Bullet drop way off estimated

[Dougy]

This is one for the target chaps i think, or anyone with excal,

 

I have just sorted out a decent load for my recently re barelled 22.250 well about 12 months ago, but ive been busy on my house.

Anyway, grouping at 100 is a nice 8mm group

 

OAL 2.5355

powder H380-39gr

vel 3920 (fast i know)

bullet 50grn nos bt

zero 125 yds

26" barrel

 

now according to as many ballistic calculators i have found i should only be dropping about 15cm @ 300yds so the question is,

I have found to be about 21cm so were does the extra drop come from surley they cant be that far out, or can they

[snowz]

whats the BC of your bullet,

whats the scope height above the bore

is that actual FPS or estimated

altitude

temp

humidity

 

 

any ballistic program is only as good or accurate as the info put in it.

 

c r a p in c r a p out

Edited September 15, 2011 by snowz

[Dougy]

whats the BC of your bullet,

whats the scope height above the bore

is that actual FPS or estimated

altitude

temp

humidity

 

 

any ballistic program is only as good or accurate as the info put in it.

 

c r a p in c r a p out

 

All info was correct including humidity

line above bore 1.5"

bc 0.236

alt 274

temp 16f

velocity 3925 alfa chrono

hum 78%

Edited September 15, 2011 by Dougy

[Mungler]

The answer lies within a packet of Winchester Supremes, available from all good shooting outlets

[wymberley]

Sierra Infinity agrees with the 15 ish and reflects an MV of 3500 for the 21 (fair old mix of units). Is the MV correct is the first thing to check and then perhaps physically check the drop at various ranges. Also, check the environmental parameters, forget about the cross wind - that's fairly obvious, but shooting slightly downhill at 300 yds doesn't require too much of an headwind to drive a bullet down a bit.

[snowz]

just ran it through EXBAL quickly with the above info and getting

 

6.9" drop @ 300 yds from 125 yd zero

 

 

ballistic programs dont always show exact drops but should be quite near. You will need to tyr a few different ranges to confirm drops then tweek a chart

[Ackley]

This is one for the target chaps i think, or anyone with excal,

 

I have just sorted out a decent load for my recently re barelled 22.250 well about 12 months ago, but ive been busy on my house.

Anyway, grouping at 100 is a nice 8mm group

 

OAL 2.5355

powder H380-39gr

vel 3920 (fast i know)

bullet 50grn nos bt

zero 125 yds

26" barrel

 

now according to as many ballistic calculators i have found i should only be dropping about 15cm @ 300yds so the question is,

I have found to be about 21cm so were does the extra drop come from surley they cant be that far out, or can they

its usually the BC of the bullet,the makers claim a hugh high BC and when you actually field test your data you find its slightly out,you have to fudge the BC figure to corespond with your actually drops on the field target

this is a pefect example for the people who think setting there rifle 1 inch at 100 is going to get them to 300 yards

[pigeonstool]

50 gr bullets don't really like speeds higher than 3500 ft/sec - try backing off the load - mine is H380 powder = 38 gr for 50gr bullets !! I'm also confused with your figures as Hodgdon quote =

 

Bullet Weight Gr.)Manf Powder Bull.Diam. C.O.L. Grs. Vel. (ft/s) Pressure Grs. Vel(ft/s) Pressure

50 GR. SIE SP Hodgdon H380 .224" 2.350" 38.0 3562 41,700 CUP 41.0 3742 45,300 CUP

 

yours = 2.5355 39.0 3920 39.0 3920

 

I use Nosler boat tail 50gr ballistic tips and zero at 175 yds to get a drop 2" @ 250 - this gives me approx zero @ 60 yds > 2" above zero @ about 100 yds ... i.e. a 4" diam point blank.

 

your thoughts?

[Dougy]

50 gr bullets don't really like speeds higher than 3500 ft/sec - try backing off the load - mine is H380 powder = 38 gr for 50gr bullets !! I'm also confused with your figures as Hodgdon quote =

 

Bullet Weight Gr.)Manf Powder Bull.Diam. C.O.L. Grs. Vel. (ft/s) Pressure Grs. Vel(ft/s) Pressure

50 GR. SIE SP Hodgdon H380 .224" 2.350" 38.0 3562 41,700 CUP 41.0 3742 45,300 CUP

 

yours = 2.5355 39.0 3920 39.0 3920

 

I use Nosler boat tail 50gr ballistic tips and zero at 175 yds to get a drop 2" @ 250 - this gives me approx zero @ 60 yds > 2" above zero @ about 100 yds ... i.e. a 4" diam point blank.

 

your thoughts?

 

The figures are correct, well the measurements re- oal,powder and velocity. the 26" barrel will make a difference with regards to velocity if your guide used a 24" barrel.Many books show a variation in velocity's anyway nosler #5 shows 39gr 380 @ 3742- and 41@ 3897 so we know the manuals are not consistant. So 3925 wont be far from correct if i thought the chrono was suspect.

The seating depth was measured a number of times to gain an average using a bullet seating gauge, also checked for marks around the bullets after seating by using a marker pen to double check seating depth.

 

I will most probably back of 0.5 grns but it still wont answer the question.

 

 

Snowz: thats not far away from what i thought hence the post.

 

wymberley : thanks that also tied in with what i found roughly.I was elevated slightly probably 7ft not enough though to make that much difference???

 

and Ackly, Thanks. There isnt a problem getting to 300 yards as a stated, it was the drop i find hard to reach a conclusion to, but thanks for your thoughts.

[pavman]

I only shoot factory loads just now but IMHO drop needs to field tested and taken account of for each load and set up a calculated drop is after all a guide..... This was very evident when some years back we tested the HMR wookies programme said one thing and my crib sheet i had made up by testing said another. In the end my crib sheet proved to be right because it was based on fact, my rifle, round, distance, drop accounted for and dialed in,,,,,

[Dougy]

I only shoot factory loads just now but IMHO drop needs to field tested and taken account of for each load and set up a calculated drop is after all a guide..... This was very evident when some years back we tested the HMR wookies programme said one thing and my crib sheet i had made up by testing said another. In the end my crib sheet proved to be right because it was based on fact, my rifle, round, distance, drop accounted for and dialed in,,,,,

 

Pav thats what i have done i'll be it at only 100 and aprox 300 (so only at 2 points)thats why i am questioning the other info, but there seems to be too much difference between one and the other

 

just popping out now to check the distances again, i hope they were wrong

Edited September 16, 2011 by Dougy

[Dougy]

The answer lies within a packet of Winchester Supremes, available from all good shooting outlets

 

 

Yea !!! rite !!!

 

not long to go

[pavman]

Pav thats what i have done i'll be it at only 100 and aprox 300 (so only at 2 points)thats why i am questioning the other info, but there seems to be too much difference between one and the other

 

just popping out now to check the distances again, i hope they were wrong

 

 

But you have a 2 inch diff between what the prog says it will be and what it really is @300 I would not worry about it just allow for it, most of us seldom shoot beyond 300 in the field so it should not be a problem.........

 

When we did the first HMR test a few years back it was as so many posts claimed a flat path to 150 if you zero at 100 which some of us said was hog wash....... so we tested and on avg found I think it was a 2 inch drop from 100 to 125 ish and after 150 it really fell off. So i made up a sheet of clicks for drop at any given distance between 100 and 300 based on my field tests and it was no where near the prog wookie had on his computer. We then shot out to 300 and mine hit and wookie never got one on the card as they all fell short. Wookie only did what the prog said to test it and he is by all accounts a very good shot and was on avg better than me on the day, so the way forward is i guess is by all means make a ref to a prog but the acid test is what happnes in the field and thats what you need to allow for not predictions.......

Edited September 16, 2011 by pavman

[Ackley]

The figures are correct, well the measurements re- oal,powder and velocity. the 26" barrel will make a difference with regards to velocity if your guide used a 24" barrel.Many books show a variation in velocity's anyway nosler #5 shows 39gr 380 @ 3742- and 41@ 3897 so we know the manuals are not consistant. So 3925 wont be far from correct if i thought the chrono was suspect.

The seating depth was measured a number of times to gain an average using a bullet seating gauge, also checked for marks around the bullets after seating by using a marker pen to double check seating depth.

 

I will most probably back of 0.5 grns but it still wont answer the question.

 

 

Snowz: thats not far away from what i thought hence the post.

 

wymberley : thanks that also tied in with what i found roughly.I was elevated slightly probably 7ft not enough though to make that much difference???

 

and Ackly, Thanks. There isnt a problem getting to 300 yards as a stated, it was the drop i find hard to reach a conclusion to, but thanks for your thoughts.

Hi mate seems like you are doing everything right burt as I said the programmes are not pefect all the time due to the BC published data of the bullet your using.

you need to get your data and field test it at various distances and then adjust the programm setting namely the BC number to match your actual field data,I do have a DVD by best of the west "how to shoot beyond beleif" which expalins the therory behind it and how to do it.

it shows you the various stage form finding your load and velocity to then field testing,once the correct data was put in to the programme the drop chart was bang on.

you will find some bullets will be perfect using the same programme as there BC is correct and not made up

[al4x]

are you sure the 2" difference isn't due to the curvature of the earth

[Davy Holt]

are you sure the 2" difference isn't due to the curvature of the earth

 

Noooo that only affects the .17HMR

[pigeonstool]

I think Pavman is getting close - both 'theory' from the tables and field test on a range with my Remmy BDL 700 showed a very fast drop-off over 250 yds - so I set-up for an 'across a field' shot at charlie - i.e. if middle of engine box is in cross hairs - he's mine

I seem to remember at 600yds the drop was over 8 foot :blink: and side winds could push it over 2ft off .. so let's face it - most charlies are shot at the 100 to 200 yd range - so go for a simple point & shoot set-up

[wymberley]

Like an accident, there's usually no single cause but a combination of factors. Must say I think A. and his BC remark could be the most significant. It's obvious you're trying to do your best here, so have a look at the 50gr V Max if you haven't already. the 50 is the only one (on paper) that out performs the Nosler

[Dougy]

I will drop the charge a tad and have a go with some Vmax, A day out with the press and loading gear again coming soon certianly interesting stuff

 

seems to have done the trick whatever

both between 130-170 yds

[Ackley]

Like an accident, there's usually no single cause but a combination of factors. Must say I think A. and his BC remark could be the most significant. It's obvious you're trying to do your best here, so have a look at the 50gr V Max if you haven't already. the 50 is the only one (on paper) that out performs the Nosler

when I run a 22.250 the best bullet I found was the 52gr Berger Varmint,loads better quality than the Nosler and V Max and outformed them both

[casts_by_fly]

the difference will be the BC. Almost certainly that BC will be calculated around 3600 or even lower. When you start pushing bullets faster, the BC goes down. With a G1 ballistic model, you'd be around .200 BC for that amount of drop. Going from .236 to .200 by upping velocity 300 fps isn't unreasonable to me.

 

Thanks

Rick

[AnthonyR]

Noslers own reloading manual gives 3742 fps for 39gr of H380 with a 24" barrel using their own 50gr bullet, an extra 2" of barrel should give a max of about 100 fps extra, so I would say your chrono is over-reading by a bit which may account for some of the extra drop.

 

When I was using these bullets I could never match the drop figures either so I would agree with the others that the BC is also probably optimistic

[Kes]

are you sure the 2" difference isn't due to the curvature of the earth

 

Wait till Ackley sees this - are you two born to duel ?

 

Surely its more likely to be due to the phases of the moon - g*m1*m2/d2 and all that ?

[dicehorn]

When you start pushing bullets faster, the BC goes down.

Thanks

Rick

 

Well thats news to me - I thought I had read that BC goes up with increased spead - Viz the 39gr Sierra BK for the 204

 

.270 between 3600 and 3400 fps

.255 between 3400 and 2800 fps

.236 between 2800 and 2300 fps

.210 between 2300 and 1900 fps

[coyotemaster]

That BC seems a little optomistic. The advertised BC for a 50 VMAX is .242 and that has a polymer tip to beat the breeze. I too find most advertised BC's are not always what they say. If you chrono'd it and aren't going by book numbers you have a fast stepper for a 250. I agree wholeheartedly with Snowz ----**** in **** out.