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+--- Thread: Groups opening up. (/showthread.php?tid=22482)
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Groups opening up. - Nimrod - 12-10-2020
Ive got a LBC with a 20 bull barrel. This rifle typically puts five in the same hole at 200 yards. Suddenly the groups have opened up to 1-1.5 with known proven loads. Barrel is clean, no copper. Everything is tight. Ive got probly 3000 rounds through it. Swapped scopes, 3 times. Dont know where else to look. Cant believe Ives shot the barrel out yet. Could it be bolt fatigue? No visible cracks or anything but it does appear to be slightly stretching....if thats even possible. Just looking for advice.
Groups opening up. - Lemonaid - 12-10-2020
A look in the barrel with a bore scope might tell you something. If the lands have eroded enough, having the ammo seated out a few extra thousandths might restore accuracy. I've read firing pins can make a difference so swap it out and see what happens?
Triple check scope mounts, screws, muzzle device for proper torque. Check barrel crown.
Groups opening up. - Klem - 12-10-2020
Nimrod,
Check your barrel nut and crown. Unlikely to be your bolt.
"Typically" shooting 5 rounds in the same hole at 200 (0.32MOA) is hard to believe. But a top-tier barrel should still be shooting 1MOA or less after 3K rounds. When it was new it was more likely 0.7 or 0.8MOA...wasn't it?
You'll need to fill that barrel with copper again or it definitely won't shoot.
Groups opening up. - Klem - 12-10-2020
1.5-2MOA after 3K rounds is normal for top-tier barrels. Your suggestion that an AR is capable of 'typically' shooting 0.32MOA at 200 is unbelievable.
It does not sound like anything is wrong with it.
Groups opening up. - Bigs28 - 12-10-2020
You said barrel is clean..... is that a new thing?
Groups opening up. - LR1955 - 12-10-2020
Nimrod Wrote:Ive got a LBC with a 20 bull barrel. This rifle typically puts five in the same hole at 200 yards. Suddenly the groups have opened up to 1-1.5 with known proven loads. Barrel is clean, no copper. Everything is tight. Ive got probly 3000 rounds through it. Swapped scopes, 3 times. Dont know where else to look. Cant believe Ives shot the barrel out yet. Could it be bolt fatigue? No visible cracks or anything but it does appear to be slightly stretching....if thats even possible. Just looking for advice.
One hole at 200 yards is typical performance?
I imagine the 200 yard bench rest record is something like one hole at 200 yards but it wasn't typical and wasn't shot with a .264 LBC or a 6.5 Grendel or from anyone on this forum.
Most guys who are really good marksmen here admit that half a minute is somewhat a rare occurrence with them and you are complaining that your rifle is poor giving 1/2 to 3/4 minute performance all the time at 200 yards?
A Bench Rest shooter with a lot of competitive experience and knowledge of equipment would say his barrel was shot out.
My bet is that you have a damn good rifle and gear and that it is doing exactly what high quality gas guns and gear do. Hold about a mean of about one minute at 200 yards with an SD of about 1/4 minute.
LR55
Groups opening up. - 37L1 - 12-10-2020
Am I the only one that wants to see all those "one hole" targets?
Groups opening up. - Mesa1978 - 12-10-2020
37L1 Wrote:Am I the only one that wants to see all those "one hole" targets?
Nope. Would love to see those amazing groups.
Groups opening up. - Nimrod - 12-10-2020
LR1955 Wrote:One hole at 200 yards is typical performance?
I imagine the 200 yard bench rest record is something like one hole at 200 yards but it wasn't typical and wasn't shot with a .264 LBC or a 6.5 Grendel or from anyone on this forum.
Most guys who are really good marksmen here admit that half a minute is somewhat a rare occurrence with them and you are complaining that your rifle is poor giving 1/2 to 3/4 minute performance all the time at 200 yards?
A Bench Rest shooter with a lot of competitive experience and knowledge of equipment would say his barrel was shot out.
My bet is that you have a damn good rifle and gear and that it is doing exactly what high quality gas guns and gear do. Hold about a mean of about one minute at 200 yards with an SD of about 1/4 minute.
LR55
Not complaining, but I know my rifle and I know how I shoot and there has been a significant shift. I might have been stretching the one hole groups a tad, counting out the cold bore or occasional flyer but not by much. Im a fan good shot and my rifle is also, or was. Its giving my groups at 300 that it used to do at 500. And 1-1.5 at 200 is terrible for it and me. Ill drop some pics of my one hole groups later when I get to my computer.
Groups opening up. - A5BLASTER - 12-10-2020
Nimrod Wrote:Ive got a LBC with a 20 bull barrel. This rifle typically puts five in the same hole at 200 yards. Suddenly the groups have opened up to 1-1.5 with known proven loads. Barrel is clean, no copper. Everything is tight. Ive got probly 3000 rounds through it. Swapped scopes, 3 times. Dont know where else to look. Cant believe Ives shot the barrel out yet. Could it be bolt fatigue? No visible cracks or anything but it does appear to be slightly stretching....if thats even possible. Just looking for advice.
What was the air temp? Humidity? Dew point? Barometric pressure?
Was this the first time shooting those loads at that air temp?
Also check your jump to lands, could be your barrels throat has moved enough too put your jump to long and the group starting to open.
Groups opening up. - Nimrod - 12-10-2020
[ATTACH=CONFIG]17270[/ATTACH][ATTACH=CONFIG]17269[/ATTACH][ATTACH=CONFIG]17268[/ATTACH][ATTACH=CONFIG]17267[/ATTACH]
Yea the one hole was a stretch but this rifle usually stacks them up. It doesnt anymore. Thanks for all the great meaningful advice fellas. Really big of you.
Groups opening up. - Nimrod - 12-10-2020
A5BLASTER Wrote:What was the air temp? Humidity? Dew point? Barometric pressure?
Was this the first time shooting those loads at that air temp?
Also check your jump to lands, could be your barrels throat has moved enough too put your jump to long and the group starting to open.
I did check my runout to the lands, it seems extreme, but I dont know what it was when I bought it. Right now it is .105 which seems extreme. Not sure about all the weather variations.
Groups opening up. - Nimrod - 12-10-2020
Klem Wrote:Nimrod,
Check your barrel nut and crown. Unlikely to be your bolt.
"Typically" shooting 5 rounds in the same hole at 200 (0.32MOA) is hard to believe. But a top-tier barrel should still be shooting 1MOA or less after 3K rounds. When it was new it was more likely 0.7 or 0.8MOA...wasn't it?
You'll need to fill that barrel with copper again or it definitely won't shoot.
Your saying it will improve after I foul it?
Groups opening up. - TexHill - 12-10-2020
Nimrod Wrote:Your saying it will improve after I foul it?Yes he is. This phenomenon has been known by competitive benchshooters for a very long time. They never go into a match with a rifle that has just been cleaned.
They also don't clean their rifles until their groups start to open up.
Groups opening up. - jasper2408 - 12-10-2020
Do a ladder test to see if the node has moved on you.
Groups opening up. - biodsl - 12-10-2020
Nimrod...I have a 22" BHW in 264LBC. It's been my experience that after I remove the copper from the barrel it takes 50 to 80 rounds for it to start shooting well again. Shoot it a bit and see what happens.
Groups opening up. - Nimrod - 12-10-2020
Ok, thank you guys. I did do a ladder test, and the node for vertical dispersal seemed to be the same. Ill run some more through it to see if it tightens up. Its odd that Ive never experienced this though. Ive shot this old girl a bunch and and Ive cleaned the hell out of it before and never had trouble.
Groups opening up. - TexHill - 12-10-2020
Nimrod Wrote:Ok, thank you guys. I did do a ladder test, and the node for vertical dispersal seemed to be the same. Ill run some more through it to see if it tightens up. Its odd that Ive never experienced this though. Ive shot this old girl a bunch and and Ive cleaned the hell out of it before and never had trouble.Over cleaning can cause just as much or more wear on a barrel as shooting does. With today's modern, non-corrosive powders there is really no reason to clean your rifle after every trip to the range.
The military cleans after every time that they shoot their weapons for 3 reasons: tradition; it's good busy work for privates; and the unit armorer doesn't want to have to clean all of the rifles himself should he have a surprise inspection.
In this episode of the Primary & Secondary podcast, the 82nd Airborne's Small Arms Master Gunner discusses this very topic:
https://overcast.fm/+Jdwz6OlLs
Groups opening up. - Nimrod - 12-10-2020
[ATTACH=CONFIG]17271[/ATTACH][ATTACH=CONFIG]17273[/ATTACH][ATTACH=CONFIG]17272[/ATTACH]
Ill be, look what happened when I got it dirty again finally. Thanks for the advice fellas.
Groups opening up. - Klem - 12-10-2020
Nimrod,
Yes, you need all the pores filled with copper to smooth that barrel. A better quality barrel will shave less copper from bullets. Just use a cleaner that strips carbon and not copper. Consider cleaning the barrel less. By all means clean the working parts but the barrel is a different kettle of fish.
Your jump to lands is normal. My longest jump to lands from rounds loaded to the max a mag will allow is the 130OTM @ 0.12". The shortest is the stubby bvullets like the 90TNT and 95VMax at .09 and .025 however this does not leave enough shank in contact with the neck for an auto loader so they get pushed further in. The best all rounders are the 123SST and 120NBT at .09". All bullets from an AR mag will have longer jumps than a bolt gun, unless you want to load them individually into the chamber - and what is the point of that. Bottom line, it cannot be helped and is all part of the equation that sees AR's shoot less accurately than a heavy precision bolt gun. In your case it is not jump to lands that have caused group blow out.