I need to re-cut a barrel - Toronto GTA or North of 407

bigHUN

bigHUN

CGN frequent flyer
Rating - 100%
3   0   0
Location
Aurora/ON
I got couple new barrels over a winter, but actually started shooting-testing this .22x500mm only last week.
I cannot make the grouping right. Tried with two different Brand and different weight pellets. Tried different speeds no bueno.
I just pushed some pellets through couple of barrels for comparison, inspected with a high power jewellery lupe lens, all looks good no signs what could be wrong.
And then I look into this problematic barrel hole with a lens, both ends. My Mr source was using a floating crowning tool.
Now I need a gunsmith or any lathe operator with barrel work experience who have done these things successfully.
Can you point me please?
I live in L4G7X4
 
sillymike said:
Cut and crown, or just the crown touched up?
Click to expand...

I only read it online that those concentric scratch marks possibly coming from a crowning tool and can effect the POI badly. I just assume the barrel shall be cut and re-crown but a more experienced gunner/machinist can advise otherwise...
Polishing a crown I shall be able diy with hand tools, I even have a arrow cutting jig and I can roll the barrel on bearings.
But I have no lathe to cut of some 5-10 mm from the front tip, if that would be the advise.
This is a 14mm OD x500 mm length poly barrel unchoked with 450mm twist rate, suitable for heavy pellets and slugs.
 
Not sure about your concentric scratch, but if it's crown that needs a clean up. You could make crown-lapping-tool with a brass screw.
- Then have at it with valve grinding compound.

Or buy one online

s-l400.jpg
 
bigHUN said:
I only read it online that those concentric scratch marks possibly coming from a crowning tool and can effect the POI badly. I just assume the barrel shall be cut and re-crown but a more experienced gunner/machinist can advise otherwise...
Polishing a crown I shall be able diy with hand tools, I even have a arrow cutting jig and I can roll the barrel on bearings.
But I have no lathe to cut of some 5-10 mm from the front tip, if that would be the advise.
This is a 14mm OD x500 mm length poly barrel unchoked with 450mm twist rate, suitable for heavy pellets and slugs.
Click to expand...

A couple of your points - above - "roll the barrel" - so that presumes that the bore within the barrel is perfectly concentric with the outside of the barrel - often it is not - is often the cause of off-set crowns - indicating on the outside of the barrel, and assuming that is concentric to the bore. I have and use a hand crowning tool from Brownells that uses a brass pilot into the barrel - steel pilot are also available or can be made - so those pilots ride on top face of the rifling - perhaps 3 cm or more long - is sometimes a fussy thing to make a pilot on my lathe that is a nice sliding, snug fit to that rifling diameter - but the cutting tool is indicating off the top faces of the rifling - not the outside of the barrel. A friend borrowed the tool - had a snug pilot made for his muzzle - I have same rifle - when I got it back, that pilot would not go into my muzzle - needed no more than a "polish" in lathe with some 320 grit emory - but that was enough to be the difference between it going into mine, versus not - my rifling diameter versus the rifling diameter in his barrel.

The last barrel that I did was a 9.3x57 barrel that was cut back to 20" length - I did not have a .36 whatever pilot, so started with one for a .375" barrel (from Brownells) - required multiple trips to lathe to get just enough for lubed, sliding slip fit into that bore - and muzzle "looks" fine - was 9 degree crown, and I finished with a very tiny touch with 45 degree cutter - just enough to break the edge of the grooves at the muzzle - that meant there is larger 45 degree faces on the four "riflings" - but makes a continuous sharp edge all around that muzzle to let go of that bullet, evenly.

Concentric scratch marks - maybe at very fussy levels of target shooting, it is possible that any marks on the face of crown might be significant - was a thing some time ago about a "target crown" to be cut at 9 degrees or something. Is actually the precise edge all the way around the bore and rifling that is of primary and first main concern, I think - so that the barrel lets go of the bullet - all the way around - at precisely the same time - does not "hang on" a few thousandths more on one side or other - more or less definition of "perfectly" right angle to the centre of the bore line, which since bores are not guaranteed to be centered within the barrel - can mean that the "perfect muzzle crowning" might not be centered on the barrel.
 
Last edited:
Potashminer said:
...a hand crowning tool from Brownells that uses a brass pilot into the barrel....snug fit to that rifling diameter...
Click to expand...

I think that tool shank you describing made the concentric scratch marks inside rifling. Or I was not careful enough and when polished the brand new barrels I let the rod exit at the muzzle....but a brass shall not scratch it inside that fast.
My tinkering is only based what I have seen pictures on internet and what people were saying about.
The re-crowning I am sure I can eventually DIY. This I will do first and I will test the POI again at least 50 meters. If the improvement is not enough I think it would be better just to chop of 1/2" from the barrel tip and start from scratch. This poly barrel suppose to be be my target match scorer.
I don't see where are you located, anywhere close to L4G7X4?
 
My "location" should be on my identification on this site - to left of text that I post - it should say that I am in Western Manitoba - I am sort of "in the bush", maybe 5 miles from Sask border - Postal Code for me is R0J 1W0 - is where we get our mail, not where we live, so likely a "far piece" between you and I!

I misunderstood your earlier post - I did not realize the concentric scratches were on the top faces of the rifling - I thought you were describing the face of the crown at end of the barrel ...

I suspect that you will discover that your "group size" will be a function of the load that you use, the rifle (bedding, trigger, barrel), and your shooting skill and techniques. I am not convinced that weakness in one area can be offset by strengths in the other areas. I do know that some experienced competitor people purchase like 3 barrels at a time, or three rifles - then shoot all three - pick the "best" one - the one that produces best groups - and sell the other two. Would think all are the same (barrels, rifles), but evidence is that they are not. I have at least once purchased the two "second best" barrels - I am not good enough shooter, rifle builder and hand loader to notice that they are not "the best" barrel.
 
Last edited:
Potashminer said:
My "location"
Click to expand...

The concentric marks are inside the barrel on top of the rifling, as much I can see inside with a lupe - maybe 5 or 10 mm long. This what concerns me the most, the crown itself I don't care much easy fix, I just picked up a full pocket of brass ballhead screws from HomeDepot, tomorrow is a day for this workparty :)
I don't use bipods but a levelling head tripod with a rear monopod vs rest bags, so the aiming errors are out of consideration. I can see in my scope (the larger and heavier pellets only) that they spiralling and kin d of feels like randomly spiralling with a random POI. Also over this winter I built my own one-piece-rest for 100 meters BR also EBR for longer distances (with rifle of course).
Yes I understand what you are saying, I was competing archery for almost two decades and we were doing the same with arrow shafts...to collect a best flying dozen arrow I needed to collect at least from 3 dozens...many times I've bought like ten dozen shafts and sold 8 of them.
 
I got my barrels muzzle squared on a lathe. The flat finish look clean.
What next?
To crown or leave it flat and square?
 
As I think I mentioned or alluded above - I am not a high end target rifle builder - so if that were me, is time to shoot those barrels - see if that made a difference or not. Internet posting suggest that flat and square should be very best shape for front end of barrel - was a thing where some thought a 9 degree taper was "better" - is holes on target that tell you?? I personally think is the last points of contact with bullet that "matter" - must be all the same - therefore must be right angle to centre line of the bore hole. Maybe that was your issue? Could be bedding?? Could be barrel quality?? Could be your skill or technique? I do not know how to tell, except deal with one item at a time - and see what difference that makes on target - even could be your loads?? I do not think there is a magic "Easy" button to solve any particular issue??
 
Potashminer said:
....if that were me, is time to shoot those barrels - see if that made a difference or not....
Click to expand...

Thanks. I visited today a gunsmith, an older very polite guy, he is building shotguns per order. He have no airgun experience but have seen barrels and barrels, and he actually proposed to leave the muzzle squared and test shot. I am hoping that I can well take care of it in safest way not banging it around. Waiting now for a weekend to test shot, 50-80 shots shall clean any micro burs if any left.
 
All the barrels Ive ever cut were flat and square any relief would be to protect the crown.
Once cut I would is a brass round head screw and valve lapping paste to remove the burrs.
I also check the end of the barrel inside diameter for oval with a bore gauge. I sometimes use a die and press to add a little choke which sometimes helps.
 
I just finished crowning tree out of four barrels with a brass screw.
Pushed some pellets through, and I had to re-do one crown the very first I did, I had maybe a way to high RPM and that pushed a material inside and developed a wire edge.
For now visually looks good, pellets doesn't clipping, I am so excited to see how the lead flies. Tomorrow is a range day.
 
Good Luck!

I was doing a bit of reading on-line, and then reviewed your posts above. You might want to research "artillery hold" - that technique might help improve your groups? As I follow, it seems that the pellet in a springer air rifle does not move until the piston stops. So that rifle is already moving in recoil, before the pellet starts to move. And with relatively slow barrel time, what can happen between breaking the sear and the pellet exiting is significant. Apparently is not the same as with a powder burning rifle - in those, the bullet starts to move from the same event that is starts the rifle recoil movement. You mentioned the apparatus that you use for aiming, but I missed any discussion about what is needed or is done about follow-through.

I was sort of surprised - as if the role of the shooter / grip / follow through is more significant with air rifles - or at least more exaggerated - than it can be for powder burning shooters.
 
You must log in or register to reply here.
Back
Top Bottom