That's only going to be marginally stable at sea level. What level are you? My 6BR loves 105 but I also run a 7.5 twist barrel
105 Hybrid lost cause in 6BR?
- Thread starter VA_XTC_Shooter
- Start date
Thanks for the reply Bill. I shoot from sea level +2 feet in sunny Florida, to just below the Eastern Continental Divide in good old West “By Golly” Virginia, 3,000ft. In all cases, I am making round holes in targets at 600 & 1,000yds. My success’s are small and infrequent, and all I am saying is, 105 Hybrids shoot better in My barrels than 105 VLD’s. When I have had them, “Custom“ bullets shoot better than both of these.
The rest of the story. Through the end of last season, I was loading My 6BR with 30 grains of H4895. This load is “HOT”, as in “HOT”. Because of My inexperience, I didn’t know how hot. I experienced Case Head Separation on the 9th reload. After doing the research I should have done earlier, I learned loads like this are only good for 5 reloads, then accuracy is gone, and worse. I have now dropped back to 29grns, but I will not know the results until next weekend.
My conclusion is, or speculation, a marginally stable bullet in a 1 in 8 twist can stabilize when pushed to it’s upper safe velocity limit ?
But I yield to others to confirm or deny.
The rest of the story. Through the end of last season, I was loading My 6BR with 30 grains of H4895. This load is “HOT”, as in “HOT”. Because of My inexperience, I didn’t know how hot. I experienced Case Head Separation on the 9th reload. After doing the research I should have done earlier, I learned loads like this are only good for 5 reloads, then accuracy is gone, and worse. I have now dropped back to 29grns, but I will not know the results until next weekend.
My conclusion is, or speculation, a marginally stable bullet in a 1 in 8 twist can stabilize when pushed to it’s upper safe velocity limit ?
But I yield to others to confirm or deny.
VA_XTC_Shooter
Silver $$ Contributor
What is considered “hot” with Varget? I only tested 29.0-30.0. Granted I only shot 3-shot groups, but I do that as a quick recon, to identify the bad. Groups and ES won’t get better from 3 to 10-shot groups.
with that said, 29.0 and 30.0 performed the worst. At 30.0 I was
Pushing the 105s 2824 fps. But group was 1.80 moa with an ES of 39. Unacceptable. Notes attached.
The data with a / is data from Magnetospeed/Shotmarker. I don’t depend on SM data, it’s just another reference and to see correlations.
with that said, 29.0 and 30.0 performed the worst. At 30.0 I was
Pushing the 105s 2824 fps. But group was 1.80 moa with an ES of 39. Unacceptable. Notes attached.
The data with a / is data from Magnetospeed/Shotmarker. I don’t depend on SM data, it’s just another reference and to see correlations.
Attachments
Case separation is more a function of shifting the shoulders back excessively during resizing. Even reasonable loads will produce separation if your dies are set wrong.
The more telling symptom is primer pockets opening up to quickly fail to hold a primer
RegionRat
Gold $$ Contributor
The muzzle velocity does have some effect since the total RPM is a result of the twist at a speed, however in practical terms trying to get a bullet to stabilize with a hotter load is a risky method compared to just selecting the right twist for the bullet.
In some number of the marginal situations pushing the load hard has certainly worked for some folks, but in those situations I have seen a change in the weather or a trip to lower ground tip them back over too.
If you want to get a feel for this effect, play with that Berger web page and change the velocity and pressure. Then, just make a 0.5 change in the twist rate to see the change in stability factor. You can get your intuition tuned up with this software tool to help you get a seat of the pants feel without spending resources other than time.
ETA: If you wanted to spend a little more time, here is an article that leads to more information on twist and stability and what is really behind these numbers.
http://www.jbmballistics.com/ballistics/bibliography/articles/miller_stability_2.pdf
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VA_XTC_Shooter
Silver $$ Contributor
One other data point, I shot some of my 105 VLD loads that shot well in my previous barrel and those too didn’t shoot well.
I’m starting to wonder if it’s the barrel…
I’m starting to wonder if it’s the barrel…
These three examples are true when they take place. But, none of them happened in the experience I related. I purchased 400 pieces of New brass, and they will be loaded to a lower node.
Old Navy
Gold $$ Contributor
I think you need to check the twist. Possible you have a 1 in10.
VA_XTC_Shooter
Silver $$ Contributor
Good idea. Confirmed, 1:8
Check your systems. Either something is loose on the gun, the barrel is very poor quality, or some part of your reloading setup is not functioning. If your rifle cant get a 105 hyb to shoot well below moa out of a 1-8 6br with varget there is something wrong.
Take the rifle apart and reassemble to make sure everything is properly torqued and the barrel is floating free. Scope base and scope rings all tightened to spec and solid. Make sure your barrel is installed properly and you can't just spin it off with your hands. If you have a bore scope check to see if there is something obviously wrong in the bore. Check the consistency of your reloads. Use 2 different scales to verify powder charge. Check your brass for headspace variation and excess headspace. Make sure your setup produces consistent neck tension. I've seen something like this happening when some bullets end up touching the lands and some not at shot start. If you have enough neck tension to hold the bullet so you cant move it check each round for seating depth to insure consistency.
Once you are sure the rifle is assembled correctly and your reloads are consistent with charge and dimensions, if it still shoots poorly you either have bad powder, primers, bullets, or barrel. Try different powder, primer, and bullet. If that doesn't shoot its probably the barrel or you have undiagnosed Parkinson's or something.
And take off the magneto when shooting for groups. Use it to compare the velocity stats of loads that produced good groups.
Good luck trouble shooting. Keep us posted.
Take the rifle apart and reassemble to make sure everything is properly torqued and the barrel is floating free. Scope base and scope rings all tightened to spec and solid. Make sure your barrel is installed properly and you can't just spin it off with your hands. If you have a bore scope check to see if there is something obviously wrong in the bore. Check the consistency of your reloads. Use 2 different scales to verify powder charge. Check your brass for headspace variation and excess headspace. Make sure your setup produces consistent neck tension. I've seen something like this happening when some bullets end up touching the lands and some not at shot start. If you have enough neck tension to hold the bullet so you cant move it check each round for seating depth to insure consistency.
Once you are sure the rifle is assembled correctly and your reloads are consistent with charge and dimensions, if it still shoots poorly you either have bad powder, primers, bullets, or barrel. Try different powder, primer, and bullet. If that doesn't shoot its probably the barrel or you have undiagnosed Parkinson's or something.
And take off the magneto when shooting for groups. Use it to compare the velocity stats of loads that produced good groups.
Good luck trouble shooting. Keep us posted.
put on the old bbl and see if it still shoots---then change the scope--keep it simple---what distance are you testing at--you dont have to shoot at 600yds or a mile to see if thaings are good or bad--test at 100yds to save time-components-anxienty--if it wont shoot a bughole at 100 it wont shoot good on out --
Roger
Roger
VA_XTC_Shooter
Silver $$ Contributor
will check out the rifle and scope etc for anything obvious. I did scope the barrel and noticed these machining marks on the lands right at the end of the throat. Other than that, barrel looks good.
testing was at 100yds.
testing was at 100yds.
RegionRat
Gold $$ Contributor
Sometimes, chips and machine swarf will mark up the tops of those lands where the reamer pilot is trying to hold the tool centered on those surfaces, other times it is leftover from the drilling operation. I don't like to see it either, but I have seen much worse on bbls that perform just fine.
I'm never going to say never, but I'll risk an opinion that those surface finish defects are not extraordinary and won't cause what we have been discussing.
I'm never going to say never, but I'll risk an opinion that those surface finish defects are not extraordinary and won't cause what we have been discussing.
VA_XTC_Shooter
Silver $$ Contributor
Took it apart and reassembled. Scope mount and rings were solid. It is in an Eliseo chassis so nothing to keep it from free floating once it is tightened to the action. Used the recommended 50 ft lbs. Reloads were good, will use two scales on next set. But as mentioned, my previous good loads didn't shoot well either. Nothing during the teardown jumped out at me.
Will measure bullet to lands again to see if it is consistent and to verify loads were correct. All test loads were measured so they were at least the same length and same charge.
I did go back and look at load development on my last barrel and I did have some large groups with the AMAX and all of a sudden a charge shrunk the group. While no charge looked good with 0.015 off, I am still hopefully seating depth will get me where I need to be.
VA_XTC_Shooter
Silver $$ Contributor
That will be my next step after the next range trip.
I do all my initial testing at 100. Sometimes 200.
Liven The Dream
Gold $$ Contributor
Apples and Oranges 6 Dasher 105 HB on the lands a Hammer . 1-7.5 Varget 32.0 30" .
105 Berger VLD same load .025 jump good but not HB ?
105 Berger VLD same load .025 jump good but not HB ?
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