Switching bullets effecting zero?

[T3ninja]

I used the search but didn't see what I was looking for.

So just a quick background followed by simple Q.

Rifle- .300 win 28" proof in XLR chassis Meopta optika6 <—- has performed flawless and I have no reason to think the scope is on the fritz.

2 loads ... 215 Berger and 190 Nosler CC. Both loaded with Ramshot magnum.. rifle is zeroed at 100 with the 215's

So I get to the range and first shot of the day is at 600 yards and it is perfect! So I follow with 2 more perfect shots at 1k! I am EXTREMELY happy. I put the rifle away and plink with the .308 for a bit. Pull it back out and start to burn up my 190 noslers (8-10 shots in about 35 min)

After letting everything cool off and re painting targets I wanted to finish the night off with the 215's. 800 yards... boom, Nothing. Sent another, nothing ???? After the 3rd shot I found the round hitting .4 mil low. With only one round left I shot again and it hit .2 low... out of ammo and range is closing so no more testing...


So the Q is, has anyone noticed a big change in impact from switching bullets? I never changed my zero. I keep my zero set for the Berger's and used the noslers just as trigger time. My ES/SD is very good (under 10), weather conditions were essentially the same, and I had a kestrel with me.

Thanks in advance !!

 

[imyourhuckleberry]

It is bound to happen if the BC or weight changes. According to the harmonics in your barrel the bullet may not exit at the same point from your barrel or the drag coefficient will alter the flight path differently than the other bullet you switched from.

 

[WildBillG]

Is there any chance you used the 190 data when you switched back to the 215's.

 

[Country Bumpkin]

Are there different qualities of the copper material between the two different bullet brands that are leaving more or less residue in the barrel (affecting velocity)?

 

[T3ninja]

I'm your huckleberry: I'm comparing impacts only from the 215 Berger, they were spot on for the first 3 shots. Then I shot up some 190 noslers, just for getting my brass back (adg) then switched back to the bergers.

Wildbill: I actually never pulled out the data for the 190's, But I did double check that.

Country: This is what I'm referring to, I'm wondering if anyone else has seen this. Im sure there are, Nosler/Berger. I've heard of different powder causing something like this, but it's all the same powder/lot from an 8 lb jug . I'm going to go again next week and see if I can mimic these results.

 

[Hatrick]

I am with Country on this. I think many people on here will advise to decopper before switching bullet manufacturers.

 

[cohunt]

Not to be harsh-- you are shooting at 800-1000 yards and not only dont realize but expect both 190 nosler and 215 bergers to hit the same spot without adjusting your scope zero? Something seems amiss, or I'm misunderstanding

 

[Laelkhunter]

To answer your question, YES I have noticed a big change in point of impact when switching bullets. Bullets of the same weight but different bullet makers will give a different point of impact, and bullets from the same bullet maker but a different weight will be a different point of impact. At close range, even 100 yards the change is noticeable, so at 800-1000 yards, the difference could be really noticeable (like more misses than hits).

 

[thatguyshm]

I think I'm understanding what you are asking. You don't expect both bullets to hold the same zero. Your problem is you fired the 190s after success with your 215s, then after the 190s your original zero was off for your 215s.

If you were impacting high i would say more pressure due to copper build up, hitting low though is a bit of a mystery. How many rounds of 190? What powder? Did it have a decoppering additive? How does the 215 impact on a clean barrel? I would say try again, use a chrono so to figure out if velocity changed?

 

[T3ninja]

I think we're getting somewhere but, yes some are mis understanding. I am not trying to get both to hit in the same place.... I actually don't care at all where the 190's land. They are an older load that is sitting in brass that I want to load up. So I'm just shooting them. I know they shoot different than the 215's. As a matter of fact the 190's are running almost 200 FPS faster. Basically the bergers shot different from before to after shooting the Nosler.

 

[codyadams]

PEOPLE!!!!!

I think most of you are missing what he is saying, re-read. He is zeroed for 215's. Shot 3 rounds of the 215's, making good impacts. Then shot some nosler 190's WITHOUT CHANGING HIS ZERO or anything else on the scope. Then went back to the 215's, and they were hitting low. Same powder in the two loads, same brass, very possibly even same primer, just different bullet. The ONLY variable here is the shots between the first and second shooting session using the 215's. So that leaves only a couple possibilities, either the copper left in the barrel from the noslers changing his POI with the 215's, or in between there, the scope/mount had an issue (very possibly started to come loose towards the end of the 190's shooting session, double check mounts....)

Again, this is NOT comparing the POI between the 215's and the 190's, it is comparing the impact of ONLY the 215's before and after only shooting 190 nosler cc's, without changing ANYTHING on the scope.

Carry on!

 

[T3ninja]

Thatguyshm.... nailed it. Same powder. Ramshot magnum. Both loads(bullets) were loaded with same brass, and powder lot (different charge).


So would copper Fouling from Nosler cause Berger to be off this much?. .4mil at 800 is roughly 1 foot.
Like I said in original post it seemed like they were moving back up to where they were supposed to be, almost like I was fouling a clean barrel. I understand so many things can be happening, but this thing has shot so well with both loads, but I've never switched back and forth during an outing or without cleaning. Btw this rifle (out to 460 yards ) shoots within .1 or POA with a clean/cold barrel as a fouled barrel, and these were shots 11-25 or so after a good cleaning.

 

[T3ninja]

Cody nailed it. Ring mounts are good. I did not pull them to check the rail, but it's lock tite down and it's got some big screws #10 maybe ? It's an ARC nucleus . I'm pretty certain they are tight.


Edit: yes same primers fed Lr magnum

 

[codyadams]

This is assuming that the rifle was a proven, squared away rifle prior to this happening.

First thing, check that all rifle and optic fasteners are secure. This can head off some tail chasing. Then load up ammo and shoot at 100 to confirm zero. This will tell you if that changed, only cost 3-5 rounds, and accuracy will give you an idea where to go from there. Good accuracy, but .4 MIL low, POI change, log that in your mental notebook, and re-zero, shoot some steel for fun to confirm drops are still good. Crappy accuracy.....many things possible, start with the basics. I have heard of issues arising from switching bullets, but the results were often varied from excessive copper fouling, carbon ring, rifle action screws coming loose, scope mount screws coming loose, scopes (even high end, $2000+ optics) breaking, and so on. For bad accuracy on a once proven rifle, this is roughly the route I would take, depending upon scenario -

A -
If some fasteners were loose, torque them properly, possibly with blue lock tight depending on application, then check 100 yard accuracy/zero, and re-zero and carry on if accuracy is good. If accuracy is bad, move to next step.

B -
If all the rifle and optic fasteners never came loose, and accuracy suffered, that narrows it down. Either something in the bore, or something in the optic. I would switch optic with a known good one first, simply out of curiosity, I would want to know if the different jackets caused the issue. If accuracy is good, it was the optic, go from there on warranty, etc. Still bad, that leaves the barrel. Clean the bore down to bare metal, test for accuracy again. Still poor accuracy after cleaning bore and giving proper fouling rounds with a proven optic, put the optic back on your other gun and check to make sure something didn't happen while on the other gun. I have seen one specific gun that liked to kill scopes, a Ruger mini 14. I know that isn't the case here, but if mounts aren't right they could cause issues, so it is always good to double check when trouble shooting to rule any possibilities out.

At this point, everything has been checked and double checked on a once good shooting rifle, all seems well accept accuracy, if you have a bore scope you can check tha out, see if possibly voids in the rifling from faulty steel arose and began causing issues, or have your smith do it. Though rare, this has happened even with high end (Krieger, Brux, Bartlien, Proof, etc.) barrels, they simply get a round of steel that has voids that didn't appear in manufacturing, but after some rounds down the tube they came up. If you don't have a bore scope, take it to a smith to be inspected. If this is the case, as long as the bore hasn't been nitrided or some other chemical treatment done, Proof will more than likely replace the barrel for you after you send it in to them, free of charge. You will still have to pay your smith to install it.

Hope this helps, just report back whatever you find, would like to hear the resolution. Hopefully it's a simple one!!!!