Home Forums Hunting & Shooting Ask The Gunwriters Can someone explain 11" extra drop at 300 yards?

Sunspot activity.

yeah, but even a rock with a parachute wouldn't drop that much more between 200 and 300 yards! Well, I might be exagerating, but you get the idea.

As an added thought, I`m sure your 200 and 300 yard distances were correct too? Were your distances calculated by a rangefinder in good working order?

Scope zeroed in correctly at 200 yards and nice and tight?

If all the tees are crossed and the eyes are dotted and there are or were no drastic down range wind flurrys, then I would go back to the bullet itself and start with a bullet swap!

I think I would try to borrow another chronograph, either that or you loaded the wrong powder by mistake? SWAG
whelennut

I'm the guy who started the thread. I just went downstairs and pulled several bullets. It is the right bullet. It is the right powder and charge weight.

Rick, thanks for the heads up on being that high over book with that load. I thought I read 47 was max with that load. (Reloader data on their net site.) I worked up to it, and the hotter it got, the smaller the groups got. I'll back off so I don't get myself this summer when it gets hot. So far, no sticky bolt lift and the primer pockets don't feel loose. Primers look fine, too. I get the same speed with the same components with 165 SSTs, so didn't think too much of it.

Digital Dan, it's 300. That bench at the range is for the 200 and 300 yard boards. The 400 yard section is down the road. The scope is maybe 1.5 inches above the bore. I didn't measure it, but it's low .

RR, I didn't touch the scope adjustments. I had put up two big pieces of butcher paper with an aiming point on the top. I hold on that aiming point. I always do this to measure drop.

Guys, all I can think is that the reticule cell shifted, or went "sproing", between my 200 yard shooting and the 300. I know that is a huge coincidence, but that is all I can think of. I'll try to head back out Wednesday and confirm my 200 yard zero. I should have done it before I left but I was out of time and about ready to start pulling my hair out. Before I moved to 300, I shot two, three shot groups that were both just over two inches and dead in the bulls eye. The gun wasn't dropped or anything like that.

Guys, I don't think this is a bullet problem. These loads are grouping great. If the wind dies down, it has been under an inch at 100 and at two inches at 200. If I do need to switch bullets, do you have any other AFFORDABLE bullets I should try? I've already read the "Good 308 loads" in the reloading forum. If I need to slow this bullet (the 165 Sierra HPBT Gameking) down four grains (200 fps?) to be safe, this bullet, with it's low b.c., isn't gong to line up with the B and C reticule in the scope at all.

I don't want to try the old Speers because they are going to be replaced, and I don't see the new ones out yet. I've heard lots of good things about the Horn. 150 flat base, but I'm thinking with that sectional density it would be too light for elk. I did try the 150 SSTs, thinking I could use the interbonds for elk and the SSTs for playing. The gun liked these the least, at about two inches at 100 yards, with R15, R17, and H4831. I tried The 165 interlocks and SSTs. All of those bullets, with the other components, are 1.5 to two inch loads. I'm not happy with that. The gun groups the 180 interlocks great, but they are only leaving at 2580. I think impact velocity would be too low for expansion on a longer shot.

But, again, I don't think it is a bullet problem, I'll head back out. I've never seen this before and am wondering what dumb thing I'm overlooking or did wrong!

Thanks for the help and I'll post what I find after my next time out.

I've seen stranger coincidences than that, a re-shoot is definitely in order. I can't imagine what could've caused so much drop at 300 short of a major transient in the gravitational constant of the universe. Or it could be those immodest earthquake causing women that some Iranian cleric was gassing on about.

call rich matcholz at serria ask him and explane your problem there great to work with .They put you in the right place to go and what up with your set up tell him rudy sent you from mi .Goog luck. 400 yard should drop around 24 inch an 8.5 or so with 300 yard with 200 yard zero

Understood and I agree.

You need to know what the scope height is. Otherwise is skews the ballistic calculation. Realize this sounds like quibbling but it really isn't. 1.5" is a standard reference..you say "low"...might not be the same thing and having a lower scope will have the effect you're experiencing as I understand it.

My money is on the bullets not all being the same type, ie 150gr mixed with 165gr weight. Either that or they are mixed up with guilding metal / copper only bullets of the same shape & length. The only way to find out is to weigh all of the bullets but I'm betting on different weights due to inconsistencies in the amount of lead etc. in the bullet. Also, if these were non lead bullets mixed in with lead bullets, regardless of the shape and overall size they would act differently, especially at longer ranges. The fact that you are able to use a hotter load than usual for this weight of bullet would also be indicative that they are not lead or contain a less dense material than lead in the bullet. Finally being of lighter weight, they should drop faster at extended ranges.

Flower Child

A brief suggestion if one repeats the exercise. Try a series of shots with round one at 100, rnd 2 at 200, and 3 rd at 300. Repeat until one has 3 to 5 shots on each target. If one shoots exclusive groups at seperate targets, then each target is an independent event. The series approach will at least remove that aspect from your trial.

Buffalo's me completely. Please post your eventual findings.

ID,

What scope mounts are you using? I remember reading an article where the fellow was testing various rifle and load combinations at 100, 200, 300, and 450 yds. The writer had the opposite puzzle. He discovered his .308, shooting a 150 grain bullets at 2800 fps mv. was +1 at 100, +1.5 at 200, -5 at 300, and -31 at 450 yds. The 300 H&H in the test with 165 bullets at 3000 fps mv. was +2.5 at 100, +1.25 at 200, -5 at 300, and -31 at 450 yards. His hypothesis was the scope on the rifle was not mounted parrallel to the barrel. I don't know if that was the case and the cause and I would rather have his "problem" than yours. When you mounted the scope did you check and lap the rings if they needed it?

Probably going to find somthing with the sight setting being off. I looked back through notes on different M1a's and found the 300 yd setting to be 3 min. (clicks) up from 200 yards. That's with anything from 147 gr south african ball (cheap stuff) to 168 smk's.

IDMilton,

I had the identical problem with my Ruger M77RS 35 Whelen. My handloads of 59 grains Re15 over the Speer 250 grain spitzer would shoot about 2-1/2 inches high at 100 yards, and zero at 200. At 300 they were low off the target board. I never did figure out exactly why it happened, but I did figure out how to fix it.

When the problem occurred, the Whelen barrel was free-floated. I was going through a "free-float" phase at the time and floated everything I owned. In desperation I test-fired the rifle with shims installed between the forend and barrel and the problem went away. The 300 yard drop was now closer to 10 inches. So I made the shims permanent and that was the end of the problem.

Incidentally, that Ruger barrel is of standard contour, and a 35 caliber hole doesn't leave a lot of steel, particularly at the muzzle. Consequently, the upward pressure exerted by the forend on the "flexible" barrel raised the POI considerably.

The actual cause of the problem is left to speculation. The theory I came up with says that the "flexible" barrel vibrated quite a bit and released the bullet with a pitch problem (not quite like Randy Jackson complains about). I suppose the nose of the bullet was pitched downward and planed downward. Can anyone prove me wrong? Mike Venturino wrote about a 308 rifle he had that exhibited the opposite problem. He said that rifle shot a bunch flatter than it was supposed to. Now that is a good problem to have. If we could figure out how to repeat that "problem" at will we might have something valuable.

I suggest you install temporary shims for about 5 pounds of upward barrel pressure, and test fire. If it works, make the shims permanent.

Good Luck!

SteveNO will be soooo jealous.........



Casey

I would still try another chronograph.

Velocity causes bullets to shoot flat or otherwise. I would also try another bullet of the same weight and compare the two. Something like a Nosler BT or TSX if you have any would be a good test.

JW

So velocity 100 or 200 fps slower is going to more than double the drop at 300 yards? Not hardly.

Double checking adds value to the research. Criticizing double checking does not.

JW

ID Milton: Did you use the exact same type of rest for your 100 yard zero,that you used when shooting at 200-300? Any changes at all to your positions or the way you were holding the rifle when you shot at 100,200 and 300?

I think Big Redhead is nudging around the source of the problem....

A buddy came here from NY with a Rem 700 KS Mountain rifle chambered for 300 Win Mag. We clocked his 165 Partition handloads at 3100 fps,zeroed from sandbag rests to be 3" high at 100 yards.The rifle shot well.

But at 400 yards,after he had gone to a field prone position,POI was about 20" low.....I knew from past experience with that load,that it should have been about 12" low.He was puzzled, and I told him he had a "false" zero at 100 yards.Because he had a bedded barrel,the rifle was hitting high by bouncing off the firm bags at 100,causing the POI to be high. When he went to the 400 yard line, held the rifle in his hands,this "bouncing" effect was gone,the rifle assumed a different vibration, and hit lower than it should relative to its 100 yard zero,given its' velocity..

The solution in his case was to free float the barrel,which eliminated the bouncing,and his trajectory became more "normal".

But ID Milton has a free floated barrel;so did Big Redhead,so I guess what it all points out is that you cannot depend on trajectory tables to tell the "truth" about YOUR rifle and the only way to determine true POI at various ranges is to shoot at those distances. I guess it also points out that there is some kind of relationship between barrels and forends that can affect POI as well under certain circumstances.

That is what I am thinking also.

The higher that the scope is mounted the flatter the trajectory APPEARS to be,
according to an old Outdoor Life article by J O'connor.

My .30/06 has extra low mounts and shows about 14" of drop at 300
when sighted 2.5" high at 100 yards.