My .308 178gr. Hornady bthp load opened up...

[WoodchuckII]

After months of being out of 178 Hornady bthp's I finally got some in. I had worked up some promising data with the last boxes I had. I went out to test .1 increments around the load I had worked up (with the new bullets) and my groups went from sub M.O.A. to A.K.47 M.O.A. Same cases, same powder, same primers, same trim length, same o.a.l. I'm stumped. I sampled some bullet weights (10) low being 177.5 high being 178.3 average being 177.9. I'd get a decent group, then...flyer! Before my best groups were 4 in the same hole and one next to it. here is what I'm working with...
Savage 10 fcp sr
178 gr. Hornady match
Federal cases T.L. 2.008 (fired twice)
WLR primers
Varget (<>44 gr.) C.O.L. 2.803 (have not played with depth yet)

Any ideas on what tree to start barking up would be much appreciated.
Thanks in advance.
Ed

 

[gamestalker]

Considering it shot tight prior to this, I would be looking at my optics and my barrel. But it also isn't all that unusual for a different lot number bullet, to shoot different than another. I've experienced this before with Hornady and other brands as well.

Maybe the barrel is now touching the stock. Have you shot these loads side by side, with any of the previous loads that shot sub moa?

It's possible the glass went bad, or the rings or mounts might have loosened up.

GS

 

[FROGO207]

Also quite possible that the quality control of the bullets is not what it was with the last batch either as they are pushing things out as fast as they can. They might have changed the gliding metal composition. Or the barrel needs to be cleaned as stated above. These were my first thoughts.

 

[HexHead]

I don't find Hornady bullets to be as consistent as say Nosler.

 

[blarby]

Any possibility you had a bad day at the range ?

 

[USSR]

If a previous load with that bullet shot well and all of a sudden you are getting multi-MOA groups, then the first place to look is your bases, rings, and scope. Make sure the bases and rings are tight, and if so, then try a different, known to be good scope.

Don

 

[WoodchuckII]

Any possibility you had a bad day at the range ?

Thanks for the replies. I have work today, but I will be checking my base and rings later. @GS I didn't have the opportunity to shoot these loads side by side as I was unable to acquire these bullets for quite some time. Looking back through my previous data, it just doesn't match up. The rifle has been shooting factory ammo as well as another hand load as good as it ever has. @blarby, I was load testing so I was shooting from a lead sled. My previous data was compiled from a bipod in the prone position. The fact that my groups opened up shooting from a lead sled is even more disconcerting.

 

[dabuehl]

Hmmm. Lead sled.......

 

[WoodchuckII]

You have my attention....

 

[blarby]

Well, since Don has come up with another likely culprit for something so drastic, I'd check that first.

When my one accurate rifles' target holes start wandering, I do a little evaluation on my technique;

The first thing that pops up is the twice fired cases- perhaps the ones used in your last rounds had fireformed to help you (me) out a little ? This isn't a multiple MOA adding problem, just once more thing to make sure of when comparing benchrest loads to benchrest loads after a long absence.

Also, to get that sweet sweet one hole group, making sure your lot of powder is the same ( or a slight re-workup might be needed) as well as your primer lot and neck concentricity measurements in the new cases is going to be required.

I also weight sort both my cases, and my bullets.

But thats for losses in accuracy much less than you are getting.

AK47 MOA is usually not a result of some minor alteration of a known SUB MOA recipe, hence my first response. I hope it wasn't taken in a bad light.

Don nailed another very likely culprit.

I too, shoot precision from a bipod. If I used a new support method ( like a sled) That'd be something I'd look at- because all of the ones I've seen alter the way you handle the firearm, and that very well could be throwing you off. Sometimes small changes in posture, grip, or form can have very deleterious effects.

I don't know exactly which sled you have, so I can't quote specifics.... but prone on a bipod is certainly a different shooting posture than sled on a table, and that very well could have an effect. IS it certain, no, but if we're checking off boxes to get get to the answer, it can't be ruled out without some examination.

 

[WoodchuckII]

@blarby thanks for the input! Have not yet gotten back out. I will try from prone again as it is the only other thing besides the lot of bullets that have changed (that I know of). I'm working of the same 8lb. Jug of varget, same primers and as far as fire formed cases go, I full length size my cases as I was running into pressure issues with fire formed brass in the past. Never figured out why, but fl sizing remedied it. I did have a thread about that. Otherwise, the rings and base are tight. I'm going to load some more for this weekend. I guess it would be a good idea to pick up some factory loads for comparison.

 

[blarby]

Sounds like you might have some more answers after that run.

Otherwise, the rings and base are tight.

Having recently "shot the guts out" of my first scope, it physically can be tight as can be, and still not hold a zero.

Good luck, and let us know how it goes.

 

[WoodchuckII]

Well, got to the range yesterday. Shot from prone off my bipod, my group shrunk, not nearly enough though. I also brought some of my 165gr. interlock btsp loads out. This load shot ten shot groups at .8" at 100 yards. I think it's safe to say that the scope and rings are holding zero just fine. I should also note that I worked this this soft point load up to be good enough for deer. I'm going back out today, as I found some dummies with my original lot #of 178's, along with some 175 and 200 smk's. that I pulled. I'll let you all know how it goes.

 

[blarby]

Please do !

 

[WoodchuckII]

About to go out. Interesting enough...the new lot of bullets are .01" longer than the old ones. When I went to seat the older bullets with my die set for a col of 2.803 on the new lot, the col came out to 2.787 instead of 2.803. Which prompted some measuring. I think I'll be calling Hornady on monday.

 

[USSR]

Even with the best match bullets, a bullet's ogive will vary up to 0.01". This is why I never seat a bullet so that the ogive is less than 0.01" from the lands.

Don

 

[WoodchuckII]

Welp, new lot, shot about the same. Old ones, sub moa. Guess I'll just treat these like they're a completely different bullet.

 

[IMtheNRA]

Hi Woodchuck, I had a similar, though less dramatic problem last summer with Hornady bullets.

I loaded 100 rounds using a new box of Hornady .224 68-gr HPBT bullets and my group size increased by about 50%.

I used the RCBS Precision Mic and saw there is a significant difference in the new box of bullets and some of my old loads using the same bullets that I had purchased a year before.

I sent a sample of each to Hornady and they called me a few days later to say that I was right to suspect they had redesigned the bullet.

Same box, same part number, but a different bullet. A very frustrating experience since I had invested quite a bit of time and effort to develop a load my rifle likes.

Perhaps Hornady redesigned your bullet as well.