If I cut 6" from a GM barrel-Effect on accuracy?

[Davemuzz]

My GM Barrel, 50 cal, 1-70 twist is very accurate. And I would really hate to do anything to screw up that accuracy”¦..but I'd like to lose some of that weight.

So, I'm just tossing out the thought of "what if" I cut off 6" of the barrel? I'm certian it will make the rifle lighter, and I will think it may lose some velocity, but I don't want to lose the accuracy of this barrel.

Just asking if anyone else has done a barrel chop and had regrets? If so, maybe I should consider just buying a shorter barrel.

Thanks

Dave

 

[BrownBear]

With a good recrown, I've never seen a barrel lose accuracy from cropping. Theorists and typists might pose different thoughts, but my guns speak for themselves.

 

[roundball]

Theorists and typists might pose different thoughts

You nailed it...no shortage of that, LOL

 

[jamesthomas]

How long is the Barrel? Somebody did a test for this and found out that you lost 10ft per second for every inch you cut off. A 42" to a 38" is not to bad, But if its a full stock you'll have to think about redoing the forestock and cutting a new front sight, plus changing ramrod thimbles an pins.

 

[Ed Wingenroth]

Hi All !!!

The story goes that a properly rifled bore is tighter toward the muzzle than the rest of the bore !!! You may want to talk to some Barrel maker's to confirm this ..... If true you might have to shorten the Breach end and save some of that work mentioned before.....

Ed....

 

[necchi]

Sage advice Red-Wing,
But I'm pretty sure that is not the case with the GM barrels, they're pretty much mass produced button cut barrels with a concentric bore end to end.

 

[frogwalking]

Track of the Wolf strongly reccomends that if you shorten a barrel that you cut off the breech and reinstall the breechplug rather than cut off the muzzle end. I know this because I had them shorten a GM barrel from 42 inches to 38 in order to build a lighter rifle. (I don't know if they are theorists or typists.) They explained their reasoning, but I don't remember what it was.

 

[galamb]

Tracks theory is that the crown as it comes from the barrel maker (Rice, GM, Colerain) is better than they can put back if they shorten the muzzle end so would rather shorten the breech end and re-cut the threads there.

That is very doable with a straight barrel but with a taper or a swamp you may not want to cut the breech end depending on the profile you want to keep.

As to the effect of a shortened barrel.

Here's a chart from Rice. They started with a long barrel and cut it back a couple of inches and tested again - make what you will from the results.

(one note - it appears that the 34" and 36" results were transposed but I did not confirm that with Jason at Rice).

Sorry, had to scale back the chart to get it all in - try zooming your screen, the quality is decent when it's blown up.

(or here's a link to the page Link to Rice test )

 

[MSW]

from what I've read, the GM barrels are concentric and do not change dimension at the muzzle. assuming a good crown, I suspect all you'll lose will be a bit of sight radius, and some weight...

good luck with your project, and let us know how it turns out.

make good smoke!

 

[Birddog6]

Personally, I don't think the Barrel will be any less accurate. :hmm:

However, taking 6" off the muzzle Could very well change the velocity some & that could change the Special Load you have worked up for that barrel. Thus you may have to refine the load again to get it back to where it was.

Then again, it may improve the load ? No way of really knowing til ya try it.

Keith Lisle

 

[galamb]

If anything would "appear" to reduce the accuracy I would suggest it would be the shorter sight radius.

Whether the barrel is 20, 30 or 40 inches probably does next to nothing to change the "barrels accuracy".

But I will say I am a far better shot with my 42" barrel than my 28" - simply because of the longer sight radius any minor twitch/movement has a much smaller effect on the impact point compared with the shorter radius on the shorter barrel. (think rifle vs pistol at 50 or 75 yards - as an extreme comparison)

If you are shooting "off hand" I suspect any "perceived inaccuracy", in comparison, would be far more "obvious" than if you are shooting off a rest. Unfortunately, once you have cut the barrel if you find you can't shoot it worth a darn, you can't put the metal back.

 

[dbutch]

Just bore large holes under the butt plate and add all the weight you can..
You will be suprised when you move the balance point back 4" how the rifle feels and balances between your hands..
try that before cutting your good shooting bbl.
Good luck, plz report back on out come...

 

[Davemuzz]

Well, right now I do have that worthless patch box that's been there for 30 years. :haha: Maybe a good filling with lead will change my mind about front heavy”¦.and that patch box that I've always kind of disliked.

Dave

 

[Blackbruin]

I have a 15/16 27" green mountain 1-70 .54 southern poor boy, shoots just fine if i do my part

 

[galamb]

Dave, what is the length of the barrel now, and what is it across the flats?

I have a 7/8" atf, 36", 50 cal GM barrel on a fullstock and it holds pretty well - plus it's fully a pound and half lighter than even my 12 gauge (although more muzzle heavy).

If you go "too light" out front you may find that it wanders too much for your liking.

Given that, I certainly would try the suggestion of adding weight in the butt end. If you don't like it you still could cut her back a bit, no harm done.

I had a 10 1/2 pound rifle that "balanced well" and you didn't notice the weight when holding it on target or bambi - it just was a bit much to carry when threading your way through dense hardwoods.

 

[ohio ramrod]

another recommendation for counter balancing the barrel with lead under the buttplate. I do this with all youth guns to help balance the gun. :idunno:

 

[Davemuzz]

It's a 15\16ths flats and I just measured it at 33" long. Now, the rifle was hanging above the fireplace and I didn't take it down”¦so I could be off an inch or so on the length, but it's a T\C GM replacement so I know the flats are measured right.

Dave

 

[galamb]

Ok, so with a 15/16" barrel you have about 2 1/3 oz per inch.

Taking her back to 28" would save you roughly half a pound out front.

Would also have to trim back the rib and move the forward most ramrod pipe, cut a new dovetail to move the sight.

You would lose some velocity (with the same load you used before) which could be recovered by increasing the charge - assuming your grouping won't spread out (at least it's "fun time" on the range working it back up again).

Going down to a 24'ish inch barrel would save you a pound, but you would amplify the issues of load, sight radius etc - and still only save "1 pound".

Not sure I would go through the retrofit unless also having the short barrel would be of significant benefit (shooting from a compact tree stand etc).

 

[jerrywh]

I have shortened a lot of barrels and done a lot of barrel work including making barrels and if you crown them correctly afterwards they will not loose any accuracy. Why should they? A lathe is mandatory in my opinion. Do not cut the breech end it is more of a pain than the muzzle.

 

[Davemuzz]

Well fellows, this post actually came out pretty well. I just received a PM from a member and agreed to buy (a deal I couldn't pass up) a barrel that will fit (drop in) that will need a little work”¦..but nothing I can't handle, that I can cut down and "make 'er fit" without messing with my current GM barrel.

I'll take pic's as I go and let you know "the project" from start to end.

Dave