Another try at eliminating the first round low shot in MTR

[Joe L]

Last time out with the MTR, the first round of each 5 round magazine sequence hit an inch or two lower than the remaining 4 rounds at 100 yards from a rest.  When I got home, I cleaned the bore lightly with solvent and patches, ran one oiled patch and put the rifle in the safe.  Today, I pulled the rifle out, ran a few dry patches to eliminate the oil, then borescoped the chamber area.  Sure enough, there was an uneven ring of carbon just upstream of the rifling in the chamber area.  Next, I brushed the chamber area, ran one VFG aggressive pellet back and forth, then a few dry patches and borescoped the area again, the carbon ring was gone.  Here is a short video showing before and after.
https://youtu.be/B8NwqlcaPt0
I will shoot the MTR again on Thursday and confirm this carbon ring was the problem.  I've seen this before, when I was too lazy to REALLY clean the chamber area.  Seems to build up in about 100 rounds.  More on Thursday afternoon.
Joe

[Peashooter67]

Target chambers form a rings much faster or affects accuracy sooner than in a sporter chamber.


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[AZ_CZ]

Any explanation for this pattern? What happens when you use a 10 rnd mag; 1 low 9 tight? What if you used a single shot adapter; do they all shoot the same? (Use to shoot with a guy and it’s the only why he’d shoot for accuracy). Can’t wait for the next episode.

[Joe L]

Target chambers form a rings much faster or affects accuracy sooner than in a sporter chamber.

Yep, I'm thinking this is the explanation.  I never had this show up on the Kadet.  Thanks
Joe

[Joe L]

Any explanation for this pattern? What happens when you use a 10 rnd mag; 1 low 9 tight? What if you used a single shot adapter; do they all shoot the same? (Use to shoot with a guy and it’s the only why he’d shoot for accuracy). Can’t wait for the next episode.

Good question.  First round, each magazine, whether 5 or 10 from what I remember.  But only if I didn't use a brush and some JB Bore paste or a VFG pellet when I last cleaned it.  I've been using the 5 round lately just to slow me down some.  I'm guessing the ring hardens back up some while I am reloading the magazine, but the amount of heat buildup and the amount of cooling has to be different between a 5 round and a 10, but then so is the time to reload the magazine. 

I may take a pistol length rod and a vfg pellet with me on Thursday to clean the chamber after 50-100 rounds or so and see if I can stop the first round flyer when they start appearing again.

It is a lot easier for me to predict what is going to happen with a 9mm CZ pistol at 200 yards than a CZ match chamber .22 at 100 yards.  Dang rimfires, can't live with 'em, can't live without 'em. 

[Peashooter67]

Just remember that when it stops being fun and you lose your enjoyment that it’s time to take a break.


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[skin]

 I've found that the coating on the ammo the culprit. Wax type coating to cause the dreaded ring to appear sooner than the oil type coating. If I shoot a lot of eley, I have to clean right after shooting. Sk ammo takes longer in my barrel. Luckily my rifle likes sk ammo.

[AZ_CZ]

Dang rimfires, can't live with 'em, can't live without 'em.

That’s the truth! Only rimfire I shoot past 50 yards anymore is my 17m2. After that I switch to 223, 6.5, or 308. Unless you shoot top-tier ammo the velocity standard deviation just drives me nutty.

[George16]

I've found that the coating on the ammo the culprit. Wax type coating to cause the dreaded ring to appear sooner than the oil type coating. If I shoot a lot of eley, I have to clean right after shooting. Sk ammo takes longer in my barrel. Luckily my rifle likes sk ammo.

I found the same thing. Unless it’s copper coated, the ammo gets tumbled in corn cob to remove the wax coating. So far, it has helped in preventing quick buildup of crap in my 457 Varmint.

[Joe L]

I've found that the coating on the ammo the culprit. Wax type coating to cause the dreaded ring to appear sooner than the oil type coating. If I shoot a lot of eley, I have to clean right after shooting. Sk ammo takes longer in my barrel. Luckily my rifle likes sk ammo.

I found the same thing. Unless it’s copper coated, the ammo gets tumbled in corn cob to remove the wax coating. So far, it has helped in preventing quick buildup of crap in my 457 Varmint.

Another good point.  I'll be shooting SK Rifle Match on Thursday.  I think that is what I was shooting last time out also.  I had inconsistent results in the MTR with the Norma Match, but the Kadet pistol loves the stuff. 

[Joe L]

Shot 50 rounds of SK Rifle Match at 100 yards today in good conditions.  Cleaning the chamber area eliminated the first round low fliers but I couldn't shoot a good 5 shot group.  I'm thinking the rest of the barrel is fouled also, so I will try a "deep" cleaning with the brush/solvent/VFG pellets and try again on Tuesday.  Some progress I suppose, but not good enough at 1-2" groups for 10 groups.

But, I needed the trigger time and a refresher on how to set up all the video equipment.  All I forgot today was to manually focus the camera at the target and to hit record on the shooter audio recorder.  So blurry video with no sound.  You all will never see it.  But I could still see every shot and confirm the first shots of each magazine were NOT low.  I had to go to the range at noon instead of at 9am and there were plenty of folks there.  So, I got in a hurry trying to minimize the cold range interruptions. 

Joe

[skin]

 Any updates?

[Joe L]

No.  I've been working on other photo/video projects instead of shooting.  Too many cold and/or wet spells here locally and some family member health issues and a wedding to tend to also.  I've taken a month off, without really intending to.  But I do have a range session scheduled for tomorrow with the MTR and SK Rifle Match. 

[Joe L]

Shot 100 rounds of SK Rifle Match this morning after a thorough chamber cleaning a few weeks ago.  First 50 rounds, each 5 shot group would have 1 flyer, when I went to 10 shot magazine for the second 50, the groups tightened up and the flyer was gone for the last 2 ten shot groups.  I am not going to clean it.  I am just going to go back to the range on Friday or Tuesday and shoot another 100 rounds without touching it and see if the groups are stabilized.  If so, I'll not clean it until they open up again or the flyers reappear. 

Other than forgetting how to count to 10 and forgetting a tripod and camera battery, it was a good day.   

Seriously, it was a good day, got to visit with my shooting buddies, and no mud or cold to cope with, just the normal .22 rifle challenges. 

Joe

[skin]

 How were the groups? I hope to get to the range next week. Nice day to go shooting!