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I wanted to use ski feet on a bi pod but I don’t have an adapter for the front stud to attach a picatinny rail. I might order one? This is a real nice rifle so I don’t want to do anything that may hurt the collector value.
November 7, 2015
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I noticed BACO was using something akin to hot glue on the recoil lug of a late M70. I don’t know how effective it may be as they bedded the recoil lug and rear tang during a subsequent warranty repair. Hot glue would be easy enough to remove. OTOH I’m betting it will settle down and shoot just fine without modifications.
Mike
Here is a picture as it is configured as of today. The white line along the barrel is from the flash.
I shot the Model 70 today using the scope. I removed the bolt and looked through the barrel so I could line it up with a target at 50 yds. Without moving the rifle I adjusted the scope to the center of the target. Well I at least hit the target with the first shot. Took me about 6 shots to move the POI right then down. Next 6 shots hit in a 3″ circle. My next 2 shots touched each other. Then something weird happened. The next 4 shots went 1″ then 2″ low. I shot 6 more shots working my way up. I had to stop shooting because I had an appointment to pick up my Model 75 Sporting.
As I was adjusting the scope I also shot 8 groups from 54.6 grains to 56 grains looking for nodes. 6 of the 8 loads shot as expected but 2 actually went down? I’m going to have to shoot these 2 over.
I don’t know why my point of impact changed? I will go over everything to see if the scope became loose.
Found that I had not mounted the scope properly and it worked loose. I prepared the cases that I shot on Tuesday. I will re shoot 3 powder charges and continue shooting the remaining loaded cases. It is suppose to get hot next Tuesday so I hope I can get the shooting done first thing in the morning. As usual I cleaned the copper out of the barrel. With fingers crossed, it appears to be less than before.
Chuck,
You sure had me wondering about that the other day, and I really didn’t want to suggest, what you found. I didn’t think it would sound right. I’m glad that you got it figured out, as it takes a big man to admit that. IMO! I really feel there’s an art to mounting a scope properly, and a lot of double checking goes into it. So many experts out there and many opinions on the subject as I try not to go there, and become one of them. I’ve just been lucky with mine, that’s all. Glad you got it worked out. 
Anthony
November 7, 2015
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Glad you got your scope mount issue straightened out, Chuck. I knew it was a mechanical issue from your description but quite honestly was worried that it might have been a stock issue. Scope rings/mounts are always suspect, I forget that sometimes they need to be checked after shooting a bit as a few have a tendency to “settle in” and loosen up even when properly torqued at installation. I’ve only run into it a few times but I know it happens!
Still too cold to shoot here in N Texas so carry on so I can enjoy it vicariously!
Mike
Mike, supposed to be in the mid 70’s next Tuesday when I shoot. I wish it would have stayed in the 60’s for another week. First firings were in the 50’s. Last week it was in the 60’s. Higher temp can cause a higher speed.
November 7, 2015
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Chuck said
Mike, supposed to be in the mid 70’s next Tuesday when I shoot. I wish it would have stayed in the 60’s for another week. First firings were in the 50’s. Last week it was in the 60’s. Higher temp can cause a higher speed.
Finally got out of the teens today, may get above freezing tomorrow. Way too cold for Texas!
Mike
TXGunNut said
Chuck said
Mike, supposed to be in the mid 70’s next Tuesday when I shoot. I wish it would have stayed in the 60’s for another week. First firings were in the 50’s. Last week it was in the 60’s. Higher temp can cause a higher speed.
Finally got out of the teens today, may get above freezing tomorrow. Way too cold for Texas!
Mike
My friend in Montana sends me pictures of his thermometer. -37 the other day and was even colder a few days before that. He went over a week without his main heater. The other one only warms the bedrooms and bathrooms. He went out and bought 2 space heaters and a load of fire wood. He and his dog cuddled up and made it through.
Here is something done by a person way smarter than I.
Is Barrel Break-In Real?
Yes, barrel break-in is a real phenomenon, but its significance depends on barrel manufacturing quality, rifling method, and surface finish. The goal of barrel break-in is to smooth out microscopic imperfections inside the bore and achieve consistent bullet behavior.
What Happens During Barrel Break-In?
A brand-new barrel, especially from mass production, has tool marks, microscopic burrs, and uneven surfaces from machining and rifling. These imperfections can:
- Increase copper fouling.
- Cause inconsistent bullet engagement with rifling.
- Affect gas seal and velocity consistency.
Over time, bullets and cleaning cycles help smooth out these imperfections, leading to:
[Image Can Not Be Found] Less fouling buildup.
[Image Can Not Be Found] More uniform gas seal around the bullet.
[Image Can Not Be Found] More consistent velocities and group sizes.
Does Every Barrel Need Break-In?
- Hand-lapped match-grade barrels (e.g., Krieger, Bartlein, Brux) → Minimal break-in needed since they are already polished.
- Factory barrels (e.g., Remington, Savage, Tikka) → May benefit from a controlled break-in process.
- Button-rifled barrels (e.g., Shilen, Criterion) → Can have more tool marks than cut-rifled barrels, requiring break-in.
How to Break In a Barrel
A common method is:
- Fire 1 shot, clean (repeat for 5-10 rounds).
- Fire 3-shot groups, clean (repeat for 5 groups).
- Fire 5-shot groups, clean (repeat 2-3 times).
- Continue normal shooting and monitor fouling behavior.
If fouling decreases after 10-20 shots, the barrel is smoothing out. If the rifle still coppers heavily after 50+ rounds, lapping or polishing might be needed.
What Causes Point of Impact (POI) Shift?
Several factors can shift the POI, even if a rifle is dialed in.
1. Barrel Heat and Stress
- As the barrel heats up, the metal expands unevenly, causing a slight bend or warp.
- This is more pronounced in light-profile barrels compared to heavy barrels.
- Stainless steel barrels tend to resist POI shift better than chrome-moly barrels.
[Image Can Not Be Found] Test by shooting a cold-bore shot vs. a hot-barrel group.
2. Fouling Accumulation (Carbon & Copper)
- Carbon fouling near the throat changes bullet seating depth dynamically, affecting pressure and velocity.
- Copper fouling alters barrel friction, impacting velocity and consistency.
- Some barrels “settle in” after a few fouling shots and shoot best when lightly fouled.
[Image Can Not Be Found] Monitor accuracy trends before cleaning. Some barrels shoot best slightly fouled.
3. Stock and Action Torque (Harmonics)
- If action screws are loose or torqued inconsistently, the stock-to-barrel interaction can shift POI.
- A change in bedding (e.g., pressure on the barrel channel) alters harmonics.
- Free-floating barrels usually shift less than those with pressure points.
[Image Can Not Be Found] Check torque values and bedding contact points.
4. Scope and Mounting Issues
- Loose rings, improper torque, or optic movement causes drift.
- Temperature shifts can affect reticle zero, especially in lower-end optics.
- Parallax errors at different distances can also cause apparent POI shifts.
[Image Can Not Be Found] Check mounts and confirm parallax adjustment.
5. Ammunition Variability
- Changes in bullet seating depth (jump to lands) shift POI.
- Powder temperature sensitivity alters velocity.
- Different lot numbers of the same ammo can have slight variances.
[Image Can Not Be Found] Test loads under different temperatures and lot numbers.
Key Takeaways
- Barrel break-in helps smooth imperfections but is more critical in factory barrels than custom match barrels.
- POI shifts can result from heat, fouling, harmonics, scope issues, or ammo inconsistencies.
- Monitoring trends (cold bore vs. hot groups, fouling patterns, and torque values) helps diagnose shifts effectively.
November 7, 2015
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Chuck said
TXGunNut said
Chuck said
Mike, supposed to be in the mid 70’s next Tuesday when I shoot. I wish it would have stayed in the 60’s for another week. First firings were in the 50’s. Last week it was in the 60’s. Higher temp can cause a higher speed.
Finally got out of the teens today, may get above freezing tomorrow. Way too cold for Texas!
Mike
My friend in Montana sends me pictures of his thermometer. -37 the other day and was even colder a few days before that. He went over a week without his main heater. The other one only warms the bedrooms and bathrooms. He went out and bought 2 space heaters and a load of fire wood. He and his dog cuddled up and made it through.
Even with all new windows and two new doors my house is built for Texas weather. I have a few space heaters but only needed one. i had to adjust my vents as the warmest rooms in my house were my loading room and guest bedroom. Roofing contractor hasn’t finished the install on my chimney so fireplace was not an option. Probably should have pulled out the fireplace and put in a stove. Things around here would cease to function before we reached -37. Community well went down last night but I did a little extra work last time my pipes froze so I am OK.
Mike
I changed out the front bipod today. I installed an adapter to the swivel stud so I can use a better, more stable and will slide on the bench. Hopefully this will reduce some of the barrel jump.
I shot 37 rounds yesterday to finish my powder ladder testing. I now have fired 3 rounds at 54.6 grains to 59.6 grains in .2 grain increments. I will post the results later.
The adapter that I tried to use for the bipod came loose. I had a real hard time getting it installed tightly in the first place. I will have to deal with it again. The wider bipod with the ski feet did help some with stability, tracking and barrel jump. This light rifle has a lot of recoil and barrel jump. I messed up my hold a couple of times and I now have a red and sore spot on my collar bone. I guess my T shirt was not enough padding. It was 73 degrees.
I crunched all the numbers and I’m going to test 5 shot groups at 54.9 grains, 55.9, 56.1, 56.7, 56.9, 57.5, 57.7 and 58.9. I did not use the slowest nodes or the fastest nodes. If I were a hunter and thought I might need the extra speed I might, and I stress might, go one higher. But I see no need to go 3,000 fps. The 58.8 may get me there depending on the ambient temperature. At 3,000 fps I’m still under Book Max for this bullet and powder.
I can not explain the math but when you find a node that works real well you can almost always find another load 3% higher powder charge or lower that will work too. This works for 1.5% also. Be aware that only one will work best. Either the 1.5% or 3%. Your groups will tell you which one.
I loaded 49 rounds. I ruined one the other day. I loaded the previously stated nodes, 5 rounds each except the first one. I loaded 14 of these. I have been shooting at 50 yards and want to move out to a 100. I need a few rounds to warm the barrel and a few more to get on the target. Hopefully 9 rounds is enough. Then the node testing can be done. I don’t want to shoot these too fast so it may take 2 sessions to get this part done.
I spent some time getting the adapter on the front stud so I can use a picatinny rail and a nice bipod. I hope it stays tight this time.
I was able to shoot 4 groups yesterday before I started playing with the Model 75 I bought recently. Not real happy with the results. All 4 of the 5 shot groups at 100 yds. were about 2″. Only one lacked the wide dispersion that the others showed. This was the lowest powder charge tested. I think I’m going to back up a bit and load some at the lower nodes and see if this will tighten the groups. Maybe I’m too fast for this bullet/barrel combo and need to stay closer to 2,800 fps? I know I haven’t found my powder charge or even got around to finding a bullet seating depth. I just don’t like what I’m seeing. I did buy some 130 gr. and 135 gr. bullets too. But I did not buy any flat based bullets. All of the ones I bought are modern boat tail bullets.
Had to play with the bipod adapter again. This time it was my fault. I forgot to tighten the 2 screws.
November 7, 2015
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Still using 4831 powder? I’ve always had such good luck with spitzer bullets that I seldom worked with BT bullets in anything bigger than .22’s so I’m no help there. Your project and another I’ve been reading about convinced me to replace/upgrade my failed Lyman borescope today. I decided since I haven’t figured out how to fix the light after 4-5 years I might as well move on. Now I need to get around to shipping my Labradar in for repairs. No room in my budget to replace it but I sure like that Garmin!
Mike
Mike, yes I am still using the H 4831 SC. I don’t want to change anything. If I do I would have to start over and re do the powder ladder testing.
What is wrong with your Labradar? I have had mine for about 5 years. I did have to replace the battery pack and the cord. The Garmin is real popular and much easier to set up. I’m not fond of the small screen. I’m not sure but I think it does not produce the down range energy figures that the 2nd page of the Excel spreadsheet does with the Labradar?
November 7, 2015
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Chuck-
I’ve only used that powder a time or two, was wondering how you selected it.
I have an early Labradar that works 70-80% of the time, will often fail to pick up a bullet. I thought maybe it was my old school lead bullets and lube smoke but a friend borrowed it to check some modern ammo and had same results. I just never have taken the time to return it for repairs. When I contacted them they were trying to figure out what I was doing wrong. Maybe I’ll have better luck this time. Do you have a contact there?
Mike
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