Group size at distance

[rsbhunter]

Not a new shooter, but still learn something new everyday, usually from this forum.....So , my question is....why do some guns shoot 1/2" at 100 yds and 2" @ 500 yds, and another that shoots 1/2" @100 won't hold 5" @ 500 yds ? I know in my case it's probably the loose nut behind the trigger, but curious if it's possible or for that to be a mechanical thing with barrel or load or?. Thanks for any info....rsbhunter

 

[Axl]

Can be a number of things from scope issues like parallax adjustment,
Bullet that isn't stable, mostly (in my case lol) it's the shooter!

 

[BW64]

The list is long. Best start with the nut!! LOL I usually start with checking for loose screws all around & set up. Then go to time between shots,loading specs etc.

BW

 

[Mram10us]

I have never built a rifle that groups well at 200 (that is where I initially test) that didn't shoot well at 500 or 1000. I still don't see mathematically how you can get good groups at one range and not the other. I'd have to see pictures

 

[WeiserBucks]

A load with high ES can shoot well at 100 and fall apart at longer distances.

 

[rsbhunter]

Mram10us, I agree...hence why I asked. I have one custom rifle that shoots under 1" @500 time and again....others that shoot good, but not like that....I understand about bullet stability, "going to sleep" at distance, importance of muzzle crown, etc...just curious if barrel harmonics, or whatever , exponentially increases as distance increases....obviously, with today's factory rifles, a lot shoot sub moa....which would translate to 1000 yd rifles capable of great accuracy....like I said, I'm not questioning gravity or the forces of nature, just curious...

 

[Mram10us]

A load with high ES can shoot well at 100 and fall apart at longer distances.

Have you experienced consistently small groups at 200ish with high es? I don't use my chrono enough is why I ask

 

[L.Sherm]

I believe vertical has alot to do with it, my Nephews 6.5x06AI that I put together would cut 1 hole at 100 but would shoot 4" groups at 500 with alot of vertical I changed primers and .5 m.o.a and 1" of vertical.
Theres a reason alot of BR guys I know final tune at 1,000 that they shoot

 

[WeiserBucks]

Have you experienced consistently small groups at 200ish with high es? I don't use my chrono enough is why I ask

I had a rifle years ago that would shoot about 1" at 200 and poorly at 600+ , after I got a chronograph I discovered that the load had an ES of 60 fps . Nowadays I don't even test for accuracy until I have a load that produces acceptable ES

 

[LongBomber]

Have you experienced consistently small groups at 200ish with high es? I don't use my chrono enough is why I ask

There can also be some positive compensation going on, a load with higher es leaving the barrel at the correct time in the vibrations could perform better at a certain distance than a low es leaving at a slightly different time. It is typically only possible to be more accurate at one fixed distance.

I have shot a few ladders at 300 that were sub moa for 14-15 shots, I would say that is fairly accurate for stepping up 100 or more fps in speed.

 

[milo-2]

I have never built a rifle that groups well at 200 (that is where I initially test) that didn't shoot well at 500 or 1000. I still don't see mathematically how you can get good groups at one range and not the other. I'd have to see pictures

Sorry, I have my fair share of loads shoot great at 500, but seem to unravel at 1K. The key for the op may be in shooting at 100 yards intervals and observe how and why the load falls apart, whether vertical and horizontal, or both. So, to the OP, if the rifle is an accurate one, 90% of the time it is the load, make some changes, one at a time. The further out you do load dev, the better chance of it holding goes up considerably.

I could type for 2 hours with examples, but one of my most perplexing ones was a brass brand switch on a 6 SLR. A few of us built them, all using junk Win orange bag brass, we all had hammer loads, hot and shot extremely well. We were ruining brass in 2 firings, yes that stupid. Local smith finds bulk Rem 243 brass at a distributor, oh boy, now let's switch. So I, do the math, case cap comparisons, blah blah, get close in theory, not much work, off and running, groups were under an inch at 500, bingo, big mistake not shooting it farther. On my next 3 outings, hitting plate from 700-1K is a crap shoot, now I am lost, finally group it at 1K, whoa, it is bad, 14-15" bad. Light bulb comes on, need a test between brass, so I did one, differing pressures on each brand, there was just no way the Rem brand was going to work once the standard had been set. Back to Win brand just to toast the barrel. This example is an extreme, which I know, but things can and do happen, and truthfully, I am not smart enough to figure it out.

 

[Plinker147]

Like others said high ES can cause this.

Also I find myself shooting better at 600yds than at 300yds. It's caused from simple lack of concentration. You assume the close group is easier so less concentration on basics. Wing nut behind the trigger!!

 

[Mram10us]

Sorry, I have my fair share of loads shoot great at 500, but seem to unravel at 1K. The key for the op may be in shooting at 100 yards intervals and observe how and why the load falls apart, whether vertical and horizontal, or both. So, to the OP, if the rifle is an accurate one, 90% of the time it is the load, make some changes, one at a time. The further out you do load dev, the better chance of it holding goes up considerably.

I could type for 2 hours with examples, but one of my most perplexing ones was a brass brand switch on a 6 SLR. A few of us built them, all using junk Win orange bag brass, we all had hammer loads, hot and shot extremely well. We were ruining brass in 2 firings, yes that stupid. Local smith finds bulk Rem 243 brass at a distributor, oh boy, now let's switch. So I, do the math, case cap comparisons, blah blah, get close in theory, not much work, off and running, groups were under an inch at 500, bingo, big mistake not shooting it farther. On my next 3 outings, hitting plate from 700-1K is a crap shoot, now I am lost, finally group it at 1K, whoa, it is bad, 14-15" bad. Light bulb comes on, need a test between brass, so I did one, differing pressures on each brand, there was just no way the Rem brand was going to work once the standard had been set. Back to Win brand just to toast the barrel. This example is an extreme, which I know, but things can and do happen, and truthfully, I am not smart enough to figure it out.

Mathematically, the 1" at 500 becoming 14-15" at 1000 doesn't make sense. I haven't experienced this. I do ladders at 500 then seating depth at 300 or 500. Maybe that helps. I'll play with this more with the chrono this week. Have some finalized loads at 300 and 500 that I'll take out to 1200. Thanks for taking the time to explain, guys.

 

[rsbhunter]

I agree, it seems that at a closer range (100) I almost concentrate too intensely on the reticle and bull, where at 500 and out, I accept the target picture and don't get "target panic". I appreciate all the input and help...rsbhunter