The Firing Line Forums

Go Back   The Firing Line Forums > The North Corral > Lock and Load: Live Fire Exercises

Reply
 
Thread Tools
Old August 23, 2014, 09:59 PM   #1
Bennyfatsack
Member
 
Join Date: August 11, 2014
Location: NSW Australia
Posts: 77
Rest on barrel or stock changes point of impact greatly

Hi, surely others have encounted this before, but for my self shooting for over 25 yrs only just encountered this scenario last week when sighting in a new el'cheapo mossberg .22 plinkster. Was sighting a new nikko sterling in on the rifle, sighted roughly at 40yrds, with a bipod,had average 1" to 1 1/2" group after 50 or so rounds, bit of cold wind picked up, and i was already happy enough with sighting so sat in car and rested barrel on mirror and continued shooting out the last of the ammo I bought with me, only to find my groups blew out to 3"+ and nearly on average 4" high???? Had me scratching my head, proceeded to inspect scope, rings, screws etc figured I must have bumped or hot scope when I hopped in the car, proceeded to resight to 4" high but still had loose groups, really getting annoyed now, opened car door and repositioned now resting stock on door sill, and bang what do you know 4" low and groups tightened up again, would not have thought so much difference in both accuracy and point of impact between resting on barrel or stock. Repeated this over and over and was doing same, would not have thought a .22 would have been affected so much. Anyone else encountered this problem or can explain, I figure it must flex the barrel or something to do with harmonics??
Bennyfatsack is offline  
Old August 23, 2014, 11:56 PM   #2
jeager106
Junior member
 
Join Date: November 24, 2006
Location: N.E. Oh.
Posts: 527
Even a bit of up pressure on the bare barrel changes p.o.i.
It's not harmonics, it's up pressure.
jeager106 is offline  
Old August 24, 2014, 12:08 AM   #3
nazshooter
Senior Member
 
Join Date: November 7, 2008
Posts: 151
I've seen something similar. I have a Kel-tec su-16 which has a for end that folds down into a bipod which is attached to the barrel. I don't recall the groups opening up like that but the POI shifted by several inches at 50 yards.
nazshooter is offline  
Old August 30, 2014, 08:47 PM   #4
Crusty Deary Ol'Coot
Senior Member
 
Join Date: November 19, 2009
Location: Deary, Ideeeeeeho
Posts: 522
Well, I don't worry about this with my .22 Clark Custom 77/22 even though Clark tightly fit the stock to the barrel, simply for the reason that I am not hunting game with this rifle. Shooting mostly paper with this rifle, I really don't care where on the target the group forms, as long as that group is small.

However, for all my hunting rifles, bolt action or single shot, because I am very concern with first shot Point of Impact, all such rifles are floated and if the stock is wood, it is glas bedded.

Quite a few years back, My sons and I were hunting rock chucks/ground hogs in the scab rock country of Eastern Washington state.

The oldest son was shooting a RUGER 6mm heavy barrel which was quite accurate.

He was missing. Hitting high. Picked a solid rock face and took a few shots and sure enough high.

The problem was he had mounted a bipod to the front sling swivel stud and the weight of the rifle put a lot of pressure on the barrel with the bipod out near the end of the stock.

Working up loads, the bags would have been further to the rear when compared to the bipod and for that reason would decreased the pressure of the stock against the barrel and therefore not show the problem seen on the hunt.

The rifle went home, I glas bedded it and floated the barrel and there were no more such issues.

Now, it is said by some that a rifle shoots better with some upward pressure exerted by the stocks forend on the barrel. This may be true, however I have never seen a rifle shoot worse when floated and most shot better.

Now if a person is shooting some type of bench rest competition, and it has been found that their rifle shoots better with some measure of stock to barrel pressure, fine as very likely before shooting for score they will be allowed to shoot some "sighters" and then adjust for the current conditions.

However with a hunting rifle, no sighters are allowed and the first shot better be on the money.

Therefore, a floated barrel GREATLY decreases the possibility of humidity, temperature, soft or hard rest, position of the rest or bipod or any other outside influence affecting point of impact.

So, my hunting rifles are floated as standard procedure!

Crusty Deary ol'Coot
Crusty Deary Ol'Coot is offline  
Old August 30, 2014, 09:38 PM   #5
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,038
The reason that happens is the barrel and stock start vibrating as soon as the round fires and before the bullet clears the muzzle. Those vibrations bounce the stock and/or barrel away from the hard surface they're against. So the barrel points somewere else than it does when it or the stock doesn't rest against a hard place when the round's fired.
__________________
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 offline  
Old August 30, 2014, 10:39 PM   #6
JohnKSa
Staff
 
Join Date: February 12, 2001
Location: DFW Area
Posts: 18,434
Quote:
Those vibrations bounce the stock and/or barrel away from the hard surface they're against.
Exactly correct. You want to avoid placing the gun in contact with something hard/unyielding. It will bounce away from the hard surface during discharge resulting in inconsistent point of impact.
__________________
Did you know that there is a TEXAS State Rifle Association?
JohnKSa is offline  
Old August 31, 2014, 04:57 AM   #7
Bennyfatsack
Member
 
Join Date: August 11, 2014
Location: NSW Australia
Posts: 77
Great feed back will make myself more aware of what barrel contacts, explains a lot of unexplained misses over the last 25 yrs, and it's as simple as that.
Bennyfatsack is offline  
Old August 31, 2014, 05:14 AM   #8
Crusty Deary Ol'Coot
Senior Member
 
Join Date: November 19, 2009
Location: Deary, Ideeeeeeho
Posts: 522
As John and Bart indicate, it is poor practice to EVER rest a firearm solidly and directly against a hard service. Rather let the rifle rest on a hand or hat or??? which is in contact with the hard surface.

However, this is a .22 rimfire being talked about here and as such there will be a minimum amount of reaction between the hard surface and the rifle when compared with a harder recoiling firearm.

Float that barrel.

Crusty Deary Ol'Coot
Crusty Deary Ol'Coot is offline  
Old August 31, 2014, 12:11 PM   #9
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,038
But wait! Others think otherwise. Even .22 rimfire barrels suffer from it.

Al Freeland, decades ago top ranked smallbore rifle shooter, came up with a method to "tune" rimfire barrels with screws 90 degrees apart at 4:30 and 7:30 on the clock to the barrel from the fore end tip. Remington put that bedding/tuning system in their first 40X rimfire match rifles. What a joke that turned out to be. Tested in machine rests free from human intervention and holding variables, they could be tuned quite well. Slung up in position in shooting positions had all that external force applied differently from shot to shot. People soon learned to back those screws out and totally free float the barrel so it was free from fore end bending caused by position variables of the shooter. They're items 45 through 48 in the following parts diagram:

http://www.americanrifleman.org/wp-c...ingtonm40x.pdf

I had one years ago that shot very well after epoxy bedding the receiver, but those screws were removed after testing ammo for accuracy with different forces on the barrel.

For those interested, here's the directions for using them.

http://www.rimfirecentral.com/forums...d.php?t=167446
__________________
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.; August 31, 2014 at 12:29 PM.
Bart B. is offline  
Old August 31, 2014, 03:18 PM   #10
Crusty Deary Ol'Coot
Senior Member
 
Join Date: November 19, 2009
Location: Deary, Ideeeeeeho
Posts: 522
Bart B,

Looks like we need to agree to disagree here, but --------

If you will read my post carefully, you will see I address the fact that some say that rifles shoot better with some degree of stock to barrel pressure, and if that is fact on a given rifle, fine. But ----- what happens when there is a change in conditions, the stock swells or shrinks, the temp is 13 degrees rather then 74 as it was when the rifle was sighted in or the load developed.

The point I try to make is that for a hunting rifle, consistency trumps groups.

If I am shooting some type of bench rest competition, I'll likely be allowed sighters so that adjustment can be made for the point of impact to which my rifle is shooting at that time/place.

However, sighters are not allowed in a hunting situation, and as said, consistency of the expected point of impact is much more important then shaving a 1/4" off the group.

That quarter inch won't be a factor one way or the other in taking a game animal, but an unexpected shift in P.O.I. of quite possibiliy some inches, high. low, right, left or a combination of any two could very well make a difference, especially at extended ranges.

Plenty of room for those whose boat is floated by a tightly bedded barrel/stock or a stock which supplies some degree of upward pressure to their barrel. To each his own and what gives them confidence in their equipment.

But personally I'll be better served knowing that NO outside force will be able to adversely affect my expected point of impact even at the sacrifice of a slightly larger group size.

However, I have yet to be forced to make that sacrifice.

Crusty Deary Ol'Coot
Crusty Deary Ol'Coot is offline  
Old August 31, 2014, 04:07 PM   #11
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,038
Crusty, I was commenting on "this is a .22 rimfire being talked about here and as such there will be a minimum amount of reaction between the hard surface and the rifle when compared with a harder recoiling firearm." ... when I stated that others think otherwise. May not have appeard that way.

Those tuners on rimfire 22's cause much more than 1/4 inch errors at 100 yards. The best ammo at the time would easily shoot no worse than 1/2 inch at 100 yards and the 1/2 inch or more problems those Freeland style tuners caused was a lot more than that.

Yes, there are rifles that shoot better when hand held atop a bench with fore ends putting pressure on the barrel. Afield in unsupported shooting postions, the zeros change and accuracy degrades. That's what rimfire shooters found out with their systems as well as centerfire rifle competitors; if the shooter was good enough to tell the difference.

In some centerfire rifle matches, there are no sighters; every shot counts. I've never known a rifle match winner nor record setter whose bolt action rifle forend tip put pressure on the barrel. Service rifles used in competition, such as the M1 and M14 are norious for changing zeros when sling pressure changes the pressure the stock ferrule puts on the barrel's lower band. And the problems are closer to 1 MOA instead of 1/4 MOA.
__________________
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 offline  
Old August 31, 2014, 05:35 PM   #12
Crusty Deary Ol'Coot
Senior Member
 
Join Date: November 19, 2009
Location: Deary, Ideeeeeeho
Posts: 522
Bart,

Will sure need to defer to your expertise here, Have never used any tuning devices, in a any form.

Have a couple very fine shooting .22 rimfires, but for hunting am as stated very big on consistency and nothing messing with the expected Point of impact.

My 10/22 build is floated while the Clark Custom 77/22 is not.

The Clark just shoots so very well as it came from Clark, I have never taken it apart. It is not a game rifle so I don't worry about it, but were I to change stocks on that rifle, I'd at least try floating to see how the .920 Walther tube reacts.

I believe the advice given where you indicated the problems that come with resting a firearm solidly against a hard surface are very valid. But, I have not tested that issue to find just what may or may not occur and how much.

later,

CDOC
Crusty Deary Ol'Coot is offline  
Old September 4, 2014, 09:50 AM   #13
Unlicensed Dremel
Senior Member
 
Join Date: February 13, 2014
Posts: 1,656
Quote:
It's not harmonics, it's up pressure
Well, it's both - it's "up pressure" which affects the harmonics.

Yeah, that's pretty common. There's a supposedly famous "great white TV hunter" type guy (ya know, a "professional" hunter) with a youtube vid where it shows him shooting game resting his barrel on a tripod. A novice touted as an expert - too funny.
__________________
--Only accurate rifles are interesting, and only *really* accurate rifles are *really* interesting.
--Life is *way* too short to shoot or hunt with ugly plain plastic stocked guns.
Unlicensed Dremel is offline  
Old September 5, 2014, 01:57 PM   #14
4V50 Gary
Staff
 
Join Date: November 2, 1998
Location: Colorado
Posts: 16,943
At school a dial indicator was placed against a barrel. A pencil then pushed against the barrel with the resulting jump displayed by the indicator. Lesson: no pressure on barrel but if there is, make it consistent. You want consistent harmonics for consistent shot placement. Sometimes minute of mastadon is not good enough.
__________________
Vigilantibus et non dormientibus jura subveniunt. Molon Labe!
4V50 Gary is online now  
Old September 5, 2014, 04:36 PM   #15
Crusty Deary Ol'Coot
Senior Member
 
Join Date: November 19, 2009
Location: Deary, Ideeeeeeho
Posts: 522
Well saidGary!

CDOC
Crusty Deary Ol'Coot is offline  
Old September 10, 2014, 12:48 PM   #16
James K
Staff
 
Join Date: March 17, 1999
Posts: 19,682
The same problem can occur if a handgun butt or barrel is rested on a solid support; if using a rest the wrists should be on the rest with the hands and gun not touching the rest.

Jim
__________________
Jim K
James K is offline  
Old September 12, 2014, 10:30 AM   #17
Jim Watson
Senior Member
 
Join Date: October 25, 2001
Location: Alabama
Posts: 11,214
I would be more suspicious of the slip fit barrel with clamp on a 10-22 than I would the harmonics or the bedding or any of the stuff that is considered important on a bolt action.

Most of us BPCR shooters will rest our barrels in the buffalo sticks. We do make an effort to rest them at the same point, many are marked with tape at a sweet spot or just the same spot.
Jim Watson 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 10:13 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 0.10573 seconds with 9 queries