2 in, 1 out question.

[ksubuck]

Had a question about the old theory of adjusting seating depth to bring the flier back in to the group. I almost always hear people suggest seating the bullet deeper into the case in 0.005 inch increments to see if you can bring it in. I have had mixed results doing this. I have also heard people suggest a tenth or two more powder to draw the shot in. Also have had mixed results here as well. What is the theory that leads to that one flier? How do tiny adjustments fix it?

I currently have a load that I think reaching closer to the lands might find my sweet spot. Anyone find that it helps to increase OAL in the face of a 2 in 1 out grouping? My 325 WSM is shooting 2 shot bugholes very frequently but never 3 shots...

 

[ElmerThud]

This one has always been a difficult question. Personally I think it's about where the muzzle is at the point of bullet exit. In other words barrel harmonics. It goes without saying the more consistent your loads are, the better chance you have of creating a more level playing field for each round fired.
But, not all brass is equal - even from the same lot. Variations in brass may be very small, but nevertheless affects the case performance. So even if you make the best possible effort with your reloads and neck tension, the chances are that you'll still have flyers.
Often the flyer will be the second shot, with the third shot re-aligning with the first shot....but, not always.
For hunting purposes the flyer is not usually a real issue unless it's significantly distant (which normally it's not). But for target/benchrest shooting a real frustration.

My own findings have led me to stay with the load demonstrating the best accuracy, then fire off rounds giving an extended period of cooling time between shots.
Invariably there were fewer flyers. i.e. the two in & one out (almost) disappeared.
It's a ball ache waiting for the barrel to settle between shots though!

 

[Dwh7271]

Anyone find that it helps to increase OAL in the face of a 2 in 1 out grouping?

In a word, yes.
My 260 AI was doing two and one. Shortened, no joy.
I started lengthening and it kept tightening. I was at COAL of 2.75". The load is finished at 2.88"
If it matters, it's 48.3 H4831 in fireformed Nosler brass, 210M primer, 140 AB.Speed is right at 2920.
I did have it throated a little long to seat the bullets out a little. Didn't really plan on quite that far but it works.

 

[Guy Miner]

A very experienced handloader, cartridge developer and rifle builder, Doug Arnold, told me that when handloading, he believed that the seating depth & relationship of the bullet to the lands & grooves was more important than the powder charge, for accuracy.

This was contrary to what I'd believed for many years. I had to do some thinking.

Anymore, I believe he's got an excellent point, and pay a lot more attention to seeking the proper bullet seating depth. This is something I hadn't played with a lot, because most of my "accuracy loading" was done for a short-action .308 Win, with the chamber specifically cut for 168 gr Federal match ammo - so if my handloads essentially replicated that factory ammo - I was good to go. My overall cartridge length was pre-dictated by the length of the magazine and my desire to match the factory ammo, so I'd had no real need to play with seating depth much, and used powder charge variations to bring in the best accuracy. That, and the heavy-barrel .308 was just eager to please anyway. It groups most ammo I shoot through it rather well.

But ol' Doug Arnold (founder of Arnold Arms, a builder of very fine rifles here in the Pacific Northwest) woke me up a bit with his insistence that cartridge length/seating depth was so important. I've used his advice to help improve my .25-06 loads, and that rifle shoots very well for a factory barreled sporter.

Long-winded way of saying - sure, mess with the seating depth!

FWIW, Guy

 

[hubcap]

Agree with you Guy. The only thing I could add is that is on occasion I ended up changing to a different powder. Sometimes that can cure all evils. Now if I could find a cure for my trigger finger not working correctly every shot. All would be well.

 

[Wyo7200]

This might interest and lend info to the argument of seating depth. Next go around I am going to seat my bullets closer to the lands and see if the groups shrink.

http://www.the-long-family.com/bullet_dispersions.htm

 

[Guy Miner]

Agree with you Guy. The only thing I could add is that is on occasion I ended up changing to a different powder. Sometimes that can cure all evils. Now if I could find a cure for my trigger finger not working correctly every shot. All would be well.

Yeah. Agree. Normally when my rifle isn't shooting well... The rifle and ammo are just fine - it's the nut behind the trigger that needs an adjustment... :mrgreen:

 

[Ridgerunner665]

How do tiny adjustments fix it?

...

The tiny changes change the barrel time...

 

[shoots_5]

I've had pretty good luck lately with picking a powder that gives good load density and a charge that gives me the velocity I desire and then tuning seating depth to tighten up groups. A little unconventional way of doing it but it has worked pretty well and saved time and components in my load development. If I can't get the accuracy I desire doing that then I'll look at a different powder or try changing charge weight.


Sent from my iPhone using Tapatalk

 

[longrangehunter]

I usually find the COAL to the lands and back it off by 0.010"-.0175". That number may seem weird but it's very hard to actually be that accurate in the distance from the lands with each bullet used. (They all measure close even off the ogive length but are not all the same and that's why).

Most calibers will benefit from being closer to the lands, as long as you can reach them through the magazine box. If not test another bullet maybe for a better seating depth that does work through the magazine box. The barrel will either like the bullet or not IMO, and yes the seating depth is very important for maximum accuracy, but some guns just won't shoot really small groups either because how they were put together.

Pick a bullet, work off the lands, test the powder for low ES, and SD, last maybe change the primer if close.

 

[ksubuck]

I walked the seating depth out towards the lands in 0.005 inch increments. The first two groups were 2 in 1 out, the third group stacked 3 shots in a vertical group, the fourth gave me a nice 0.4 MOA clover leaf, and the fifth group was 2 in one hole 1 almost in for a 0.5 MOA.

Turns out the best group is running 0.050 off the lands. Will load a few more and reverify. Think I finally have the load where I want it. Will have to carve a small amount of material out of the magazine to give the round a little more room, the bullet tip just slides in to the mag at this length.

 

[Guy Miner]

Looks like you've found it!

 

[DrMike]

That is looking mighty good from this vantage point.

 

[hubcap]

Wow, you did good solving that 2 in 1 out mystery.

 

[Darkhorse]

No matter whether you creep in or out your still chasing that sweet spot. I think there are several and when you pass one you can still catch the next one. I keep my targets so I can keep track of the results.

 

[OU812]

Looks like you found the node alright, good shooting.

 

[Darkhorse]

If you notice, the first target I was seating closer to the rifling each shot and found a sweet spot while doing so.
The second target I had already tried seating closer to the lands with no luck, but when I seated deeper I found a sweet spot there also.
I think the barrel oscillates in a repeatable pattern and regardless of whether your just off the lands or .050 and more away that sweet spot can still be found by analyzing your targets.
I bedded this 35 year old rifle and did some trigger work. Other than that this is how the rifle came from the factory. I have a few loads that print under or right above 1/2 inch.
I think that's pretty good for a factory rifle.
Of course your rounds must be as concentric as possible to the axis of the bore. This allows your rifle to really shoot to it's potential.
These were all shot with 63 year old eyes and a 10X scope. Really hard to see. Wish I had a 20X.

 

[DrMike]

Pretty dramatic illustration of the impact of seating depth on a load. Thanks for posting.

 

[Kodiak]

I've always liked 0.020 and worked out from there if needed. Many cartridges, depending on bullet-nose shape, liked 0.040-50. Had one rifle that somebody had long-throated and there was no way to get a round that close and still push them down in the magazine.

Jim