Accuracy decrease with supressor on

[RockyRandy]

I shoot nothing but suppressed, I have always seen a 3" bullet drop when I put a can on verses no can.
This group is with a 136 grn lupua scenar 43.5grn of Stable 6.5 running at 2850 fps. Everything is happy with this load, but I have been trying to work up a load with 130 grn ELD-M and have been struggling trying to get it to group. I know I can get it there but it will take some tinkering and that's what I believe you are going to have to do with your load. I haven't experienced what your dealing with and hope I never do but one thing I know for sure is that I will never shoot another rifle without a suppresser on it do to the fact that I'm 80% deaf from shooting guns as a kid without hearing protection, You know 6'3" 180lbs and invincible, so I thought.

I posted this on another thread but you may try putting a tuner behind the can. I have never tried this but KSS had this pic on their ATS tuner page. I would check it with an alignment rod as you tune it just to be safe.

 

[RockyRandy]

I shoot nothing but suppressed, I have always seen a 3" bullet drop when I put a can on verses no can.
This group is with a 136 grn lupua scenar 43.5grn of Stable 6.5 running at 2850 fps. Everything is happy with this load, but I have been trying to work up a load with 130 grn ELD-M and have been struggling trying to get it to group. I know I can get it there but it will take some tinkering and that's what I believe you are going to have to do with your load. I haven't experienced what your dealing with and hope I never do but one thing I know for sure is that I will never shoot another rifle without a suppresser on it do to the fact that I'm 80% deaf from shooting guns as a kid without hearing protection, You know 6'3" 180lbs and invincible, so I thought.

 

[skipglo]

More than one Savage has had crooked threads from the factory, I think it happens from every factory but a bud had a Savage 338LM like yours that shot really well with no brake or can, put a brake or a can on and it was a 5-6 minute rifle. Tried to chase the thread and there wasn't enough left of the high side so cut and crown with good threads and it was easily sub minute again without the brake or can and WITH the brake OR the can. If you like the rifle I'd lose 3/4" of that barrel and get back to shooting.

Interesting!!!! But if the threads were crooked...would the brakes not be difficult to thread on? It should jam at some point "Methinks"!

 

[HSmithTX]

Skip, no, it is entirely possible to machine threads and the shoulder off axis with the bore and out of concentricity at the same time, on a lathe. It is 100% due to poor setup. To simplify that answer the threads can be out of alignment with the bore in a left/right/up/down ANGLE to the bore centerline as well as being off center rotationally. It doesn't take a lot of error here to cause issues. My bud's 338LM went from a complete pile of junk to a decent shooter just by removing the brake which surprised me because usually the crown is done in the same operation as the threading, so if the threads are off the crown is off too but in this case it was close enough to still shoot good groups. He wanted a brake and a can to spot impacts so when he took it to his smith he first tried to chase the threads and found out they were too far off to save so he lopped them off the barrel and set it up right, cut new threads and shoulder and it shot great with every brake afterwards. The can changed POI but groups were as good if not a little better. We shot it to a mile, once the dope was right it was relatively easy to shoot sub minute groups at the mile. I think it cost him around $225-250 all said and done, lots better than $1000+ for a rebarrel.

 

[QuietTexan]

Skip, no, it is entirely possible to machine threads and the shoulder off axis with the bore and out of concentricity at the same time, on a lathe.

You mean like every AK ever made?

But if the threads were crooked...

There are two general ways to install a barrel - dialed out end to end, or dialed out on the bore in front of the chamber. I have rifles made both ways by competent smiths and in my practical experience neither way is better or worse; I'm sure there are a hundred nuances as to why smiths choose a method to use most of the time.

But the same logic applies to muzzle threads. If the smith doesn't dial in the muzzle exactly and cuts threads the machine will still make a set of functional threads (not 3A but will let things screw on well enough), but they essentially point the wrong way.

If the guy running the lathe dials in on the outside of the barrel and not off the bore there can be a pretty significant difference there. If you've never seen a smith pin a bore or really dug into just how not-straight the barrel makers drill out blanks it's a crazy experience to realize how much the bore moves around inside the tube. Some are obviously better than others, but some mass produced tubes are really bad.

Cutting off-bore angle can stress and distort the crown and the thinner section of the barrel that was threaded (depending on bore to thread size relationship), and anything that impacts the bullet as it exits the crown is the worst kind of error to impart into a bullet's trajectory.

 

[Don Titus]

Yep its all harmonics. Spaghetti
sporter barrels thin and long will be more susceptible to harmonic waves and vibrations and weight distribution than short fat barrels.
This is a fact.

This a great thread. I just ordered a Banish 30 suppressor from Silencer Central for my Tikka T3X in 300 WM. The rifle came with a factory brake and I ordered the shorter 7" version which weighs 11.2 oz., so it probably on adds a couple of ounces more than the weight of the brake. After reading this thread, I'm a bit concerned about how it will affect accuracy ( w/brake it now averages about .5" with the Hammer 174 @ 3100 fps.). Sounds like at a minimum, I will need to adjust for a change in POI., or perhaps find another node (currently 76.5 gr. H4831SC).

Also, I recently saw an advertisement for a shim kit $24 for about 12 different shims) which is supposed to enable minor adjustments of the can to locate the "sweet spot". Has anyone tried this approach? No hurry on this end, as I have to wait 6-8 months for the bureaucrats to do their thing.

 

[QuietTexan]

Also, I recently saw an advertisement for a shim kit $24 for about 12 different shims) which is supposed to enable minor adjustments of the can to locate the "sweet spot".

This?

Accu-Washer® Muzzle Device Alignment System

Accu-Washer®: Perfect muzzle brake alignment with one shim. Eliminates multi-shim issues. Ensures accuracy and safety.

precisionarmament.com

Have used these for a long time to time muzzle brakes instead of peel washers, highly recommend them.

 

[Veteran]

This a great thread. I just ordered a Banish 30 suppressor from Silencer Central for my Tikka T3X in 300 WM. The rifle came with a factory brake and I ordered the shorter 7" version which weighs 11.2 oz., so it probably on adds a couple of ounces more than the weight of the brake. After reading this thread, I'm a bit concerned about how it will affect accuracy ( w/brake it now averages about .5" with the Hammer 174 @ 3100 fps.). Sounds like at a minimum, I will need to adjust for a change in POI., or perhaps find another node (currently 76.5 gr. H4831SC).

Also, I recently saw an advertisement for a shim kit $24 for about 12 different shims) which is supposed to enable minor adjustments of the can to locate the "sweet spot". Has anyone tried this approach? No hurry on this end, as I have to wait 6-8 months for the bureaucrats to do their thing.

You can fine tune the harmonics without shims, though its still a bit of trial and error. Put a tuner on your bbl., then the can. Then you just adjust the tuner to tune the bbl to the new harmonics, and keep your existing load.

That may cost $200 for the tuner, but you will spend a lot of time and trouble and ammo changing out shims and putting the can on and off that wont be needed w a barrel tuner.

Thats all for grouping/MOA.

You will always have to adjust for POI.

A bbl. tuner installed with a brake is shown below. Same configuration w a can instead.

 

[Don Titus]

You can fine tune the harmonics without shims, though its still a bit of trial and error. Put a tuner on your bbl., then the can. Then you just adjust the tuner to tune the bbl to the new harmonics, and keep your existing load.

That may cost $200 for the tuner, but you will spend a lot of time and trouble and ammo changing out shims and putting the can on and off that wont be needed w a barrel tuner.

Thats all for grouping/MOA.

You will always have to adjust for POI.

A bbl. tuner installed with a brake is shown below. Same configuration w a can instead.

Great info and adviceThanks!

 

[Don Titus]

This?

Accu-Washer® Muzzle Device Alignment System

Accu-Washer®: Perfect muzzle brake alignment with one shim. Eliminates multi-shim issues. Ensures accuracy and safety.

precisionarmament.com

Have used these for a long time to time muzzle brakes instead of peel washers, highly recommend them.

That's the one, glad to hear it works for you; have to decide between shims or a tuner as next post suggested.

 

[ObiWanKannoli]

Accu Washers are meant for timing a muzzle device. They are a good solution for timing a muzzle device to which a suppressor will be mounted because they generally maintain concetricity well. So, they don't make accuracy or precision better so much as they fix an issue induced by other methods of timing such as crush washers which are not concentric at all.

 

[skipglo]

Skip, no, it is entirely possible to machine threads and the shoulder off axis with the bore and out of concentricity at the same time, on a lathe. It is 100% due to poor setup. To simplify that answer the threads can be out of alignment with the bore in a left/right/up/down ANGLE to the bore centerline as well as being off center rotationally. It doesn't take a lot of error here to cause issues. My bud's 338LM went from a complete pile of junk to a decent shooter just by removing the brake which surprised me because usually the crown is done in the same operation as the threading, so if the threads are off the crown is off too but in this case it was close enough to still shoot good groups. He wanted a brake and a can to spot impacts so when he took it to his smith he first tried to chase the threads and found out they were too far off to save so he lopped them off the barrel and set it up right, cut new threads and shoulder and it shot great with every brake afterwards. The can changed POI but groups were as good if not a little better. We shot it to a mile, once the dope was right it was relatively easy to shoot sub minute groups at the mile. I think it cost him around $225-250 all said and done, lots better than $1000+ for a rebarrel.

Thank you Brother, I appreciate the info. I will have it looked at....I'm experiencing the same issue with 4 of these guns. Worth exploring for sure. I shot another brake Sunday....first shot was 6" low...after that managed a .250 GROUP with 4 rds. Got me scratching my head now....each shot 5 minutes apart in - 6 degree weather...so each shot...cold bore.. have a great night. And thanks again.

 

[Veteran]

Accu Washers are meant for timing a muzzle device. They are a good solution for timing a muzzle device to which a suppressor will be mounted because they generally maintain concetricity well. So, they don't make accuracy or precision better so much as they fix an issue induced by other methods of timing such as crush washers which are not concentric at all.

The way the shims or accu washers improve accuracy is that like a bbl tuner, you can use them to shift the weight distribution further out along the barrel. Thats what a barrel tuner does. When you twist it, each click it shifts a weight further in or out on the bbl. until it finds a harmonic node where the rifle groups well. Shims though, a more
crowbar, brute way of doing it shift weight along the bbl. if you hang a can or brake on the end.

It is feasible just more trial and error and work to get there.

Before installing a bbl tuner, I actually put a shaft collar around the end of my barrel and moved it back and forth to prove to myself it would work.

Then I spent the money on a more elegant solution.....the bbl. tuner.

 

[QuietTexan]

The way the shims or accu washers improve accuracy is that like a bbl tuner, you can use them to shift the weight distribution further out along the barrel. Thats what a barrel tuner does.

Yes sir, it's a valid way to do it. Moving weight forwards and backwards a precise amount of distance, doesn't matter if it's the tuner, the can, the brake, etc.