marlin micro groove question

[K.L.O.sako]

i have a marlin 883 ss in .22MAG and it's a wonderful little gun. i've noticed a pattern though, after 20 or 30 rounds it starts to scatter the shot pattern a bit. nothing real detrimental, i've never missed an animal with this gun, but it is noticeable. i sight in at an inch high at 85 yards, and from a clean barrel it holds about 1.5" or better off of a rest, on hood of truck, with good wind. after it's dirty this spreads to 3" or worse depending on ammo. I thought it might be the barrel getting warm but the last time i shot it was 20 degrees outside and i had the same results. the barrel was barely warm after 50 shots. my 336 lever in 30-30 doesn't have this charecteristic and has gone a couple hundred shots before cleaning without lose of pattern. I was just wondering if anyone else with a small bore micro groove had the same problem with there's. is that just the way they are? do you think the little 30 and 40 grainers are getting kicked around in barrel by the residue. let me here your theorys.

 

[DMK]

Don't micro-groove barrels foul up really quick and you aren't supposed to shoot a lot of lead? ...or is it copper?

 

[K.L.O.sako]

Idon't know? theres not alot about them in the gun rags.

 

[SSN Vet]

from what I've gleaned off of THR (not measured myself)....the micro-groove barrels are a little looser. So when shooting lead in a micro-groove, folks recommend using .310 dia. bullets.

Neither my model 60 nor my 336 in .30-30 are scoped, so I don't attribute the quality of my groups to anything other than my ability.....

I put a Williams appeture sight on the 336 not long ago and am now re-loading my own....so hopefully when things warm up I'll have opportunity to shoot enough to tell the difference.....

 

[JMusic]

I've had quite a few Marlin rifles with Micro Grove. They will shoot both lead and copper just fine in rimfire. In center fire that is a different story. Marlin recomends using copper only in centerfires. They have recently changed to Ballard rifleing to cure this in their center fires.

In 22 mag I have the 922?? It is the camp rifle version semi auto. I found that shooting several types of ammo was needed to find which one works best. Mine will easily shoot several hundred rounds without any noticable difference. The lighter bullets in Federal and Winchester works best in mine. take care


Jim

 

[K.L.O.sako]

well i forgot to mention that everything i shoot is copper, no lead in the grooves. and i've shot about everything but RWS, too pricey

 

[JMusic]

What do your groups look like once they start to open up? Are they scattered or linear?

Jim

 

[rangerruck]

microgroove is ideal for 22 ammo. why? physics say less deformation, and bullet 'grabbing' as it goes down the bbl. So you have something going on here. Lets think, one is , even if you think it is not getting hot, it is, and you should not have to clean this bbl, hardly ever. so before you shoot it, put the piece of paper under the bbl, and check it for it's freefloating. then , once it heats up, and you start to notice the spread, take that SAME piece of paper, and check the freefloat again, see if you now have some new tight stock places. if you do , sand those spots down. Also , it sounds like you could be getting some copper fouling. I would check it out, when it is clean, and once it starts to spread, with a bore scope. you may have to use just a light on one end, and say some bifocals, or one of those skinny low powered rimfire scopes. See if you have any streaks of copper in the bbl. Also look at it , when it is clean, inside the bore, and see if you have any rough spots, where junk can 'hang up'. Lastly, after you have taken care of all the above, you may wanna slug the bore, and see how near the end of the bbl, the bore gets tighter. if it is very near the end of the muzzle, and then the muzzle opens up a hair, it is going to open up even more, once it warms. So you may wanna find that tight spot near the muzzle, and cut and recrown there.
i am ignoring any scope issues here.

 

[Duckster]

Personally, never had a problem;

I now have Marlin 885 SS .22 Mag and Marlin Lever Action .35 Cal. Both are micro groved and shoot great for me all day. Drop dead accurate.

 

[Jackal]

It is normal for a .22 mag to lose accuracy after 20+ rounds, since it is a very dirty cartridge.

 

[K.L.O.sako]

jmusic: mostly they just scatter like a small shotgun pattern. no real stringing



rangerruck: thats one thing i haven't checked yet. i'll try to get the stock off this weekend and check clearence

 

[dfaugh]

Interesting....

My .22LR Marlins dojust the opposite...It takes 30-40 rounds before groups tighten up...Then they shoot REALLY good groups for 300-400 rounds. I usually clean about then, as the action has gotten pretty dirty.

 

[.45Guy]

Whoa, cleaning a Marlin .22. I think my 25 is on a 7 year cleaning cycle!

 

[Davo]

in my 25n (.22 lr) it is actually very consistant after the first few fowling shots. The micro groove style is theoretically easier to clean and causes less bullet deformation.
I have noticed that microgroove .22's prefer copper washed/jacketed bullets.

 

[rangerruck]

thats right dfaugh, most 22's, like to be dirty, and this is especially true for marlins, pig dirty if they can get there. this lends itself to the microgroove process, in that any irregularities are covered by the filth, between the raised grooves, so there is less 'chatter' as the bullet slides down the bbl, riding only on the grooves. If anyone here has ever been on a waterslide, you achieve your fastest, and smoothest ride, by arching your back, and having only the heels of your feet , and your shoulders touching the slide on the way down. same principle.

 

[rockstar.esq]

So I've got an idea to help you get a longer shot string before it fouls. JB non embedding bore paste on a patch on a tight jag. Polish the bore with it and I think you'll find that you'll wring out more shots before the fouling builds up so much. BEFORE you begin, make sure of a couple of things.

1) That your cleaning rod has smooth rolling bearings to ensure that your jag follows the rifling.

2) That you mark the cleaning rod with a bit of tape so that you don't shove the jag out the muzzle by accident

3) That you take it slow and evenly. JB is abrasive however it's an uber smooth polishing paste as opposed to "grit". Even so, a bit of restraint is in order to make sure that you don't muck up your chamber.

4) That you take special care to remove ALL the junk left in the bore before you shoot it!


Another way less popular idea would be to use a moly bore treatment which should make powder removing much easier. If you can't find an appropriate paste/goop, you can make some by taking moly powder (the kind used for tumble coating) and mixing it with rubbing alcohol or Hoppe's #9. Get a sopping wet patch run down the bore and let it air dry. After a couple of minutes run another wet patch. Once dried, run a dry patch through the bore to remove any loose Moly. Keep a few things in mind. First Moly powder is a pale gray that gets into everything like charcoal so make it wet to control it better. Second, the dry patch will doubtlessly be blackish, once bonded to the metal, Moly won't come off without a solvent. I don't worry about leaving a little loose Moly in the bore because the first couple of shots will take care of that for me.

Either way I applaud you for paying such attention to your rifle's performance. Most shooters don't actually know when their rifle has fouled enough to reduce accuracy. Further I appreciate that you're taking a good attitude about hunting accuracy vs. target accuracy. The details can make it fun, the shooting is what gets it done.

 

[K.L.O.sako]

you know dfaugh, i've never let this gun get uber: dirty. i always clean it after a shoot or a day or two of hunting. i bought this gun used about october last year, still looks new though,( thats probably why i clean it too much ) l pulled the stock off like rangerruck suggested and nothing seemed to be amiss. i'll give your theory a try dfaugh and see what happens. thanks.