Shift in Zero: Diagnosis?
- Thread starter 5RWill
- Start date
Some 'smiths think full contact barrel bedding all the way to the fore end tip is best. The one's I heard that from say they want all the support possible under the barrel to hold it up so it doesn't droop down at the muzzle.
Or, other 'smiths wrap 1/16" tape around the barrel then put epoxy in the fore end barrel channel. The barrel's free floated that way but never could figure out why that was done in the first place.
Or, other 'smiths wrap 1/16" tape around the barrel then put epoxy in the fore end barrel channel. The barrel's free floated that way but never could figure out why that was done in the first place.
Here's a little excerpt on his method.
http://www.billscustomautomatics.com/process.html
What manufacturer? I guess that's my case i just hate that it's there..
http://www.billscustomautomatics.com/process.html
4runnerman said:
What manufacturer? I guess that's my case i just hate that it's there..
4runnerman
New member
Blackops- Mine was a UTG that I put on my 223. Still holds zero perfect,but have to deal with the spec inside. If this is youur case as well What will happen is all of a sudden on one shot it will fall off inside of glass and be gone for how ever long and then pop up again some place else, or not show up at all again. It really ( after you get used to it ) is not a big deal,depeding on where it sticks to the glass. UTG was going to warranty it 100%,but so far it has not really bugged me to much.
What has been your experience? Mine is that every bolt action that I free floated the barrel shot better afterwards. I asked one of the Club's Graybeards the same question and he had one that maybe shot better with barrel bedding.
Based on what I have read, it was the fashion to full length bed barrels. Here is what Elmer Keith said in his book "Keith's Rifles for Large Game."
I never had any use for "floating" barrels; they are simply a cheap substituted for proper wood and perfect bedding.
When you have authority figures of the stature of Elmer Keith proclaiming the virtues of fully bedded barrels, no wonder those who can’t shoot straight think they are the cat’s meow.
Slamfire, Keith's right. Because a bolt action magnum Mauser in .505 Gibbs was/is a tack driver at 65 yards shooting 2 MOA is a tack driver. Enough to silence the meows of tigers and lions.
Lots of full barrel channel bedding was done when epoxies were first used.
Many bolt action rifles decades ago had a screw through the fore end holding it tight against the barrel. 'Twas done believing constant pressure against the barrel improved accuracy. It worked if pressure was constant and in the same axis for every shot. But it wasn't and still isn't today.
Lots of full barrel channel bedding was done when epoxies were first used.
Many bolt action rifles decades ago had a screw through the fore end holding it tight against the barrel. 'Twas done believing constant pressure against the barrel improved accuracy. It worked if pressure was constant and in the same axis for every shot. But it wasn't and still isn't today.
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tangolima, shimmed up barrels often shoot more accurate when the barreled action's poorly fit to the stock. I've had a couple of those.
But there's no way the pressure on the barrel will remain constant across all shooting positions. My rifles that had that issue had different zeros on the sights for different shooting positions.
But there's no way the pressure on the barrel will remain constant across all shooting positions. My rifles that had that issue had different zeros on the sights for different shooting positions.
Both rifles have been glass bedded. In fact glass bedding an smle is moot because of its 2-piece stock. Both of them are fitted as well as I could possibly do.
Shimming on mosin is very common. Smle is more sophisticated. It has adjustable upward and downward pressure points built into its stock.
I don't see noticeable change in poi with different shooting positions. My non-shooting hand always support the rifle right under the chamber, where the wood is always in full contact with the action. I was worried about shift in poi as the gun heated up. It turned out no bad. I believe it is because the forearm is also reinforced with bedding compound.
I am a firm believer of free floating barrel. It works well for me in most rifles I have. It is always the first method I try to accurize a rifle. Only a few need shimming, and I believe it is a well documented common practice for those rifles.
-TL
Shimming on mosin is very common. Smle is more sophisticated. It has adjustable upward and downward pressure points built into its stock.
I don't see noticeable change in poi with different shooting positions. My non-shooting hand always support the rifle right under the chamber, where the wood is always in full contact with the action. I was worried about shift in poi as the gun heated up. It turned out no bad. I believe it is because the forearm is also reinforced with bedding compound.
I am a firm believer of free floating barrel. It works well for me in most rifles I have. It is always the first method I try to accurize a rifle. Only a few need shimming, and I believe it is a well documented common practice for those rifles.
-TL
0.5 moa? They are rifles of almost 100 years old, and they have iron sights. I am no match winning, record breaking rifleman either. I can't possibly do such small group even in my sweetest dreams.
Before shimming the group was like 6 moa. After shimming I got 2 moa. I was shooting on bench rest. Certainly I had to monkey with the sights to re-zero after the shims. Then I tried shooting them in sitting and prone positions. The groups became 3 to 4 moa because of my limited marksmanship skill. But the centroid of the groups didn't seem changed.
-TL
Edit: Sorry I misread your post, Bart. You didn't mean 1/2 moa group, but 1/2 moa deviation from call. I am afraid I can't do that either on iron sight. If I can call 2 or 3 moa I am doing super good already. I just aim at the center of the target and fire 10 rounds. The centroids of the groups are within 1 moa from each other. I don't sling up when I shoot either.
Before shimming the group was like 6 moa. After shimming I got 2 moa. I was shooting on bench rest. Certainly I had to monkey with the sights to re-zero after the shims. Then I tried shooting them in sitting and prone positions. The groups became 3 to 4 moa because of my limited marksmanship skill. But the centroid of the groups didn't seem changed.
-TL
Edit: Sorry I misread your post, Bart. You didn't mean 1/2 moa group, but 1/2 moa deviation from call. I am afraid I can't do that either on iron sight. If I can call 2 or 3 moa I am doing super good already. I just aim at the center of the target and fire 10 rounds. The centroids of the groups are within 1 moa from each other. I don't sling up when I shoot either.
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hunttheevil
New member
Subscribed! I am interested to see how this turns out. Blackops2 has identified 3 variables to this rifle. All 3 variables could have an impact on POI, or it could be one issue.
Shot today it's still high about 2/10ths. Though lower than it was before. I went ahead and adjusted my zero. Though i'm seriously starting to think it's fouling. Going to run these 15rds out to 725yds to get some DOPE before this tournament, load about 100rds and we'll see what happens. If it is the scope my Mark 6 is in. About to have some 34mm rings on the way.
hunttheevil
New member
I doubt it is the scope. Tightening the action screws probably had the biggest effect. The removal of copper fouling generally opens up the grouping until 5 to 10 rounds have been fired through the rifle. After 5 to 10 rounds, a base layer of copper fills the micro striations and the group tightens back up. I think this is indicative in the first target you posted. I'm guessing you shot first which laid the copper in the barrel, and your buddy shot second which yielded a tighter group.
If you're still shooting the ammo that is 100 FPS from what the rifle was originally set with that could be the current difference. I took a 165 grain, 308 cal., with an MV of 2700 and a BC of .446. I changed the MV 100 FPS in a ballistic calculator and the difference in bullet path was 2/10ths of an inch. Hopefully if you get to shoot at 750, before your next match, the rifle will do its job.
If you're still shooting the ammo that is 100 FPS from what the rifle was originally set with that could be the current difference. I took a 165 grain, 308 cal., with an MV of 2700 and a BC of .446. I changed the MV 100 FPS in a ballistic calculator and the difference in bullet path was 2/10ths of an inch. Hopefully if you get to shoot at 750, before your next match, the rifle will do its job.
Merrill Martin also had a theory he called "carbon tunnel syndrome" in which he believed it was carbon evening out friction in a bore that was responsible, rather than copper. IIRC, he found it true in .22 Rimfire rifles, too. In support of that, it's long been conventional wisdom among target shooters that if you change loads in a match to one using a different powder, even without cleaning inbetween, you can expect it to take about 10 rounds for the zero to settle completely.
Tried to go resize, trim, and tumble tonight. Couldn't get a hold of my buddy. Still have 15rds to get some DOPE with. I think it will be alright, i guess it just perplexes me that the same load and a load 1/2 a grain hotter shot bullseye, now shoots high. Then again who's to say i'm shooting the same, we had the lose action screw, clean bore, and that was a year ago.
When i load this time i wont be rushing things just to have rounds. My ES and SD was way to high on these last seven that i chronoed.
600 is where my limited experience starts to show. 500 at least with my Berger 175gr BT LRs i could hold MOA and under all day. 600 i would vary and i've never passed 600. I'm not expecting to shoot well due to my inability to read wind as of now, and i never shoot alternate positions. Lol been practicing dry firing.
Here's what I'll be up against. Gets my adrenaline going just thinking about it
When i load this time i wont be rushing things just to have rounds. My ES and SD was way to high on these last seven that i chronoed.
600 is where my limited experience starts to show. 500 at least with my Berger 175gr BT LRs i could hold MOA and under all day. 600 i would vary and i've never passed 600. I'm not expecting to shoot well due to my inability to read wind as of now, and i never shoot alternate positions. Lol been practicing dry firing.
Here's what I'll be up against. Gets my adrenaline going just thinking about it
Maybe the adrenaline is the problem? I remember years ago, when Harlon Carter was still National Conventional Pistol champion, a reporter at the Nationals asked him why nobody at the match seemed very excited. Carter replied that when a pistol shooter feels a fit of excitement coming on he goes and lies down until it passes. I find the same applies to getting good rifle scores. Nothing like an adrenaline twitch to throw a monkey wrench into the mix.
Maybe. I used to drink a soda and dip on the ride out to the range and it made my heart rate sky rocket. Stopped for that reason. I haven't really felt nervous behind a rifle in a while though not like i used to be. I can sit calmly behind my rifle and fall back on fundamentals now a days. I'm not too worried anymore for whatever reason it changed.
