I have a 270 win that im loading 135gn SMK's behind 58.5 grains of h-4831sc. I dont get too much time at the range during the summer months but ive went 5 or 6 times this month and i consistenly get 1-inch groups with this load.but the other day i moved it out to about 285 yds and my 4 shot group was about 5 inches!
and i had a steady benchrest so i know it wasnt moving so whats happening here??

thanks

Two things, at least.

First, your 1" group at 100 yards will be around 3" at 285 yards.

Secondly, no matter how steady the bench, you ability to hold on the exact same spot on the target at 300 yards is limited.

And finally, even a 5 MPH breeze will have a much greater effect at 300 yards than it had at 100.

blake

If you're getting 1 inch groups at 100 yards your 285 yard groups will probably run 3 to 4 inches at best. It's not a straight line increase in group size as the distance increases. But a more likely answer is that you are not reading conditions. Do you use wind flags?

Your not wrong, and if you have enough wind flags, some will get into an arguement on just which way the wind is (or isn't) blowing.
JL

quote:

It's not a straight line increase in group size as the distance increases. But a more likely answer is that you are not reading conditions.

A fact not taken into account by too many hunters!

Mirage and shifting and/or variable wind can play real havoc with your long range groups.

Regards,
hm

And Parallax, the "shape" of the Target, a good trigger, concentration, physical condition and mostly "Trigger Time".

Parallax can be eliminated at most distances if you have an Adjustable Objective scope and use it properly. You can't just go by the increments on the adjustment ring, but have to match it up to your eyes.

Make some large Black squares and shoot at the corners rather than using a circle. Just snug the crosshair right up to a corner and your opportunity for being able to repeat the process is significantly improved.

If you have not had your Trigger Tuned to a crisp release, do so. Actual "weight" of pull is less significant than one which releases without you knowing it is moving at all. Make sure the rifle is unloaded and go in a quiet dark room with it. Get in a comfortable seated position and as s-l-o-w as you possibly can, dry fire the rifle. If you can feel the trigger move, that is bad - get it corrected.

You have to be able to focus on what you are doing without distractions. If you do not know where the crosshair was aligned once the shot was taken, then your concentration is not where it needs to be. This gets more difficult the older you get. And for darn sure don't get to thinking about playing with women, or you might's well go to the house.

If you intake a lot of caffine or nicotine, getting your internal system in balance is difficult.

Trigger Time is the very best thing for you. With it a lot of the things you may be missing right now will be noticable the more you shoot.

everything you do is magnified as the range increases. For instance the accuracy is comprised of 3 things. Accuracy of the gun, accuracy of the ammo, and accuracy of the shooter. Each of these things are piled ontop of the other. at long range this is magnified. In other words lets say you are a good shooter and at 100 yds are capable of 1 minute groups. At 200 this is 2 inches, 300 3 inches etc.. Then if the rifle is 1 minute, you compound those figures on to of the shooter, and then the ammo etc. In all probability most of the group increase is shooter. So what to do?? Shoot more

A 10 mph wind will blow a bullet off course about .7" at 100, but over 7" at 300.

Scope parallax can also easily account for the difference as well.

A 50 fps velocity spread can add .8" at 300 yards.

Sounds like you're doing pretty well, actually! HTH, Dutch.

A 1moa load at 100yds is no garantee of a good load at 300yds, or IMHO at all. 1moa if that is the best it can do, shows a rifle with an accuracy problem. I have found loads that shoot 1/2moa at 100yds but go all over the place at 300yds. It is more likely an unstable recipe where the load looks OK at 100yds, but shows it's inconsistencies after that point.

I have yet to have anything above 224 bore dia move more than a few inches at 300yds with even a strong crosswind. Wind means leass at 300yds than folks think. If it is a steady condition, the group will be tight, just off center due to some drift. Now, if it goes from 2mph to 10mph and witches directions every few seconds, then an eratic group can be seen. I have shot 600yd matches in pretty strong winds and still managed well under 1moa. If the gun AND load are compatable, 1moa to 300yds is very obtainable. If the gun can only manage 1moa at 100yds, I suggest you look at the rifles deficiencies prior to worrying about the load. my .002"

The others have stated it well, I'll just echo some of my own exp. Scope paralex IS a problem. I have a 4.5x14 on my .260ai & have forgotten to dial it in for 300 a few times. Groups open about an inch or so. AS to wind, sorry JustC, @ 300yds it can make a huge diff. regardless of caliber. A 10mph wind @ 90deg can push you 3"-4", how can that not affect your group size? Maybe not an issue when hunting big game but definetly hurts the groups size if its swirling/changing.

fred, you misread my reply. I said as long as it was a steady condition, it could be tight, just pushed off by windage defelction, but a steady condition can yield great groups just as much and even more than a non-wind condition due to it's removal of the boiling affect of mirage and the subsequent movement of the target/crosshairs. If the BR crowd can draw in a .3-.4moa aggregate at 200yds with a 6ppc in a windy condition, then surely wind is not as much a problem as the shooter who can't shoot in it. And, if the rifle won't shoot an aggregate of less than MOA at 100yds, then asking it to go MOA at 300yds is far from realistic.

The way I see it, it needs to be shooting better at 100yds now, before looking for MOA at 300yds. Wind only matters a great deal for 300yd purposes, when it is eratic, and there is no use discussing wind variables in the case of a rifle that most likely won't do it on a day with no wind at all in it's current state. I think there has to be a better load for it than the current load, that would be where I would start (other than checking lug contact, barrel channel contact, etc) Only after it can run sub MOA at 100yds, does he need to worry with what the wind variable is doing to his 300yd groups. YMMV

quote:

I have yet to have anything above 224 bore dia move more than a few inches at 300yds with even a strong crosswind.

Now come on justC, that's your exact quote above. First of all, a .400 BC bullet moving at 3500 fps will be deflected 6 inches at 300 yards by a 10 mph crosswind. That's not insignificant. Second, caliber has nothing to do with it. A 224 bullet with a BC of 400 will be deflected no more or no less than a .308 bullet with a BC of 400 as long as they are both travelling at the same velocity. That's Physics 101.

Ray

I said I havn't had a pill move more than a few inches, that's correct. BUT, I am not foolish enough to waste my time with load developement in a FULL VALUE, 10mph crosswind with tiny little pills, or even the 216gr clinch river that I launch at 3208fps with a computed BC nearing .700!!!!! The only thing a balistic chart knows is that a wind value is a constant,..which does not exist in the real world. A wind at full value, increasing and decreasing, will affect the group size as each pill has either more or less force applied to it than the previous pill. That is the group opening up, NOT the wind itself,..it is the increase/decrease from the last shot. If it were possible to create a STABLE and CONSISTENT full value wind, you would see the groups remaining very consistent, just blown to one side or the other. That is almost impossible to do without a labratory for such environments and is never going to be a reality in the field. The change in the value of the wind is the reason for dispersion, not the wind itself.

AND, back to my point, offering advice on windage affects at 300yds, on a rifle that at this point has only produced a 1moa group at 100yds, is skirting the issue. No offense guys, but that rifle and load need more work LONG before it's operator needs to worry about wind. If it isn't a sub MOA at 100yds consistently, then asking it for 1moa at 300yds is like asking a VW to get faster as the track gets longer,.....ain't gonna happen. The wind doesn't matter yet,...cause IMHO even in a ZERO VALUE wind, that rifle will be strugling to get anywhere near 1moa at 300yds if it is only 1 moa at 100yds.

And I maintain, that even in a wind strong enough to keep the full sized american flag standing at no less than 45* in a 600yd match last winter, I dialed in 1/2moa windage at the most to be in line with the x-ring. That is only 3"+/- at 600yds, but then again that is a 308dia pill wieghing 200grs and leaving at 3100+fps from a 30" barrel. Your mileage may vary, mine is on targets scored by the judges.

balistic tables are only a reference point as I have sadly proven time and again. My BC was input at a generously larger figure than sierra gave it, and even so, at 1000yds the pill was still 2.5moa higher than the chart indicated after inputting an INCREASED BC value over the sierra data. With a known MV, temp, altitude, etc, and a generous BC value, the chart was off by 2.5moa (25"+ at 1000yds). More often than not, the chart is wrong and must be adjusted to reflect real world values. If the BC calculation is wrong, which is the most often made mistake on a dope chart, the drop AND drift values are also wrong. Prove it,...then beleive it. Testing loads in the wind is an excersize in futility.

And again, until that rifle is capable of 1moa at 300yds in a ZERO wind situation, there is no need to speculate about the wind, cause it won't matter anyway. If you want 1moa at 300yds, then find the right load and whatever needs to be addressed with the rig first, and prove it in a zero wind situation. Then and only then will the reasoning behind the group starying outside 1moa, point to wind and/or operator error. Eliminate the mechanical variables first,..then worry about the environment.

Well you have cut through the and joined the real world of shooting..Had a non internet experience, called a reality check!

And I maintain, that even in a wind strong enough to keep the full sized american flag standing at no less than 45* in a 600yd match last winter, I dialed in 1/2moa windage at the most to be in line with the x-ring. That is only 3"+/- at 600yds, but then again that is a 308dia pill wieghing 200grs and leaving at 3100+fps from a 30" barrel.[/QUOTE]

Just c

I probably agree with most of what you're saying. But, I also shoot 600 yard. Nbrsa benchrest. My best long range rifle shoots a bullet with a BC of 698 and the wind deflection from a 10 mile per hour crosswind is 18" or 3 MOA. I don't know how much wind it takes to keep a flag flying at 45 degrees but will assume it's at least 10 mph. Now if you have a cartridge that only requires 1/2 MOA adjustment at 600 that is one magic bullet.

Ray

nothing I think is especially great, it's a 200gr matchking launched from a 300RUM in a 30" PacNor. The chamber is tight and the throat is not a mile long. That was one cold ass day in january when it hurt to touch the metal of the rifle for very long, don't miss that match at all.



that's 2 clicks on the NXS, but shows what happens when someones boy was more interested in playing grab ass with the other kids in the pits than he was in marking spotter shots. He showed me another POI that he hadn't pasted and I adjusted to it, like a dumbass.



That's what happens when the wind picks up a bit more,..but still only about 3inches avg with the far right being either a gust or operator error which is not at all outside the realm of possibility. This is just a 200gr mathcking at about 3100fps seated a few thousandths into the lands with 88.0gr H1000.

I agree with both sides of the arguement somewhat, and disagree somewhat.

My advice to him would be to do more shooting at 285 yds. No, he won't set the world on fire but this was obviously one of, if not the first time he has ever done it. Can't expect perfect results on his first try consisting of one single group. All the little variables people have mentioned will only be worsened by inexperience. No sense in fretting over/spending a ton of money on the rifle or ammo before he's practiced a little bit first.

So blakeroth, put that target back out there and shoot some more groups! You'll get better with practice and you'll learn about all the stuff people are saying here.

Yes, poor conditions can make it difficult to evaluate loads for accuracy--but it's not like we're talking about 600 or 1000 yds here guys. It's only 300. And it can be just as wrong to assume the load that shoots the best at 100 will shoot the best at 300. In fact, most of my favorite loads have shot their best groups ever (MOA-wise) at 300 and 400 yds. Decent conditions of course, but certainly not perfect. I don't fret too much over 100 yd accuracy. To me it doesn't mean much until it's proven out where it matters.

quote:

Originally posted by Hot Core:
Make some large Black squares and shoot at the corners rather than using a circle. Just snug the crosshair right up to a corner and your opportunity for being able to repeat the process is significantly improved.

That's absolutely the best tip I've seen in awhile, and will certainly help in the situation at hand. Thanks.

RSY

quote:

I don't know how much wind it takes to keep a flag flying at 45 degrees but will assume it's at least 10 mph.

Depends on the flag, but a standard range flag would indicate 15 mph. @ 45*.

Another condition not mentioned, unless I missed it, is mirage. Mirage is affected by wind and carries the image of the target with it. In calm conditions, the mirage often swithches back and forth or boils. In other words, the target is not where it appears to be, moving in the same direction as the mirage.

My rifle is affected a bit more by wind @ 600 yards, but am only pushing a 190 gr. match king @ 2350 fps.

Shooting from prone position w/iron sights, this
3" spotter was placed in my first record shot @ 600; the next 14 shots hit the spotter and the last took out the wooden spindle and blew a 6" hole in the target.




For some reason cannot post full sized pictures on this new sopftware; will try a thumbnail:



Unfortunately conditions changed during time required for target repair; don't ask why the last 5 shots were not on the spotter.

Best advice blakeroth has received so far is to spend more time shooting @ long range and the rest will come in time.

Regards,
hm