Can a barrel chop affect the accuracy of a gun?

[malkiserow]

Can the accuracy of a rifle be affected by chopping and a re-crown?

 

And if it can, does this mean a new load might have to be worked up to get it sweet again?

 

Interested to know what experience is about on this

Edited August 19, 2015 by malkiserow

[Les*1066]

It will definitely be affected if the job isn't done correctly, yes. It is best done on a lathe - a hacksaw across your knee probably isn't the best approach! The crown is usually cut at around the 11 degree mark.

 

Even when done correctly, you will probably need to tweek the loads to compensate for the shorter barrel. Just how much you'll need to compensate will be a suck it and see operation.

[welshwarrior]

The work of done correctly often improves accuracy over a factory job. Traditional crown is 45* and radiused but 11* target crowns or anything in between work well.

 

Don't leave it to chance take it to a gun smith

Meant to add the load may or may not need a tweak.

[malkiserow]

Yes, a gunsmith. I'd not do it.

[Underdog]

One thing I would like to know is, when a muzzle is machined on a lathe, does one work the tooling out from centre instead of normal?

[welshwarrior]

Yes the crown is cut at the very end and it's cut outwards as opposed to inwards.

[malkiserow]

One thing I would like to know is, when a muzzle is machined on a lathe, does one work the tooling out from centre instead of normal?

 

I bet the answer is "it depends", I'd want mine centered on the bore which means working out

Yes the crown is cut at the very end and it's cut outwards as opposed to inwards.

 

I am sure you know better than me but Isn't the live centre in the bore?

Edited August 19, 2015 by malkiserow

[welshwarrior]

Not when you crowning it it's not also depends how you work some work between centres others off steadies but everything is worked concentric to the bore or at right angles for the shoulder etc.

[Underdog]

Yes the crown is cut at the very end and it's cut outwards as opposed to inwards.

Cheers, my common sense is still active :-)

[Old farrier]

Hi

So curiously on a 1 in 18 twist on a barrel I assume the crown is cut so the riffling allows the bullet to leave the barrel top dead centre so if you take 4 inches off the twist would be reduced by on 8th and as I see it the exit from the rifeling would possibly be at the side of top dead centre

Just a thought

Maybe there's a equation for how much to take of a barrel depending on twist ratio ?

Only a thought

All the best

Of

[malkiserow]

Interesting idea OF

 

I am thinking 23 inch to 21 inch on a 1in 9

[Old farrier]

Interesting idea OF

 

I am thinking 23 inch to 21 inch on a 1in 9

Used to do a lot of small bore target shooting

Lot of us had spirit level bubbles on the barrels to prevent cant on the gun as the trajectory of the bullet could put you off the bull so I assumed the bullet left the barrel top dead centre

Just a thought

Of

[Underdog]

You have me really confused now OF :-/

[Old farrier]

You have me really confused now OF :-/

Sorry about that UD

Think of a thread on a nut and bolt the bolt all ways starts at the same point and exits at the same point the thread (rifeling ) ensures this

so maybe a bullet does the same

The other variable to my (stupid ) thought is multi start rifeling

Just a thought 😋

All the best

Of

[Underdog]

Mate any canting issues is the relationship between the sighting plane and bore plane deviating from true vertical.

There is no need for the rifling to correspond at the muzzle with any vertical or horizontal plane. Its function is purely to rotate the bullet to a rate that offers stabilisation.

There is no need for any indexing of a bullet or cartridge.

 

Lol, your starting to remind me of me, over thinking! ;-)

[Dunkield]

Reducing the length of a centrefire will reduce the velocity of the round, the jury is out on whether the same happens with a rimfire.

Look up the shortening of the .223 barrel, it is one of the comprehensive tests I have seen, it think it comes from the Accurate Reloading site

 

Edit: here: http://www.accuratereloading.com/223sb.html

[Old farrier]

Mate any canting issues is the relationship between the sighting plane and bore plane deviating from true vertical.

There is no need for the rifling to correspond at the muzzle with any vertical or horizontal plane. Its function is purely to rotate the bullet to a rate that offers stabilisation.

There is no need for any indexing of a bullet or cartridge.

 

Lol, your starting to remind me of me, over thinking! ;-)

Yes I know but it's been fun 😋

Any chance your my brother 😋😋😋

All the best

Of

So will shortening affect the vibration of the barrel to the good or bad 😗

No I'd better stop

Sorry op

Couldn't resist 😂😂😂

[kent]

Done well it will make it shoot better or equal to previous

Crown improvements and or reducing barrel whip are the factors

You can't legal shorten a. 22 lr enough to significantly reduce its velocity

Shortening others depends on the cartridge in question. 243 ack needs a long barrel for max speed while. 22 hornet can get to pistol lengths without the velocity exactly dropping off a cliff

[malkiserow]

OK, plunge taken on a gun that was always very accurate, had the chop and it still shoots ok

 

The lower shot was the first one of the 4

 

It's a 275 Rigby at 100M, shooting prone off a bipod

[Underdog]

You mean a 7mm Mauser! ;-) Great round and looks like yours is still perfect :-)

[malkiserow]

Ja ja, das ist gutte, danke

[activeviii]

Bit late but yes, shortening the barrel can. Ause problems. Harmonics of the barrel and powder being the main. Cut to short and you can still have powder being spat out the end that's unburnt.

Is your putting a mod or a muzzle brake on then as long as the crown has no burr then angle makes little to no odds, you can cut it square for all is matters as the blast is different in a mod compared to uncut barrel.

 

I know of a 223AI 32" barrel. Build as a long range rifle. Would not group for love or money. Different mods, different ammo, powder, primers, crowning. Mother better than 1" at 200. In the end it had 2" cut off, same mod went on, it shot like a dream after that. As Kent said, whip of the barrel was the issue.

[Underdog]

Ja ja, das ist gutte, danke

Bitte.

[malkiserow]

Bit late but yes, shortening the barrel can. Ause problems. Harmonics of the barrel and powder being the main. Cut to short and you can still have powder being spat out the end that's unburnt.

Is your putting a mod or a muzzle brake on then as long as the crown has no burr then angle makes little to no odds, you can cut it square for all is matters as the blast is different in a mod compared to uncut barrel.

I know of a 223AI 32" barrel. Build as a long range rifle. Would not group for love or money. Different mods, different ammo, powder, primers, crowning. Mother better than 1" at 200. In the end it had 2" cut off, same mod went on, it shot like a dream after that. As Kent said, whip of the barrel was the issue.

I was worried about messing up a good gun but as lots said here ........ Not a problem and it is back to how it was before, just a little shorter and a mod can now go on. I am very happy.

 

activiii, the owner of that must have been pulling his hair out. ..... Glad it got sorted in the end.

[Dead-Eyed Duck]

Many moons ago I bought a Rem 700 in 22-50 Varmint heavy barrel.

 

As I intended sticking a long moderator on the end I asked the dealer to 'lop off' 4" from the barrel to make it more handy. He was horrified, but I insisted.

 

According to the literature that I read at the time this would lose 50fps for each 1" removed, and I was quite happy with that.

 

The end result was a very accurate rifle (I still have some targets that I shot with it) and I wish that I had never sold it.....

 

The trigger was poor by Sako/Tikka standards, but I shot loads of long range foxes with it.