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  #16  
Old 05-30-2019, 08:36 AM
truckjohn

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That's a sweet rig. Very nice.

What did you find with the Marlin factory barrels that made them "uncertain"?
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  #17  
Old 05-30-2019, 03:52 PM
jfleisc

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Originally Posted by truckjohn View Post
That's a sweet rig. Very nice.

What did you find with the Marlin factory barrels that made them "uncertain"?
IMO, unless you have a rig that can really lock down a gun to a concrete bench at the range it is difficult to quantitatively measure (before and after) re-chambering on an otherwise stock 22. If you're going to go with a whole bunch of improvements (and see an obvious increase in accuracy) how can you say how much effect the re-chamber alone did.
Also, shortening (to rechamber) the barrel will change the harmonics which may better (or worse) suit your chosen ammunition.
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  #18  
Old 05-30-2019, 04:49 PM
truckjohn

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Ok. I thought you had run into some problems with the factory barrels like sloppy internal finishes, inconsistent diameters, wear, pitting, and the like.

I did a rough measurement of my factory chamber on my XT-22 - it's approximately 0.8" long from the mouth to the beginning of the rifling. That seems really long. The carbon ring that forms is *way* back from the rifling... Interestingly - the leade stays quite clean even when many shots with dirty ammo leaves a prominent crud ring.

But - is this good or bad? I suppose it could be good because the rifling itself doesn't really experience fouling.... BUT if it allows the bullet to tilt sideways a bit prior to engaging the rifling - it could be bad....
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  #19  
Old 05-30-2019, 07:02 PM
jfleisc

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Originally Posted by truckjohn View Post
Ok. I thought you had run into some problems with the factory barrels like sloppy internal finishes, inconsistent diameters, wear, pitting, and the like.

I did a rough measurement of my factory chamber on my XT-22 - it's approximately 0.8" long from the mouth to the beginning of the rifling. That seems really long. The carbon ring that forms is *way* back from the rifling... Interestingly - the leade stays quite clean even when many shots with dirty ammo leaves a prominent crud ring.

But - is this good or bad? I suppose it could be good because the rifling itself doesn't really experience fouling.... BUT if it allows the bullet to tilt sideways a bit prior to engaging the rifling - it could be bad....
Agreed; 'it could be bad'. That said I just helped a friend set up his tuner on an older Remington target rifle and even though it seemed remarkably accurate (for a 2 pound trigger) it seemed to have a very loose chamber. On the other hand I only use sub sonic match grade ammo that is usually "dripping" with lubricant and never seems to foul the chamber. In fact I rarely clean it during competition season because it always shoots worse until I get a good 15 rounds through it. Go figure.
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  #20  
Old 06-02-2019, 07:44 PM
truckjohn

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So I recently tracked down an accuracy issue where the barrel was over-lubing with several high quality ammo's. These are all expensive greasy and oily stuff like Eley, Wolf, SK, RWS, etc.

I am really curious whether this is an issue with Marlin microgroove barrels or if it's simply because the chamber is a mile long... My suspicion is that it's just the long chamber.

I haven't heard specifically of this - but I have heard a lot of people comment that plain Marlin microgroove barrels don't really shoot that well with the expensive ammo.... I have read a ton of comments that go along the lines of "Well, it doesn't really shoot any better with the so called match ammo than it does with stuff like CCI SV".... That's sort of what my barrel did - it would give me a glimpse of a teeny groups, then it would fall off to 2-3 moa or so....

What I figured out was to shoot 2 rounds of cheap HV ammo in between 5 round groups and they would stay small....

Bear in mind that this is a bone stock factory barrel with it's bone stock long long chamber... It's not a match chamber or a match barrel.

Would trimming it back 1/8" or so sort out this weirdness?
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  #21  
Old 07-04-2019, 10:06 AM
truckjohn

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So a brief update....

I picked up a very good looking 1994 Marlin 25n to go head to head with my xt-22...

One surprise relevant to this project/quest is that this particular 25n's chamber is noticeably narrower than my XT-22 chamber... You can feel Eley "Drag" as it chambers in the 25n while everything drops right into the XT-22 barrel. And the bullets that chambered tightly shot into very small groups - to the point where it was putting 2 or 3 or 4 shots on each target into the same hole...

The 25n is showing signs that when the bedding and trigger is sorted out - it may well out shoot this XT-22.

That's sort of an indication to me that my XT-22 could benefit from a tighter chamber....

So how to make that happen.... It's a shame Que is gone....

Last edited by truckjohn; 07-04-2019 at 10:11 AM.
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  #22  
Old 08-23-2019, 01:23 AM
dangerranger
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I have a couple of old Marlins with the Micro groove barrel that I have shortened and re chambered. I used a Bentz reamer. [ Its loose enough to be used in a semi auto 10 22, but tighter than a sporting chamber.] I have not had any feeding problems. I just have to be sure not to shoot CCI Stingers in them. I'd have to look back at my old notes but I only set them back 3/8". One other thing I did was to Knurl the barrel shank, to give it the tightest fit. I did not replace the cartridge guides, because I am not going to shoot shorts or longs through them. the results have been great! I would not be afraid to take them to a silhouette match.
The ones that the barrels were gone I relined to 17 Mach 2 , or re barreled with Green Mountain barrels [made for a 10 22.] To make them fit I only had to alter the shank and re cut the extractor groves.

I did this when I could find the old Marlins for $20 or very close. Most of the chamber problems were from dry firing. Some can be ironed out but others needed to be re chambered.

Did it turn them into bench rest guns? No. But I'd shoot them against any off the shelf 22 out there.

One thing about using a 10 22 based barrel is that you can use the cut that holds the barrel into the ruger receiver as a front hold down . Most of the marlins are only held into the stock with one bolt. The second bolt really stiffens them up.

I have shot in a couple of vintage matches. One gun I didn't change the outside looks at all. It's kind of fun to shoot a sleeper. DR
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  #23  
Old 09-24-2019, 06:35 PM
50Shifty
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Well it is a little work but it is fun work and maybe a winter project. This is what i do with any lower priced used 22 rifle , first clean the chamber really good and the bore put it on a bench and test different ammo then pick what it really likes.Next i remove the barrel from the action i have a way to measure the depth of the chamber but you don't really need to do that ,i then set the barrel in my lathe and start facing the chamber back maybe .010 at a time until the bullet just starts to touch the rifling then stop put a very slight radius at the chamber opening then turn the tennon back until your head space is in spec. Then turn the barrel around in the lathe and cut a target crown then install the barrel back into the action with loc-tite sleeve retainer no pins.Put the barreled action back into the stock and test ,then if you want pillar bed it then bed the action. I have done a few rifles this way and they really shoot great had one or two go from shooting a 1" group at 25 yds to shooting 1/4" groups.
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