Load going from hot-to-not: what happened?

[hardlyworking]

New barrel/rifle/case/bullets to me and I worked up a load ladder with three round groups. I know this is not optimal, but with a brand-new-to-me everything seemed prudent for a first load workup.

Rifle was shot off the bench, with a bipod and my rear-fist. Again not ideal, I know, but its what I had.

My best group put all three holes in the same 1" paster at 100 yards, and was middle-of-the-road for the charge so I was feeling pretty good.

My next goal was to do a seating depth test, so I picked the load that shot well, and did 5-round groups at the same COAL, 0.1 shorter, as well as 0.1 and 0.2 longer. 0.2 longer is just about MAX magazine length for magpul AICS pattern internal dimentions.

Went back to the range and this time I laid down prone behind the rifle and shot my 5-round groups. The previously best group shot like crap, and the best group of the 4 seating depths was apx 1.5 inches at 100 yards.

Can changing bench/sitting to prone (both on concrete) cause THAT much variation? Should I re-work my whole charge weight ladder now if this is going to be a prone-rifle? Or was it just that my 3-round group which I thought was awesome really wasn't and the crap statistics of a 3-round group bit me in the butt?

Quite possibly lots of factors played a part in the poor groups. I would be reassured if some of you experienced reloaders have seen dramatic shifts in group size going from different shooting positions. But if not, I can chalk it up to those other factors and need to address those first.

[pennstater]

I would get a rear bag and a front bag as well. That bipod is doing you no favors developing loads and learning the new rifle. Especially on cement.Not good. Too much "bouncing" if you will. Go back to your first load, but, get bags or some form of more comfortable rests. If you get bags, fill them with new cat litter. More pliable that way. Optics?

[kcstott]

No mention of bullets used, nor caliber, barrel length or profile, the more information you give the better response we can provide.

aside from my experience in recoil profile that i'll get to in a second. No mention of the bullet makes me wonder if the jump is causing you issues.
in load development you need to start at .020" off the lands or there abouts. it's a good safe starting point. then work forward not back.
Mag length?? yeah good luck with VLD's if thats what you're using, I've only found a few bullet profiles that are jump tolerant.

I think the "New" cat litter goes without saying

I any event what you are experiencing is differences in recoil profile. This can shift POI inches and open groups up.

I know if i don't load the bipod on my rifle the grouping opens from .5 to about 1"-1.5" and shifts upward. this is of minor frustration at 100 yards but at 1000 this costs me points

[Scottie15]

Reduce the variables when looking to compare loads shot one day to the next. Shoot of the bench or bags, or bipod, just be consistent. Shooting prone off a bipod changes your natural point of aim, how your body lines up with the stock and how you handle the recoil of the shot.

Also, varying your length by 0.1" is A LOT!!! Not sure if that was a typo, but try different depth variations with 0.010" or 0.020" intervals. For lead bullets, I usually do what kcstott said - start 0.020" off the lands and move in and out from there. If shooting copper bullets (Barnes), start 0.050" off.

[highpower790]

Check the lot numbers on powder containers!Did you finish one container and move on to another.Lot numbers might not be the same.

[jimmykan]

Was there a major difference in ambient temperature between last time and this time?

Some powders exhibit up to 2 fps change in muzzle velocity per degree Fahrenheit.

[Gunsrruss]

Car Mat...if like carpit

Use your rear car mat to put that Bi-pod on. It can improve your shots by eliminating vibration. Also your spot-well will change from one position to the other.

[Metal God]

I agree more info is needed but as others have pointed out . Changing that many variables will almost always change the results . Three shot groups are not the best way to go , again it's not uncommon a good 3 shot group will only be an ok 5 shot group . A ten shot group will Be even worst . Remember your group size will only get larger the more shots you take , they can't get smaller .

I personally shoot 5shot groups in load development and 10 shot groups to. confirm a load is good . FWIW my 10 shot groups are alwwys slightly larger then my 5 shot groups .

[Witch Hunter]

Start over with your best load and adjust seating depth in .002 increments. At your increment rate you will jump over accuracy nodes without knowing it.

[kcstott]

.002" is for final fine tuning. .010" to get you close then .005" then .002"
But with the inconsistency in bullet ogive. Precision of dies slip in the press .002" is over kill.

If your bullet seater is hitting a 10 degree tangent point on the ogive, then a .0005" change in diameter equals about .003" in overal length. So seating in .002" steps is futile

[jimmykan]

If I experimented with 0.002" seating depth increments only, I might need a new barrel by the time I found the optimal seating depth.

Berger bullets put out an article that suggested an increment of 0.030" to 0.040" for your first test. The author was talking about VLD (secant ogive) style bullets, but it could apply to hybrid and tangent ogive bullets too.


http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/

[hardlyworking]

Single dad this week, so I apologize for not getting back to this sooner!

Rem 700, Criterion Pre-Fit (Remmage) Heavy-Varmint target crown (no brake), 6.5 Creedmoor. Lapua brass, Berger 140 Hybrids. SWFA 3-15x scope. XLR Element chassis. Scope rings, mount, stock mounting screws, and barrel nut all checked for tightness (confirmed: nothing moved)

I have only put 50 rounds through the barrel thus far, so that may play at least some part in this also.

Thank you to everyone for the suggestions thus far. It sounds like I indeed need to start over on my load development from the position, base (dirt/concrete, shooting mat/bare earth) that I intend to use, and do my load workups there. Along with getting whatever sand/litter bags I will eventually use, get them now, use them for load workups.

For some applications it may not matter much if your groups open up +1-MOA from when you develop them to when you use them (hunting/SD within 200 yards) but I am going for much better than that with this setup.

One other note, is that my brass I am loading right out of the box. There is a perfectly consistent 0.001 change in the size of new/unfired vs fired cases using the hornady case comparitor / datum line tool.

Am I going to have to go through all of this again once I start using once-fired (neck sized) cases? Should I just buy some cheap V-max 6.5s and finish "fire-forming" my next 50 cases so they can all be resized before starting down this road?

[kcstott]

Single dad this week, so I apologize for not getting back to this sooner!

Rem 700, Criterion Pre-Fit (Remmage) Heavy-Varmint target crown (no brake), 6.5 Creedmoor. Lapua brass, Berger 140 Hybrids. SWFA 3-15x scope. XLR Element chassis. Scope rings, mount, stock mounting screws, and barrel nut all checked for tightness (confirmed: nothing moved)

I have only put 50 rounds through the barrel thus far, so that may play at least some part in this also.

Thank you to everyone for the suggestions thus far. It sounds like I indeed need to start over on my load development from the position, base (dirt/concrete, shooting mat/bare earth) that I intend to use, and do my load workups there. Along with getting whatever sand/litter bags I will eventually use, get them now, use them for load workups.

For some applications it may not matter much if your groups open up +1-MOA from when you develop them to when you use them (hunting/SD within 200 yards) but I am going for much better than that with this setup.

One other note, is that my brass I am loading right out of the box. There is a perfectly consistent 0.001 change in the size of new/unfired vs fired cases using the hornady case comparitor / datum line tool.

Am I going to have to go through all of this again once I start using once-fired (neck sized) cases? Should I just buy some cheap V-max 6.5s and finish "fire-forming" my next 50 cases so they can all be resized before starting down this road?

I full length size my brass for F class long range, Zero issues.
You need a chrono, and 30 rounds loaded, load 10 rounds in steps of .2gr steps from min to max one round per step, bullets seated .020" off the lands. Shoot these for velocity reading only, we don't give a damn where they hit on the paper.
Find your velocity plateaus, you will find at least two velocities that level out even though you increase the load three to four steps, load five rounds centered on that velocity plateau and shoot for a group, Then approach the land .005" at a time load five rounds at .015", .010", .005". shoot those for group.

you should have a solid load after 30 rounds fired. No need to waste ammo and over think this crap. you're not shooting bench rest.

I've used this technique many times and my rifles shoot .5 MOA groups or smaller and I can select a new bullet and work up loads in 30 rounds or less. I don't have the time nor the money to run back and forth to the range to check every little nuance of the load. Again we are not shooting bench rest. if you can shoot five rounds through the same hole why do you care?

Rifles I've done this with

.220 swift
7x57
multiple .308's
.300 win mag
.408 Cheytac
Every rifle produced a solid accurate load with low ES and SD