Lapua with supressor

[wboggs]

My buddy has a Sako .338 Lapua with a factory brake and a suppressor. We shot it today with both 250 and 300 gr factory Lapua ammo. Shoots 1 1/2" at 200 with the brake. Screw on the suppressor and we got 4-8" horizontal without any wind, vertical 1-2". In summary, accuracy went to hell with the suppressor. There are no signs the bullet is contacting the suppressor. The barrel is completely free floated and we took plenty of time between shots. Would appreciate feedback from you that have experience with this type set up. Also, suggestions for a starting place to make this rifle shoot.

 

[ShootDots]

I do not know about all the "tactical gadgetry" of rifles, such as a suppressor. However, a friend of mine uses one on his .308. He screws it on and off at will. If this be the case, I believe it would act like a "tuner" of sorts. If it IS acting in this fashion, that could be your source of inaccuracy. If I am not mistaken, there is no way to "tune" a suppressor. You may have to disregard it's use if there is no way around it's interference with barrel harmonics as it ill-effects the accuracy level of the rifle.

 

[Drop Port]

What brand is the can?

 

[jlow]

I agree with ShootDots – most likely harmonics. Of course, the obvious way around this if you reload would be to develop your own loads with the suppressor attached so that the rounds can be tuned to the rifle with the suppressor attached.

 

[wboggs]

Will get model # and manufacturer, hopefully tomorrow. The rifle is not in my possession.
Thanks
Bill

 

[Drop Port]

Generally screw on is the way to go for accuracy, although there are a few good quick mounting systems. In my experience a load that shoots well often shoots well with can on and have even seen loads tighten with the can. With a good can I've never seen groups grow as much as you are seeing. Thunder Beast Arms have been very consistent and are commonly used in precision rife matches. I have seen mounting systems and miss aligned baffles cause serious headaches.

 

[boltfluter]

+1 for dropports comments. I have 2 rifles with cans that I built and both are tack drivers. I think one key fact is that they both screw on. I have heard of accuracy issues with quick release mounts.

Regards, Paul

www.boltfluting.com

 

[mao0720]

I have a QD 30 cal can that I use on everything from 308 to 243 to 223 and I have not seen an ill effect on accuracy yet. I do get a point of impact shift between shooting with and without the suppressor, but accuracy is still great with it on and is frequently sub 1/2 MOA.

 

[Warren Dean]

Like several before have said, it's a harmonics thing.

Retune the load because it's pretty clear that it is on the edge of one node or another.

I shoot a Yankee Hill Phantom QD 7.62 on my 300 Win Mag Savage 110BA. The POI shift is about 1 minute between the can being on or off, but the precision is unaffected and hangs right at 1/2 MOA out to 900.

But.....I am running the Berger 230s at at a fairly docile 2890 fps .

I know several guys that seem to think that maximum velocity is the holy grail and load accordingly with lowered precision expectations for bragging rights on velocity. And they are all 338 shooters....go figure.

Running any bullet at the hairy upper edge is going to make it finicky and I suspect this is what your buddy is experiencing. Just revisit the load development with the can on and I'll bet that the difference between the two will diminish greatly.

 

[wboggs]

I plan to start the load development with modest R33 loads. However, I do not want to do that if there is a mechanical problem with the installation or the can itself.
I would like to thank all who have offered insights. Keep them coming.
Bill

 

[wboggs]

Details on Suppressor system : Yankee Hill Machine 3800 with QD mount system. Now we can get specific with your comments. Would also appreciate comments on the AAC Titan QD Fast Attach .338 LM with the Titan QD Muzzle Brake, both with Ratchet mount. Thanks Bill

 

[Drop Port]

If it shoots without it I would be looking at three things as a cause.

1 Did it come threaded or who threaded it, see some nasty run out on thread jobs.

2 The mounting system / brake, some systems are better than others. Does it shoot better without the brake.

3 Baffle alignment.

You can fine tune a load to the brake BUT it should shoot the same load fine with nothing more that POI shift.

If you are accuracy driven, Thunder Beast, my friends Sako shoot 1/2 MOA with box ammo and a little tighter with the can.

 

[4xforfun]

All the tuning in the world won't get rid of 8" groups at 200. What suprises me is that groups are horazontal !!

 

[wboggs]

My sentiments exactly. Bill

 

[Hotrod6.5]

New to the forum but I have been learning a lot. I use a Silencerco Harvester with direct screw on mounting. I cut my threads at the time I cut my crown with the bore running as close to zero TIR as I can dial it. I keep my pitch diameter as tight as possible for maximum bullet clearance. To keep my can from loosing during a twenty shot relay I use a belvue cupped washer compressed between my threaded shoulder on the barrel and the face of the can. Problem solved. My POI shifts down about 1MOA with my 6.5 Creedmoor 30" heavy Palma tube with the suppressor installed. Before I started using the belvue washer my suppressor would loosen up after 4or 5 shots and groups would open up big time. I use this suppressor on everything from a 20 Vartarg to the Creedmore and just change the threaded adaptor for the 1/2" and 5/8" threads. I love shooting with a suppressor and feel like it helps harmonic damping. I don't load hot but stop when I get good groups on my 400 yd range. I look for very low vertical and low std deviation. My accuracy load for my F-open 6.5 CM IS only 2765. My last relay shot at red castle gun club (Sand Springs OK)with this set up was a clean with 13x's at 600yds. Since this was only my third competition I was very happy and surprised but needless to say she shoots.

 

[idahoorion]

Hotrod 6.5

Is the washer you refer to commonly known as "crush" washer?

if you are only running it in the 2700's....do you need a new handle?
LOL

Idahoorion

 

[Warren Dean]

All the tuning in the world won't get rid of 8" groups at 200. What suprises me is that groups are horazontal !!

I don't recall seeing a reference to 8" groups. Is this correct, Bill?

 

[Hotrod6.5]

Hotrod 6.5

Is the washer you refer to commonly known as "crush" washer?

if you are only running it in the 2700's....do you need a new handle?
LOL

Idahoorion

No, a crush washer is a different animal. The Bellville Disc Springs are sometimes called a cup or spring washer. I got mine from McMasterCarr.com The ones I settled on are .035 thick with a ¾ OD with a 5/8” hole. These washers compress flat and after my suppressor makes contact with the outside lip it takes about one turn to bottom the can out. I tested the run out on a threaded spud on my lathe and as long as the washers are compressed till flat there is no run out. I place the opening of the cup toward the muzzle.
For me, trying to get maximum speed from any particular caliber after a good accuracy load is developed is not necessary. The little knob on top of the scope fixes low velocity anyway. This is also a good reason to build more guns. My current build is an Aleseo/Pierce Tube gun in 6.5X284 which will take the velocity up a notch from my Creedmoor. Also I make my own .264 BT bullets with a set of carbide Nemi dies. I make a 142.5 gr bullet with a 10 secant ogive with 1.325 long jackets. My dies will make flat base for point blank or BT for long range. I make BTs in this weight to keep my air gap at the point to one diameter (.260) At 2760 to 2780 FPS they shoot bugholes. Also I form Lapua 308 Palma brass for my Creedmoor which uses small primers and a small flash hole. I have no problem with ignition with regular205 Fed primers and H 4350. SD less than 10fps too.
BTW, my first name is Rod so hotrod6.5 was the best handle I could come up with.

 

[jcampbellsmith]

I only shoot my rifles with moderator/suppressor on. They are only fired at proof without the moderator.

http://www.thestalkingdirectory.co.uk/gallery/member-galleries/p2948-remington-700-sa-in-260-rem.html

Regards

JCS

 

[SDDasher]

New to the forum but I have been learning a lot. I use a Silencerco Harvester with direct screw on mounting. I cut my threads at the time I cut my crown with the bore running as close to zero TIR as I can dial it. I keep my pitch diameter as tight as possible for maximum bullet clearance. To keep my can from loosing during a twenty shot relay I use a belvue cupped washer compressed between my threaded shoulder on the barrel and the face of the can. Problem solved. My POI shifts down about 1MOA with my 6.5 Creedmoor 30" heavy Palma tube with the suppressor installed. Before I started using the belvue washer my suppressor would loosen up after 4or 5 shots and groups would open up big time. I use this suppressor on everything from a 20 Vartarg to the Creedmore and just change the threaded adaptor for the 1/2" and 5/8" threads. I love shooting with a suppressor and feel like it helps harmonic damping. I don't load hot but stop when I get good groups on my 400 yd range. I look for very low vertical and low std deviation. My accuracy load for my F-open 6.5 CM IS only 2765. My last relay shot at red castle gun club (Sand Springs OK)with this set up was a clean with 13x's at 600yds. Since this was only my third competition I was very happy and surprised but needless to say she shoots.

Good report; and good shooting.