What could cause group outliers?

[SuperBruce]

I have what seems like a good load developed using 178 ELDM bullets with TS 15.5 in Lapua brass but I'm experiencing odd fliers. SD is ~10 fps over a large number of loads and velocity is averaging 2590 fps. On average, out of 4 shot groups (odd number but it's how many my internal mag holds so thats usually what I do with this rifle) I'll have 3 making up a 2/3 MOA (or less) group and the other shot is 1.5 to 2 inches away. Sometimes this is 2 of 4 touching, sometimes is just a good group for all 4 shots. This rifle will generally shoot just under 1 MOA groups with a good load: no match rifle but fliers are not the norm. However, it is a bit picky of a barrel: not all projectiles shoot well in it.

I'm inclined to chock it up to one (or more) of a the following causes:

1. These are pandemic projectiles so perhaps I may have a not-so-good batch.
2. My jump maybe in a sensitive spot (only tried one jump so far), although I do check the CBTO on all rounds and they're quite consistant showing a variance of about 1 to 1.5 thousandths.
3. These are just not a good bullet for this picky barrel.

I'm interested to know what more experienced people think. Thanks in advance.

 

[Rich Coyle]

Perhaps that's the size of your group if you fired a ten shot group. Maybe you could try another primer.

Primer is the last thing I change to nail down a load. I always start with the Federal 215 Magnum primer so I don't have to change powder charge when I change primers. In your case I would fire four with as many primers as I have. If two holes are not close I would not fire anymore of that primer. I have seen out of a group of six primers, one is half the size of the others. I redo all that are promising to verify the results.

 

[Rick Richard]

Play with #2 to rule that out.

 

[Dmagna]

Probably seating depth, if you have low SD adjust seating and if it doesn't tighten the groups then throw out the bullet

 

[eoperator]

Listen to the Hornady podcast "your groups are to small" series. You will never look at small groups the same again.

 

[K.E.C. Darkside]

When this happened, was it 1 day at the range or over multiple different times out. Sometimes I might be the problem, not having a good day behind the trigger. And how long have you used TS 15.5

 

[Iketurner]

Definitely would love to hear what actually fixes the issue, in case I experience this problem

 

[SuperBruce]

Perhaps that's the size of your group if you fired a ten shot group. Maybe you could try another primer.

Primer is the last thing I change to nail down a load. I always start with the Federal 215 Magnum primer so I don't have to change powder charge when I change primers. In your case I would fire four with as many primers as I have. If two holes are not close I would not fire anymore of that primer. I have seen out of a group of six primers, one is half the size of the others. I redo all that are promising to verify the results.

It's the size of my groups if I fire 4 shot groups. Joking aside, it's a pretty consistent pattern of a tight cluster and 1 much further out (I've shot maybe 8 groups like this so far, I loaded up a bunch of these). However, I'll admit it certainly could be the intrinsic group size for this rifle with this load and I'm just talking myself into it being "something" I can easily fix.

I have been using CCI-200's but I do have some federal 210's I could give a go. Doesn't hurt to try.

When this happened, was it 1 day at the range or over multiple different times out. Sometimes I might be the problem, not having a good day behind the trigger. And how long have you used TS 15.5

I've been using TS 15.5 for a while but until recently only in 6-dasher, and even there it's been mostly on standby as I have a really good load with another powder. I tried it out in my 308 after reading this article here where they tested TS 15.5 with the 178 ELD-X. Velocities are great (this is a 18" rifle and I could push a good bit faster but the groups open up) and the groups are about as good as I've gotten from this gun, other than the fliers.

Play with #2 to rule that out.

Seems like a number of folks thing #2, and it's not #2, it's either #1 or #3. I'll give this a try.

 

[Chadp82]

I am assuming you are at 100yds? If so, and it were me, I would go to 200 or 300 and see what it does before chasing it at 100.

 

[Tiny Tim]

Is the flyer random in the shot string or is it the same in each, i.e. First, last, other?

 

[BillLarson]

In a hunting gun.... don't let barrel get warm.....
I shoot the same target 2-5 days in a row.
1 shot... only
With dirty barrel.....

 

[L.Sherm]

What brass?

 

[JiminAZ]

I had this phenomenon once in a 308 and getting the jump right solved it. Improvement was dramatic. In my case it was SMK 168s and IMR 4064.

 

[Prairie Sasquatch]

I've got a stock Savage 111 25-06 that will shoot .5 MOA with first three shots. Anything after those first three and the sporter barrel gets hot and groups open up to at least 1 MOA.

Its current diet is mostly 115 Bergers but it will do it with a 100 grain TTSX load too. Same thing with 100 grain Sierra Game Kings I used to shoot.

For deer hunting and the occasional coyote it's no big deal.