Author Topic: Bad Crown on a Choked Barrel - Ideas? (Read 10713 times))

TooJung2Die · « **Reply #20 on:** November 11, 2014, 09:43:27 PM »

John - Thanks for the encouragement. Maybe a Chinese barrel will fit without too much machine work. I don't have access to a lathe. I've pulled out and re-installed barrels on break barrel springers. I can see that this barrel is press fit with splines on the barrel, no epoxy is evident.

K.O. · « **Reply #21 on:** November 12, 2014, 04:04:48 AM »

Hey Jon I held off just like cutting the barrel is a last resort the pre last resort to that is... (cause if you over do it can ruin the barrel?)

to try fire lapping once you feel you have no other option...

I did a mild fire lap on my 1377 with about 20 rounds and auto rubbing compound because of a groove that ran lengthwise down the barrel and it did the job I think there was just a very slight high spot because of it... it did not polish it all the way out but it didtake down the very slight ridge it caused.

I used a paper q tip and cut the tip off coated it with compound and put it directly in the barrel just past the beginning of the rifling using another qtip which I then used the other end of to clean the area behind the qtip in the barrel. the I loaded a 10.3 ultra mag and fired then 4 more pellets and then more compound and 4-5 more pellets then cleaned the barrel. it did polish the barrel and the scratch/groove while still there was lessened. I did another ten rounds and cleaned again and cleaned again the scratch was almost gone... I have put about a 500 tin thru since and can not see where it was... it did reduce 20 yard groups to about .5 from about .75 side rested...

Now what I did is not the usual use, it is supposed to help barrels like yours by taking down the high spots...

I fire lapped my long .22 barrels to polish them and it worked I used toothpaste for compound and about ten pellets same qtip method...
I know it did not hurt them...

So if you feel you have nothing to lose...

https://www.google.com/search?sourceid=navclient&aq=&oq=fire+lapping+an&ie=UTF-8&rlz=1T4ADFA_enUS508US508&q=fire+lapping+an+air+rifle&gs_l=hp..0.0i22i30l5.0.0.0.8225...........0.YN0SpWGKRTQ

TooJung2Die · « **Reply #22 on:** November 12, 2014, 11:44:07 AM »

It certainly won't hurt to try fire lapping first. I like the idea of using a q-tip to carry the abrasive ahead of the pellet. This barrel may call for more drastic measures. I think that if I were to remove the defects I'll end up with a barrel that is too loose. The defects I can feel are not subtle. I wish I was beginning with a barrel that shot .75" groups. It's closer to 2" at 25 yards. It's a 1992 and who knows how the previous owners treated it.

wilsonj1018 · « **Reply #23 on:** November 12, 2014, 11:47:25 AM »

did u ever try jsb 10.3?
Josh

TooJung2Die · « **Reply #24 on:** November 12, 2014, 12:05:38 PM »

Quote from: wilsonj1018 on November 12, 2014, 11:47:25 AM

did u ever try jsb 10.3?

I admit that I haven't. I have a pretty extensive pellet collection though and have always been able to get acceptable results with at least a couple of pellets I have on hand. Those are about the best groups I can achieve with CP 10.5. RWS pellets shoot about as well as my smooth bore Crosman 760 does with BBs.

wilsonj1018 · « **Reply #25 on:** November 12, 2014, 12:08:33 PM »

before going any further I would really suggest you try them. if I had any left id send you some but ive done away with .177.
Josh

mobilehomer · « **Reply #26 on:** November 12, 2014, 12:32:26 PM »

If you really want to do the crown, you don't need to cut any length. Carefully and slowly file the muzzle 'til you get past where the bore meets the muzzle. Then do the old brass screw trick to clean the edge.

K.O. · « **Reply #27 on:** November 12, 2014, 01:05:56 PM »

Quote from: wilsonj1018 on November 12, 2014, 12:08:33 PM

before going any further I would really suggest you try them. if I had any left id send you some but ive done away with .177.
Josh

Josh different pellets will not help a barrel that has problems...

"
The problem is very evident when pushing a pellet through from the breech. It's snug, then loose, then a couple more snug spots, then it feels like the ridges of a washboard for the last half barrel to the choke. There is another slight loose spot just before the choke. Those grooves are not just at the crown. You can feel them for half the length of the barrel.
"

wilsonj1018 · « **Reply #28 on:** November 12, 2014, 01:23:26 PM »

really? I obviously know nothing about barrels and airguns.

please show me more of the quotes I have already read wise one.... but its worth a shot before going to extreme measures.
Josh

K.O. · « **Reply #29 on:** November 12, 2014, 01:47:18 PM »

Quote from: wilsonj1018 on November 12, 2014, 01:23:26 PM

really? I obviously know nothing about barrels and airguns. please show me more of the quotes I have already read wise one.... but its worth a shot before going to extreme measures.
Josh

I guess maybe not as much as you think, I know I first started shooting over 40 years ago and am still willing to listen...

I would take the time to explain why that description I quoted tells that different pellets will not fix the problem but I obvious ruffled your feathers...

If you are willing please let me know how the JSBs will help... I just might learn something new...

wilsonj1018 · « **Reply #30 on:** November 12, 2014, 02:03:29 PM »

fair enough, back when I dabbled in airguns that typically came from the factory with "remarkable" barrels. I experimented and tried many things and many pellets. one bore was quite oversized and many pellets would fall into it a ways, one was tight at the muzzle end, another which ended up living on the rifle that I bought 4 barrels for had this issue of tight and loose spots in the bore. it shot nothing worth mentioning really. after various efforts of lapping back to health and yes lead slug in a .177 barrel is quite possible just a pita. well one last try was about all it took to push me over the edge. was ready to just have a lw machined to fit when someone suggested I try a jsb 10.3. never thought anything of it being more cylindrically shaped or longer than most other .177 nor did I think it would make any difference as I had various 10+gr pellets around. well I ordered some for @^52 and giggles. come to find out the gun ended up shooting 1/2-3/4in 5 shot groups at 50yds. maybe it was luck, maybe was the odd design of the pellet. so there is my reasoning. anything is worth a try and I had much rather buy a $14 tin of pellets and have a chance they may shoot well enough than to invest more time and money in a gun that's worth $250 at best.
Josh

TooJung2Die · « **Reply #31 on:** November 12, 2014, 03:26:36 PM »

I had doubts if fire-lapping would help but I liked Kirby's idea of loading the abrasive on a q-tip. I used what I had on hand, automotive rubbing compound, the red paste. It did more to help accuracy than anything I've tried so far. I shot about 25 q-tips with a CP 10.5 behind it. It is looking like it wants to group. 5 shots out of 10 are touching. I'll lap it some more when I have time and try different pellets. This is encouraging! I'm going to try this on some other barrels.

Jon

K.O. · « **Reply #32 on:** November 12, 2014, 03:33:45 PM »

Thanks Josh I can see how the jsb and some longer pellets may help in some cases...

I was approaching it fron Fixxing the problem angle not hey this pellet just might smooth things out...

I think Jon should push a pellet thru from the muzzle side and see what the high & low spots feel like in comparison to the choke...

then start marking the spots running pellet thru from both directions until it is well marked and a very good feel and understanding of the tight spots is obtained

if it is more than .1"-.4" tight spots then a bore mop or tight patch(if smaller spot than the mop) with the bore paste and work that area by hand. tedious but cheating with very fine wet dry is a touch risky...

It all depends on what he feels when he pushes the pellet thru from the choked end how loose are the loose spots and how tight are the high spots...

so there is my reasoning. anything is worth a try and I had much rather buy a $14 tin of pellets and have a chance they may shoot well enough than to invest more time and money in a gun that's worth $250 at best.

Josh Tinkering is part of the attraction for some of us and we do not care for $
Sometimes we get to learn a new method or come up with one...

From having read some of Jon's posts I think he likes working on these things...

take a look at Jasons(nervous triggers 7 page journey about fix or just change a barrel In the end he gained a feel... and also had a(frustrating at times) journey at the same time...

Thanks again, I did fail to see it from the angle you did, it might even help this barrel, but shot to shot consistency might be bad enough to prevent it, imo.

K.O. · « **Reply #33 on:** November 12, 2014, 03:39:01 PM »

oops Jon posted while I was typing ( I am very slow)...

Jon take a little time to get to know your barrels first... I would say more but have to take my sons Manx to the vet ...

K.O. · « **Reply #34 on:** November 12, 2014, 03:56:49 PM »

It is easy to over do fire lapping deciding what you have and when to stop is the trick...

TooJung2Die · « **Reply #35 on:** November 12, 2014, 04:46:09 PM »

Quote from: K.O. on November 12, 2014, 03:56:49 PM

It is easy to over do fire lapping deciding what you have and when to stop is the trick...

I understand. Too much of a good thing...
I had to try some boxed CPDL. All within .75" at 25 yards, most touching the same hole. Those high fliers in the previous target were loose fitting CPDH tin pellets. I'm beginning to feel like this barrel may have potential.

TooJung2Die · « **Reply #36 on:** November 15, 2014, 11:40:37 AM »

It was suggested to me that rubbing compound is too soft and I should try something more abrasive. Trying to use only what I have on hand I used white Colgate toothpaste, followed by JB bore compound. After thoroughly cleaning barrel I got this 1/2" 6 shot group at 25 yards. This air rifle is beginning to behave like a Diana with five out of six touching and the ubiquitous flier. I won't have to replace the barrel after all!

I think the stock deserves to be refinished. Yay!

Jon

K.O. · « **Reply #37 on:** November 15, 2014, 03:01:29 PM »

Tater · « **Reply #38 on:** November 15, 2014, 08:41:23 PM »

Glad to hear it's working better now Jon.

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Bad Crown on a Choked Barrel - Ideas?

Author Topic: Bad Crown on a Choked Barrel - Ideas? (Read 10713 times))