Accuracy from a shortened barrel - what to expect?

[elkeater2]

I've got a TC Encore barrel - 28" 25-06. Well, it was, I shortened it to 24". Partly because it was unhandy to carry, maneuver in and out of cases and vehicles. Partly because I read too much and it seemed like the consensus was shorter was better. I wanted to see if I could do it myself and make it look decent, and hoped it would be maybe a little more accurate, although it had been acceptable always. Barrel picture shows it before final polishing. Re-crowned - or crowned actually the first time because it had none!

In the course of my reading and load development I have identified nodes and done ladder tests, etc.
My real question is this: should I expect close to the same results with my previous loads? I'm thinking the harmonics should be similar but less. Haven't had a chance to shoot much. One load still shot into less than an inch on a windy day, and the velocity for that load was down only about 60 fps. The only one I tested so far. So just curious what others have experienced after shortening a barrel significantly. EE2

 

[cloverleaf]

Looks much better than my effort to recrown a barrel. Turned an old 22 into a tomato stake. :lol: CL

 

[Thebear_78]

Looks much better than my effort to recrown a barrel. Turned an old 22 into a tomato stake. :lol: CL

What did you use to crown it? I have crowned many on a lathe.


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[elkeater2]

I posted here in Reloading because I'm hoping my inventory of loaded rounds and with different bullet weights will all work OK. The actual shortening and crowning was easy enough I'll likely post pictures over in Rifles later today. Hacksaw with new bi-metal 18 tpi blade. I have a spare heavy vise I clamped to a Workmate, then put an angle grinder with flat flapper disc in the vise vertically. Made a v-shaped jig out of a couple pieces of wood. Aligned it all so the barrel was pretty square to the grinder and clamped everything down. Grinder on, just laid the barrel in the V and held it down while turning slowly and just easing it up to the grinder. Never let it get too hot to the touch. Then moved the jig to position for the outside chamfer and did the same. Redneck? Oh yeah, but it worked. Crowned with a brass ball floor lamp top, valve grinding compound and cordless drill.

 

[1Shot]

I have re-crowned a number of barrels with round head brass bolt chucked in a variable speed drill using valve grinding compound. Just go slow and check results often. Works like a charm. As to the OP questions. You will never know the results until you get to shooting. Glad that you left the barrel at least 24". 25-06 in my experience needs at least 24" barrel. I prefer 26" myself. Usually if the barrel is of good quality it does not matter the length as far as accuracy goes. Harmonics do effect things and the Encore it's self is a different critter to deal with compared to a bolt action. Let us know your results.

 

[Songdog]

I’ve hacksawed several barrels. The last one, was a 7 Mag that went from 26” to 23”. The exact same loads lost about 50 FPS... and shot better than before.

In fact...... of the half-dozen rifles I’ve chopped and recrowned.... I can’t think of one where the accuracy suffered, even with the same loads, and a couple got noticeably better.

I’m not sold on “harmonics” having as great an effect on accuracy “nodes” as most people.... I theorize that the “Node” is more a function of muzzle crown, high-pressure gas escaping the bore, and base of the bullet all jiving, than it is catching the peak or valley of a steel tube oscillating at 30,000 Hz.... Call it “Optimal Bore Exit” conditions.

A simple change of the crown from 9* to 13* does NOTHING to change the “harmonics” of the barrel... but can heavily effect the “accuracy” of the very same load. This is exacerbated by the addition of a boat-tail to the base of the bullet.... for obvious Hose-nozzle reasons.

 

[Whitesheep]

A few years ago, not satisfied with the accuracy of a T/C Prohunter in .280 Rem, I had Mike Bellem cut 5" off the barrel and recrown. The accuracy improvement with the now 23" barrel was amazing. The velocity loss was 105 fps. I am happy to trade the velocity for a now sub MOA rifle that was a 2 MOA before.

If you are at T/C owner you should check out his offerings as well as that of Match Grade Machine. These are the goto guys of the T/C world in my humble opinion.
https://www.bellmtcs.com/bellm
https://matchgrademachine.com/

 

[5shot]

when you shorten a barrel, you make it stiffer, so in theory, it should be more accurate. If you get a good square crown, I can't imagine it grouping worse.

 

[gbflyer]

Those Encores make a nice compact package. I have a 18” .223 and a 16.25” 300 BLK. Both have acceptable accuracy and are great with suppressors. The .300 is almost Hollywood quiet with subsonics.

 

[elkeater2]

I’ve hacksawed several barrels. The last one, was a 7 Mag that went from 26” to 23”. The exact same loads lost about 50 FPS... and shot better than before.

In fact...... of the half-dozen rifles I’ve chopped and recrowned.... I can’t think of one where the accuracy suffered, even with the same loads, and a couple got noticeably better.

I’m not sold on “harmonics” having as great an effect on accuracy “nodes” as most people.... I theorize that the “Node” is more a function of muzzle crown, high-pressure gas escaping the bore, and base of the bullet all jiving, than it is catching the peak or valley of a steel tube oscillating at 30,000 Hz.... Call it “Optimal Bore Exit” conditions.

A simple change of the crown from 9* to 13* does NOTHING to change the “harmonics” of the barrel... but can heavily effect the “accuracy” of the very same load. This is exacerbated by the addition of a boat-tail to the base of the bullet.... for obvious Hose-nozzle reasons.

Songdog, thanks! I've been wondering about degree angles and flat base vs boattail comparisons, but haven't found much info. Do you have a source? I've also encountered online confusion about what exactly is the crown vs. the muzzle face and muzzle contour. To me, the crown - if there is one - is the very slight taper introduced at the very edge of the lands and grooves by machining or brass/grinding compound. I also need to be sure when we talk degrees of crown that we are measuring from the vertical face of the muzzle. That makes sense when talking 11*, 9*, 13*. When people say 45* I guess it doesn't matter! I have a lot of Ballistic Tips with the slight boattail. Also a number of flat bases like PT's. Do you have a degree recommendation for them? Thanks again. EE2

 

[cloverleaf]

Looks much better than my effort to recrown a barrel. Turned an old 22 into a tomato stake. :lol: CL

What did you use to crown it? I have crowned many on a lathe.


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Ashamed to admit it....hack saw and a file...many years ago. Obviously didnt know what I was doing... could do better now.... CL

 

[elkeater2]

This is the arrangement I used. The wood jig is positioned for the chamfer on the outside corner of the muzzle in this pic. I squared it up to the grinder wheel for the end surfacing. It ain't no lathe, but with patience and lots of measuring it worked. Crown was brass ball/valve grinding paste and cordless drill. Polished with 600 wet or dry.

 

[cloverleaf]

Yup- that looks like a good plan. Lotsa respect for the guys that know how to a mill and lathe etc. but more for the guys who "engineer" a way to get it done, and done well. The "internet wisdom" that I recite is a shorter barrel should be more accurate, given the harmonics of a shorter "whip" are "Smaller" oscilations. Assuming all else being equal, which it never is. That's the only thing I know for sure...everything else is never equal. Obviously the crown needs to be even and smooth with rifling ending evenly. Looks like you got that! CL

 

[gbflyer]

I’ve read a couple of articles written about crown voodoo. The take away for me was that even one cut with a metal chop saw worked nearly as well as a machined crown after the first couple of shots. There was some POI change but group size was not effected all that much in terms of practicality. I used to agonize over it the first few barrel jobs I did. It’s really not a huge deal.

Good job. Many ways to skin a cat.