possible POI shift, but my personal experience with the Ops brakes/cans is that the shift is minimal. I use the brake and have no need to shoot the rifle without the can. I've never tried the A2 though, so I really appreciate you posting your findings.
Take care,
Mark
Rob_S - were you shooting under overhead cover?
I'm still trying to figure out why my brake seems variably obnoxious from one day to the next, even with the same ammunition. Five more inches of barrel probably helps me quite a bit, though.
fivepointoh
12-10-07, 12:55
Rob, looks good.
Looks like in the 2nd time out it just shifted down and to the left just a tad. Seems more than acceptable to me.
Then again I'm not allowed to have NFA goodies here in Illinoisistan but threads like this are making me prepared for the move and NFA heaven :p
Get some vids if ya can.
Rob_S - were you shooting under overhead cover?
Sorry, just noticed this question...
No, no overhead cover.
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