The Firing Line Forums

Go Back   The Firing Line Forums > The Hide > The Art of the Rifle: General

Reply
 
Thread Tools
Old January 13, 2013, 04:11 PM   #1
Colorado Redneck
Senior Member
 
Join Date: January 6, 2008
Location: Northeast Colorado
Posts: 1,119
Silencer on a skinny factory barrel rifle

Does installing a can on a skinny barrel rifle impact the accuracy of that rifle? I have read that the POI can be altered, which is no big deal. The barrel harmonics are the biggest concern. If the weight of the can plus the "leverage" on the tip of the barrel changes harmonics, then it would become a project to find another load that produces acceptable accuracy?

If anybody has any experience with this, please weigh in. I have a CZ American in .222 Reminton that has been a booger to get figured out, but it seems that the problems have been ironed out. I am looking at a YHM 3200, to quiet the muzzle blast for prairie poodle popping.
Colorado Redneck is offline  
Old January 13, 2013, 06:50 PM   #2
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,204
Anything you hang on a barrel will change the frequency it vibrates at. Doing so may or may not change its accuracy. But the only thing that'll change is the barrel's resonant frequency and its harmonics; they'll still stay fixed for every shot fired regardless of the loads power; lower frequency for flimsy barrels, higher frequency for stiffer ones.

There's no accuracy difference between whippy, skinny barrels and stiff, thick ones. And many times a short, skinny barrel will be stiffer than a longer, thicker one for the same cartridge. If a load won't shoot accurate in a barrel, it's not how stiff or rigid the barrel is; something else ain't right.

Glue a large nut or two to the barrel just behind the muzzle then see what happens. Move the nuts back and forth to see if there's any difference. That's cheaper than a muzzle brake. You can accomplish the same thing by changing powder charge weight to make bullets exit at a different point on the muzzle axis vertical swing to improve accuracy.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master
Bart B. is online now  
Old January 13, 2013, 10:06 PM   #3
Colorado Redneck
Senior Member
 
Join Date: January 6, 2008
Location: Northeast Colorado
Posts: 1,119
Thanks, Bart---You hit right on what I was thinking. If the harmonics change due to the added mass of a silencer, then perhaps a new load would have to be developed? I normally enjoy that kind of stuff, but right now, the components are in short supply, and I am really limited on the powder that is good for this gun.

I guess, considering that it might take 6 months to get the paperwork handled (or a lot longer) that powder might be available to us loaders by then.

Thanks again for your comments.
Colorado Redneck is offline  
Old January 14, 2013, 07:02 AM   #4
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,204
What powders do you have now? IMR4198 was a benchrest winner decades ago when the .222 Rem was "the" cartridge to win benchrest matches. H322 is also an excellent choice.

Changing charge weight does the same thing as as adding weight or moving it at the muzzle end. All both do is change the point where the bullet exits the muzzle as it whips up and down vertically. It's cheaper to change the charge weight than how much weight's on the muzzle or where it's at. Besides, a weight on the muzzle end needs to be moved if another load's used, so I think it's best to just change charge weight and/or powder type.

In the following burn rate chart, item 70 through 74 all all excellent for the .222. Use stick/extruded powder for best accuracy; ball powder's never been popular for best accuracy in any rifle cartridge.

http://www.hodgdon.com/burn-rate.html

That YHM 3200 at $500.00 is probably going to be a waste of money anyway. If you cannot get the barrel to shoot well with a different load, I doubt it'll do any better with that silencer on its muzzle. And what if it's not the barrel's problem? Something about the reloads may be the cause; tools, setup, component choices. And, just maybe, it's neither the rifle or the ammo that's at fault.

One thing to check; does the stock's fore end touch the barrel at any place? If so, that's guaranteed to be an accuracy detriment.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master

Last edited by Bart B.; January 14, 2013 at 08:34 AM.
Bart B. is online now  
Old January 14, 2013, 06:35 PM   #5
Colorado Redneck
Senior Member
 
Join Date: January 6, 2008
Location: Northeast Colorado
Posts: 1,119
The best powder so far is IMR 4198. The accuracy issue turned out to be a problem with neck sizing only. When starting out to find an accurate load, the Nosler 40 BT with 21 grains of 4198 was shooting good. At that time I was using new brass that I had passed through the full length die. Experimented with the COAL and was getting an occasional 1/2 inch group at 100 yds which is about as good as I can do anyway. Then things started getting wierd. Long story short, after doing some research in this forum, and reading other sources, it occurred to me that the issue might be that I had begun reusing my brass and the once fired brass was neck sized only. As best I can remember, the accuracy seemed to fall off about the time I started reusing that brass. I got a Hornady headspace gauge and with some experimenting the accuracy has improved to where it was at first. So at this time I am optomistic that the gun and the load are matched well enough for prairie dogging.

As for the suppressor, I don't expect that to improve accuracy, Bart. I am looking for experienced shooters that can attest to the fact that even if the can does shift the POI, the basic accuracy potential of the rifle does not diminsh after mounting the silencer. The purpose of the silencer is to decrease the report so I can shoot next to some rural residences without becoming annoying to the locals.

Thanks for the burn chart info. I will look into that directly.

Last edited by Colorado Redneck; January 14, 2013 at 06:42 PM.
Colorado Redneck is offline  
Old January 14, 2013, 08:40 PM   #6
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,204
When a weight's put on a rifle barrel at the muzzle, the barrel whips at a different frequency and harmonics for each shot. That extra weight makes the frequency lower. If it changes such that the bullet's leave while the muzzle axis is on the down swing, accuracy will be compromised. Slower bullets will leave at a lower angle, faster ones at a higher angle.

Best accuracy happens when the opposite happens. Slower bullets leaving at a higher/greater angle are compensated for their drop. Faster ones won't drop as much down range so their leaving at a lower angle doesn't cause a problem. This is the reason why the Brit's .303 SMLE's were so accurate at ranges past 500 yards with ammo having big muzzle velocity spreads.

So, I think your accuracy will change; maybe better, maybe worse.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master
Bart B. is online now  
Old January 14, 2013, 11:30 PM   #7
Colorado Redneck
Senior Member
 
Join Date: January 6, 2008
Location: Northeast Colorado
Posts: 1,119
Thanks for your comments, Bart. I did look at the burn rate chart, and may try some different powders when the panic buying dies down and they become available again. H322 looks interesting.

And your comments about the outcome of mounting a silencer and accuracy, I was thinking what you said, that the results might be better or worse. Well, the shooting club we belong to sells silencers, so tomorrow me and the better half will go punch some holes in paper and then discuss cans with the fine folks that run the place.

Enjoyed your input!
Colorado Redneck is offline  
Old January 15, 2013, 03:07 AM   #8
ATCDoktor
Member
 
Join Date: December 24, 2006
Posts: 67
With regards to suppressing rifles with "skinny barrels", I can offer you the following information based on my own experience:

The rifle in the picture below is a Remington model 7 youth model with a standard factory "sporter" (read Pencil) barrel.



With respect to "skinny barrels and suppression, the absolute first thing you need to determine is whether or not your muzzle diameter is large enough to support threading to a pitch of 1/2X28 and leave enough meat on the barrel to provide enough shoulder for your suppressor to "index" upon.

Without a "square" shoulder to index the can on baffle strikes are almost assured. Absent sufficient shoulder you also run the risk of the muzzle protruding too far into cans "blast chamber" causing carbon buildup on the exposed threads seizing the can to the barrel.

If your muzzle diameter will support threading but insufficient shoulder you have two options:

1. Cut the barrel back to a point where there is sufficient diameter for the required shoulder or:

2. Choose a fast Attach can that uses a Flash Hider or Muzzle Break attachment for the can, have your barrel threaded "long" and have the mount index on the muzzle.

No shoulder is required in option 2.

Option 2 is the route I took with above pictued Model 7. I went that route because I didn't want to cut several inches off the barrel to support having the shoulder:



In the above picture you can see the exposed threads behind the suppressor mount allowing for the mount to be "run" all the way down against the muzzle.

To some it may be unsightly but my kids don't seem to notice:





Accuracy has not been an issue with respect to teh can being indexed on the muzzle and with 40 grain ballistic tips and a standard charge of WC844T this riifle will have all rounds touching at 100 yards.

The suppressor I use on all my 223/556's is an AAC M42000 and it's the one shown on this rifle.

The M42K is somewhat heavy coming in at at 17.5 ounces (without the mount) and on this thin barreled rifle all that weight causes a 7 inch POI shift at 100 yards (from an unsuppressed zero).

That shift is repeatable with boring regularity with removing and replacing the can.

With regards to continued accuracy between suppressed and unsuppressed groups, there is no difference between the two.

Groups suppressed mirror those of the unsuppressed rifle, again, with boring regularity.

I will share that it has been my experience (with a properly threaded barrel and indexed can) there is no detriment to accuracy with respect to adding a suppressor.

If your rifle grouped well prior to using a can, it should continue to group well when suppressed.

If it doesn't then there is a problem with how the barrel is threaded/how the can is mounted.

At times I have noticed a small "increase" in accuracy and I have rifles whose groups (with pet loads) tighten somewhat when the suppressor is attached but not significantly so.

Groups tighten on my rifles (that display this trait while suppressed ) on the order of about 10%.

That said, I have never had a barrel that I considered inaccurate shoot markedly better with a suppressor attached.

I hope this tiny bit of info coupled with what Bart B shared has helped in some way.

If youhave anymore questions, feel free to ask.

Dr.

Last edited by ATCDoktor; January 15, 2013 at 03:19 AM.
ATCDoktor is offline  
Old January 15, 2013, 09:29 PM   #9
Colorado Redneck
Senior Member
 
Join Date: January 6, 2008
Location: Northeast Colorado
Posts: 1,119
Exactly the kind of input I was searching for, ATCDoktor. In looking further into the internet, there are some good vidoes and various articles/threads in which the opinions mirror what you and Bart have provided.

I have a varmint barrel 22-250 that is deadly (when I git'er done) and I am thinking maybe that is a better candidate for the can. I don't have a bunch of dollars to invest in this project, so the YHM 3200 looks affordable, and from the feedback on the internet they seem to be good units. Not the best, but good.

Whatever decision I make, you and Bart provided great info. Thanks to ya both!
Colorado Redneck is offline  
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 09:47 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.07982 seconds with 9 queries