KEEP ME IN TUNE

Get or give advice on equipment, reloading and other technical issues.

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John T
Posts: 152
Joined: Sat Jan 07, 2006 5:42 pm
Location: Brisbane

KEEP ME IN TUNE

#1 Postby John T » Thu May 10, 2018 8:01 pm

Hello.

Why does my rifle slip in performance?

If you have been lucky enough to have your rifle hit where you point it, what do you do when that stops?

Stop jamming.

There will be plenty to say. About 99% would like an answer.

Regards,
John Tracey.
10.5.18

GSells
Posts: 335
Joined: Sun Aug 13, 2017 11:04 pm

Re: KEEP ME IN TUNE

#2 Postby GSells » Thu May 10, 2018 9:17 pm

So many answers to a simple question !
Carbon ? Harmonics? Throat erosion ? Barrel ware ?Degrading optimum charge weight? Just a few things !

bruce moulds
Posts: 2368
Joined: Sun Jun 19, 2005 4:07 pm

Re: KEEP ME IN TUNE

#3 Postby bruce moulds » Thu May 10, 2018 10:07 pm

powder charge, bullet relation to rifling, good places to start.
barrel clean and not shot out.
crowning.
tuner adjustment.
"SUCH IS LIFE" Edward Kelly 11 nov 1880
http://youtu.be/YRaRCCZjdTM

Tim N
Posts: 885
Joined: Fri Jan 25, 2013 8:18 pm
Location: Branxton NSW

Re: KEEP ME IN TUNE

#4 Postby Tim N » Fri May 11, 2018 8:01 am

Cleanliness is next to Godliness.
Find someone with a borescope who knows what they are looking at to tell you the condition of your barrel, the patches can lie.
Barrels - like tyres are a consumable.
We don't rise to the level of our expectations, we fall to the level of our training. Archilochos 680-645 BC

Brad Y
Posts: 2012
Joined: Fri Jun 26, 2009 8:21 pm

Re: KEEP ME IN TUNE

#5 Postby Brad Y » Fri May 11, 2018 8:37 am

One thing I noticed is a fair bit of arrogance in this regard. People have rifles that are very accurate. But then they foul and can’t smash the center. First thing they blame is the ET they shoot on. Then claim conditions are bad when others are putting in high scores. As Tim said, barrel cleaning is paramount. Don’t know how many times I’ve revived a club members rifle with a bit of jb paste. I do think that people should have to get a license to use a borescope though. Seems like it makes you an instant expert in everything barrels if you own one.

Gyro
Posts: 349
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: KEEP ME IN TUNE

#6 Postby Gyro » Fri May 11, 2018 8:43 am

I don't have a bore scope so I reason to err on the side of over cleaning just to hopefully be sure of staying ahead of the build up. Plus I make damn sure to get somebody with a bore scope to have an occasional look inside just to monitor the cleaning regime I'm using. Without a bore scope I'm just guessing tho.

One day I'll get a bore scope just like one day I'll get my dream scope ! Money !

The problem with "over cleaning " is the settle down period that may be required before the gun shoots well again ?
Last edited by Gyro on Fri May 11, 2018 4:11 pm, edited 1 time in total.

Wal86
Posts: 150
Joined: Sun Nov 20, 2016 5:10 pm
Location: Kilmore, VIC

Re: KEEP ME IN TUNE

#7 Postby Wal86 » Fri May 11, 2018 10:01 am

Gyro wrote:I don't have a bore scope so I reason to err on the side of over cleaning just to hopefully be sure stay of staying ahead of the build up. Plus I make damn sure to get somebody with a bore scope to have an occasional look inside just to monitor the cleaning regime I'm using. Without a bore scope I'm just guessing tho.

One day I'll get a bore scope just like one day I'll get my dream scope ! Money !

The problem with "over cleaning " is the settle down period that may be required before the gun shoots well again ?



I don't believe you can over clean a barrel at all... If you do due diligence in barrel cleaning and conditioning of barrel your first shot will go in 100%.. Another reason why I dont think much about ES as being that important to load tune as first shot clean barrel velocities generally differ..

Tim is right that cleanliness is godliness...
No point measuring your projectiles OD if you dont control what your driving them down..
Just a thought

cheers

John T
Posts: 152
Joined: Sat Jan 07, 2006 5:42 pm
Location: Brisbane

Re: KEEP ME IN TUNE

#8 Postby John T » Mon May 14, 2018 7:08 pm

Hello all.

Assume that you have developed a "load" ( best-tested combination of brass, sizing, neck tension, primer, powder and load, seating etc.) for your bullet-of-choice that is "in tune" with your rifle to the extent that you have confidence in maintaining X-Ring (.5moa) elevation at 1000 yards. (Please, try not to divert this topic into "Load Development". That can be the "Subject for the Ages" at another time.)

Accepting the common theory(s) of the wave pattern(s) of a barrel under recoil, your bullets are all exiting the muzzle on the upstroke of a vibrating barrel wave, between the node and the top antinode. If this exit band (EB) 'moves" and/or increases, there will be a decline in the consistency of bullet flight and therefore of accuracy. Your string increases beyond the X. (For these purposes, only the vertical plane is considered.)

Why? A change in chamber pressure (CP) and/or increased variation of CP; because MV and bullet exit angle are inexorably tied to CP.

Amongst a number of causes, the most popular is powder variation, batch to batch. The very best shooters are likely test each new batch. At my stage, and volume of use, I do not bother.

If powder has been eliminated and all else is the same, why has accuracy/CP declined?

As Barry (and others who once kindly contributed) has said, ultimately, the correct tune is the best combination of powder weight and seating depth for that rifle and bullet.

It is a fact that when the bullet is jammed into the rifling, there is an increase in the spike of initial CP, caused by the increased initial resistance. What happens if that resistance goes down? The CP goes down and so does the MV. So what, I'll just come up a quarter. Not so simple.

Your EB has moved up. If its upper (slower) edge has moved past the top (antinode) of the wave, the slowest shots will be low, 5 if you're lucky.

Why would the resistance go down? Throat erosion.

OK. I'll push the bullet forward. Again, not so simple.

Dinner calls. More later, maybe.

Regards,
John Tracey.
14.5.18

wsftr
Posts: 52
Joined: Tue Jan 30, 2018 12:58 pm

Re: KEEP ME IN TUNE

#9 Postby wsftr » Sat Jun 02, 2018 1:58 pm

Wal86 wrote:
Gyro wrote:I don't have a bore scope so I reason to err on the side of over cleaning just to hopefully be sure stay of staying ahead of the build up. Plus I make damn sure to get somebody with a bore scope to have an occasional look inside just to monitor the cleaning regime I'm using. Without a bore scope I'm just guessing tho.

One day I'll get a bore scope just like one day I'll get my dream scope ! Money !

The problem with "over cleaning " is the settle down period that may be required before the gun shoots well again ?



I don't believe you can over clean a barrel at all... If you do due diligence in barrel cleaning and conditioning of barrel your first shot will go in 100%.. Another reason why I dont think much about ES as being that important to load tune as first shot clean barrel velocities generally differ..

Tim is right that cleanliness is godliness...
No point measuring your projectiles OD if you dont control what your driving them down..
Just a thought

cheers


What does that equate to? Are you talking of some barrel break in regime or something post the clean of the rifle?

Wal86
Posts: 150
Joined: Sun Nov 20, 2016 5:10 pm
Location: Kilmore, VIC

Re: KEEP ME IN TUNE

#10 Postby Wal86 » Sat Jun 02, 2018 2:48 pm

wsftr,

Basically you can never over clean a barrel in my opinion, if you condition your barrel before firing that first shot..
By conditioning i mean creating an environment in your clean barrel that replicates a barrel that's settled.. (Settled doesn't mean "dirty" your barrel has now actually self lubricated..)
Think about what happens to a bullet when fired down a clean dry barrel, and the condition that leaves your barrel in after it leaves...
Another thing that will help, is reduce the variables and do your load development on a clean barrel..
A good way of trailing different conditioning methods is during the breaking in process clean/shoot...
Hope this helps

Cheers

wsftr
Posts: 52
Joined: Tue Jan 30, 2018 12:58 pm

Re: KEEP ME IN TUNE

#11 Postby wsftr » Sat Jun 02, 2018 3:30 pm

Thanks for the response :)


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