Inconsistent ballistics

Lawnboi

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Bumping this for a similar issue. I worked up a load and verified it with my standard practice- ensuring consistency between 3 distinct three round groups loaded on different occasions. The largest of these was 2/3MOA. Then shot a 100 yard group today with the exact same load, and the group was right around 2 MOA and center of the group had shifted probably 2 inches down. This is a Winchester Model 70 Extreme Weather SS wearing a Nightforce SHV in Warne rings that I personally lapped, checked the alignment on and assembled. 99% sure no screws are loose. Bullets are Barnes TTSX. Only modification between load development and today was removing the trigger to change the factory springs out for the Mcarbo spring kit. Ideas?
Did you torque the action to the same spec? When you put it back together?

Is the rifle bedded? Could you pulling the action and replacing have caused a shift?

Same lot of bullets?
Was the load made with virgin brass that is now on its second firing?
 

OXN939

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Something is loose, didn't get back together correctly, Pressure or not on Something new. Or something in the scope.
Nf is not impervious to damage and I believe the shv is a quality scope, but it is also there entry level.
Ammo just doesn't do that at 100 it would have to be wildy inconsistent.
You need to mount a good known scope.

Think this is the honest answer. Anyone got an ATACR they wanna loan me? Lolol
 

OXN939

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Did you torque the action to the same spec? When you put it back together?

Is the rifle bedded? Could you pulling the action and replacing have caused a shift?

Same lot of bullets?
Was the load made with virgin brass that is now on its second firing?

Same torque. Rifle bedded. Same box of bullets. All loads with 2x fired brass.
 

OXN939

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It mite inconvenience ya for a few weeks but im sure NF would check it out for ya.

Yeah. Gonna check a few more things before I send it on a field trip.

Powder is H4895, primers Federal 210M. No contraindication for using those with barnes TTSX that anyone knows of, is there?
 
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I would remove the scope, rings, bases and verify all screws are degreased and reinstall them all. Be sure to check the front screw of the front base to verify it’s not contacting the barrel threads and bottoming out.
Then load up another batch of test groups and head to the range.
 

huntnful

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I saw nobody mentioned how important the seating depth really is on your mono metal bullets. If they're seated a little too long (close to lands) they could potentially shoot TERRIBLE. I just had a proven load, shooting 3/8" groups with hammer bullets at 3.650 COAL. Loaded some up at 3.660 COAL (10 thousands too long) by accident and figured i'd just go test them out. They shot a 2" group at 100 yards. I came home the same day, reseated them at back to the correct 3.650 COAL and went right back out and was shooting 3/8" again. Not guaranteeing that's your problem, but it does really make a difference.
 

Flyjunky

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I didn't see it mentioned but how did you find your load? Were you using OCW development? How long have you been using this load?

I ask because one time we worked up a load for 212 Eldx's and it shot great. We were just messing around with this bullet/powder combo and didn't do a comprehensive OCW work up. The next time we shot this combo it wouldn't shoot for sh*t. Many times without a good OCW development you'll think you've found a good combo but the combination you found only shoots good one time.

I probably didn't explain that well but if you want more info I can send you a link to a very good video on OCW that explains this phenomenon.
 

OXN939

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I saw nobody mentioned how important the seating depth really is on your mono metal bullets. If they're seated a little too long (close to lands) they could potentially shoot TERRIBLE. I just had a proven load, shooting 3/8" groups with hammer bullets at 3.650 COAL. Loaded some up at 3.660 COAL (10 thousands too long) by accident and figured i'd just go test them out. They shot a 2" group at 100 yards. I came home the same day, reseated them at back to the correct 3.650 COAL and went right back out and was shooting 3/8" again. Not guaranteeing that's your problem, but it does really make a difference.

Interesting that such a small difference would change thing so drastically, especially with Hammers. Using COAL as a loading metric, it's actually tough to get much more accurate than plus or minus three thousandths, since the plastic tips of TTSXs can vary by length that much. Do suppose the most consistent way of all would be just to leave your dies set once you find a good load.

I'll just run pick up an extra seating die real quick 😂
 
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Interesting that such a small difference would change thing so drastically, especially with Hammers. Using COAL as a loading metric, it's actually tough to get much more accurate than plus or minus three thousandths, since the plastic tips of TTSXs can vary by length that much. Do suppose the most consistent way of all would be just to leave your dies set once you find a good load.

I'll just run pick up an extra seating die real quick 😂
Or you can buy a comparator and measure off the Ogive for more consistency.
What dies are you using?
 

huntnful

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Interesting that such a small difference would change thing so drastically, especially with Hammers. Using COAL as a loading metric, it's actually tough to get much more accurate than plus or minus three thousandths, since the plastic tips of TTSXs can vary by length that much. Do suppose the most consistent way of all would be just to leave your dies set once you find a good load.

I'll just run pick up an extra seating die real quick 😂
Yeah dude. I’d bet I could seat them deeper with good results, just judging from what I read, but they definitely did not like being that close to the lands. The hammers are all machined and dang near exact on the COAL measurements. But I know what you mean about the plastic tip. Do you have the bullet comparator gauge for your micrometer? It’ll give a pretty precise number to verify each load with.
 

OXN939

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I didn't see it mentioned but how did you find your load? Were you using OCW development? How long have you been using this load?

I ask because one time we worked up a load for 212 Eldx's and it shot great. We were just messing around with this bullet/powder combo and didn't do a comprehensive OCW work up. The next time we shot this combo it wouldn't shoot for sh*t. Many times without a good OCW development you'll think you've found a good combo but the combination you found only shoots good one time.

I probably didn't explain that well but if you want more info I can send you a link to a very good video on OCW that explains this phenomenon.

I didn't use that process, but it looks interesting. Basically I verified my load three times with 3 shot groups. So, it's definitely not the scenario where someone sees one tiny group that's a statistical outlier, gets really excited and then can't reproduce it.

Or you can buy a comparator and measure off the Ogive for more consistency.
What dies are you using?

Using these. I really should invest in one of those comparator gauges at some point I guess, but I don't think it's likely that being 2 or 3 thousandths off would make the average size of a group increase by 400%.


And, truly, if a load requires that gnat's ass level of precision to get even mediocre performance, it's probably not one most recreational reloaders should be interested in anyway.
 
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