Same EXACT load as last years load shoots like crap

[jpfrog]

I may have missed how you made the changeover in powder and bullet. Your target picture notations indicate A4350 and 150 gr projectiles, and your original post states IMR 4350 and 168 Grain projectiles. Are you comparing apples and oranges?

The pictures you're referencing are from someone else, not the OP, showing their stock adjustments before and after. OP is using IMR4350 per original post. Something does feel like lot/component related though, I agree. Or perhaps something happened to the half full can of powder between last fall and present day to affect the burn rate?

 

[Philward]

Is the zero on your powder scale off, or was it off for the loads last year? Maybe it's not level or not zeroed correctly and throwing more or less powder than you thought.

 

[IHFarmer07]

I may have missed how you made the changeover in powder and bullet. Your target picture notations indicate A4350 and 150 gr projectiles, and your original post states IMR 4350 and 168 Grain projectiles. Are you comparing apples and oranges?

Two different posters……the OP is shooting 168 with IMR and a totally different poster posted group pictures with 150gr bullet and a4350.

Do confuse an already confusing problem

 

[skipglo]

Yes....it's about the most frustrating part of loading and shooting!!!! Just had it happen Thursday here. Here we wait 5-6 months for the weather to change and first outing.....a great big kick in the " squirrel food" to start it off....and for the next month you chase your tail trouble shooting...plllllllllllhhhhhhghh!

 

[Veteran]

Maybe his scale is way off.

 

[spladi]

Is your model 77 Ruger a wood stocked rifle? Maybe check for free float and tightness of the front action screw.

 

[Youngpatriot]

I am frustrated beyond expression. My 30-06 was a tack driver. Then it quit shooting well. Had it glass bedded, changed the load a bit, played with seating depth. Settled on an OK load which gets 1moa (it used to get 1/2 Moa). So I decided to load up all my empty cases and then test the load. First, I shot some of last September's load (this is now April). It shot well. So I loaded up several EXACTLY the same. Shooting 168 gr. Hornady BTHP over 59.3 grains of IMR 4350. (My old load was 59grains). This is a compressed load. The bullet seating depth, measuring cartridge base to ogive is exactly the same to .001. My cases are matched to within .004 of the same head stamp. This exact same load shoot 5" groups, all over the place. So, I shot 3 of my old loads. It shot a 1" group. So I went home, and very carefully loaded up more of the same EXACT load. It shot a crappy group. This does not follow the laws of physics and I cannot take this kind of weirdness lightly. BTW, each shot was put in the rifle individually and not in the mag, lest any chance of the seating depth being affected. Why is this happening?

A few things I can think of.
Barrel fouled up..unlikely
Your original lpads, were they in once shot brass, more, or brand new? This had made a difference for me in more than one occasion.
Something inside your gun has changed, example, a screw/bolt loosened. I've seen this is 700 ADL AND 700 BDL before.

My dad's 7mm (wood stock) and 338 (composit) both had same issue.

 

[jpfrog]

A few things I can think of.
Barrel fouled up..unlikely
Your original lpads, were they in once shot brass, more, or brand new? This had made a difference for me in more than one occasion.
Something inside your gun has changed, example, a screw/bolt loosened. I've seen this is 700 ADL AND 700 BDL before.

My dad's 7mm (wood stock) and 338 (composit) both had same issue.

Is your model 77 Ruger a wood stocked rifle? Maybe check for free float and tightness of the front action screw.

He already said it's not mechanical. The load from last fall shoots as expected in between strings of the new load on recent trip to the range.

 

[RUFFIAN R - NY]

Storage of powder between loadings, Different powder lots and or primer lots and bullet lots. Brass firings x2-x3-x4 ?? last time brass annealed ? and or trimmed .

 

[jpfrog]

I am frustrated beyond expression. My 30-06 was a tack driver. Then it quit shooting well. Had it glass bedded, changed the load a bit, played with seating depth. Settled on an OK load which gets 1moa (it used to get 1/2 Moa). So I decided to load up all my empty cases and then test the load. First, I shot some of last September's load (this is now April). It shot well. So I loaded up several EXACTLY the same. Shooting 168 gr. Hornady BTHP over 59.3 grains of IMR 4350. (My old load was 59grains). This is a compressed load. The bullet seating depth, measuring cartridge base to ogive is exactly the same to .001. My cases are matched to within .004 of the same head stamp. This exact same load shoot 5" groups, all over the place. So, I shot 3 of my old loads. It shot a 1" group. So I went home, and very carefully loaded up more of the same EXACT load. It shot a crappy group. This does not follow the laws of physics and I cannot take this kind of weirdness lightly. BTW, each shot was put in the rifle individually and not in the mag, lest any chance of the seating depth being affected. Why is this happening?

Some good suggestions this morning from @Philward and @Veteran - I'd be curious to see what happens if you try them. Basically, take your scale, zero it, then measure the powder from a round made last fall and then measure the powder from a round made recently to see if there's a difference.

 

[Hunterjones]

Pull the bullets and powder from last fall and load your stuff in that brass. Then load the bullets in your brass your currently loading, then use the powder from last fall. Start a process of elimination until you find the culprit.

 

[Frogman77]

Muzzle brake? Check to make sure it is tight.

If it's really your loads then something is not consistent. I've had wandering zero but really that can be attributed to many things. I've also had two or even three zeros possible just based on how hard you pull into your shoulder.

Consistency of shooter, loads and rifle all make a difference.

How many shots of the new load did you shoot? How many of the old?

Sometimes a small sample isn't fully representative of either.

 

[Hunterjones]

Man, this is a head scratcher. I've seen SIMILAR results on a couple of occasions with rifles that I never did figure out. I am retired recently from the precision machining business after 40 years so I know a bit about precision mechanics. I'm am with the poster who says to pull powder, primer, bullets out of old loads that shoot well and try in brass that does not shoot well……
Also maybe weigh a bunch of the old and new cartridge cases. I have seen 30'06 Hornady brass that varied 40 grains per cartridge case and everywhere between that has come out of same box of new brass.
Another thing I'd consider is throwing a set of 1" micrometers on bullets new and old and seeing if OD of newer loaded bullets are varying a considerably amount (.0005/one half thousandth) or more. I had a box of Nosler Accubonds a couple years ago that had the straight part of the shank tapered .0025 (two and a half thousandths).
Nosler replaced them for me. I would not have known they were tapered except that they were tapered big at boat tail and smaller toward ogive. When I started to seat them they felt fine and then once the boat tail got past the neck/shoulder junction they almost fell into the cases…..
It technically COULD be something mechanical but with the components not the rifle

 

[baggy270]

Folks, these are good thoughts but the OP has already stated that the rifle shoots tight groups with the old load in between strings with the new loads. In other words, if the OP weren't shooting with new loads and only using the old loads, it would be shooting perfectly fine as-is. Mechanical was where my brain went first, but based on his process, I don't see it applying here.

Exactly! Why don't people read whole post before commenting?