Ballistic simulator for est. of point of impact?

[Mike the Dane]

Hi All,

I just found time to try 5 reduced loads tonight in my winchester 94 .30/30, resulting POI was surprising to me?

The winchester is sighted in at 100 meter / 110 yds with factory ammunition.

The load is 8 grs. of trailboss under a 150 grs. gaschecked Lee boolit, velocity should be 1135 fps according to the Lyman cast boolits manual.

The five shots were taken at my private mini-range (the riding course of my wife actually), so distance only 40 meters / 45 yds. The shots were consistently placed way below the paper target, approx. 12" low?

Now, I did expect this reduced load to be low, but not that much? That brings me to my question - does one of you guys have a program/simulator where you could compare POI of the factory load (170 grs PRVI Partizan) with my load (BC of 150 grs. Lee boolits is .266) - i.e.: if my gun is sighted in with the factory stuff at 110 yds, what would POI be at 45 yards with same sight setting, but using my reduced load?

Anyone experienced excessive "rainbow trajectory" with reduced loads, or is this just physics doing it's bit, and I should stop moaning and just adjust sights according?

Regards

Mikkel

[fecmech]

Yes but you need to know the velocity.
http://handloads.com/calc/index.html

[firefly1957]

Some guns do not shoot the same point of impact with reduced loads there can be many reasons for this including barrel rigidness, muzzle crown,....color of the sky. My point is it may not be the trajectory but another factor. For instance I have a thin barreled Rossi in .223 Rem. it shoots OK when the forearm is held just right but when I use a reduced load (55gr bullet at 1850 fps) it will shoot 6 inches low at 25 yds.! now my mini 14 shoots both loads into almost the same group at 25 yds.!
Many reloading manuals will have ballistic data in the back all you really need is the velocity and the ballistic coefficient to figure drop. If I did this right it does look like your bullet will drop almost three inches more at that reduced speed but the program I used only gives sighting info and not actual bullet drop!!! the program is WW Blackwells load from a disk.

[btroj]

Ballistics software alloys you to see the trajectory of a load but I have never seen one that shows where different loads will impact in relation to each other. They can compare if both loads are sighted in at the same range but You are looking for something different. You are looking for a program to predict how the harmonics of the barrel/load combo will impact point of impact. That is a whole 'mother ball of wax. This is why some guns show a horizontal shift too.

Sadly, you found out the best way to see where loads impact in relation to each other, it involves a target and some ammo.

[303Guy]

Two things cause the reduced load to shoot low. The first and most important is the lack of recoil that normally tends to lift the muzzle before the boolet exits and the second is increased drop from a slower boolit. However, higher recoil can cause the POI to move down, depending on how the barrel whips on firing. (It muzzle can point downward during the upswing as the whip wave approaches the muzzle). It also depends on the configuration of the stock and barrel and action. So, an exagerated low POI with a light load would be quite the expected but not the rule.


now my mini 14 shoots both loads into almost the same group at 25 yds.! My mini-14 was the same!

[Mike the Dane]

Sigh - seems I just have to shoot some more :-)

I can cope with that :-)

Mikkel

[onesonek]

I was think along the lines as 303Guy. If were not trying it already with your low impact reduced loads, try a much lighter hold on the rifle, just rest the forend on a flat open palm on the off hand, and don't lean into it as normal. 12" is a lot, but the above technique may help some.

[Mike the Dane]

Well,

took my load to my 50 yds range and sighted in the new load.

Very pleased with the performance, I fired 40 boolits, the string pictured were shots 30-35, no leading at all.

Single flyer I can blame myself for, got carried away :-)

4 shots measure 15mm (3/5") fired prone from a sandbag at 50 yds. Recoil is like a 22 wmr, so is sound level. Brilliant!

Thanks for all the help, Brett was right in saying hardness isn't that important, ended up casting 80/19/1 lead/lino/tin, no quenching, fitted gascheck and sized to .309" - own panlube from 50/50 beeswax / vaseline and 1 tbsb superlube (has teflon in it, figured it certainly wouldn't harm anything :D

[Cap'n Morgan]

When I lower the speed in my 1885 45-70 Uberti, the point of impact rises quite a bit. Obviously the longer barrel-time allow for more muzzle jump before the boolit exits the muzzle. I blame the ridiculous amount of drop in the stock which seems to be common for a lot of vintage rifle designs - including lever actions. I always wondered why.

[HangFireW8]

I blame the ridiculous amount of drop in the stock which seems to be common for a lot of vintage rifle designs - including lever actions. I always wondered why.

Cheek weld was not the rule back then, some shot with the butt on the arm, not the shoulder, plus prone positions may not involve the upper arm or shoulder at all.

With military arms, anyone can see the sights and shoot with a short length of pull and a lot of drop, but while many find a higher comb more comfortable and more accurate, for some it would rule out seeing the sights all together- unless the head was layed sideways across the comb, not a good way to shoot, nor handle recoil for that matter.

[303Guy]

but while many find a higher comb more comfortable and more accurate, for some it would rule out seeing the sights all together-That explains it. I found myself placing the but on my upper arm instead of my shoulder for sitting shooting just this past week.

[HangFireW8]

That explains it. I found myself placing the but on my upper arm instead of my shoulder for sitting shooting just this past week.

This works fine- for lower power cartridges. It was the norm for Schuetzen, which like many competitions, used cartridges which were just powerful enough to get the job done, and no more.

Teddy Roosevelt ordered his several large bore Winchesters with a "shotgun butt" for good reason. Not everyone was happy with the crescent buttplate on those old thumpers.

-HF

[Mike the Dane]

Thanks for sharing HF, that makes a lot of sense. I also Found the winchester quite hold sensitive, luckily have been shooting airguns for 30 years+ (thanks dad!)

;)

Mikkel

[303Guy]

4 shots measure 15mm (3/5") fired prone from a sandbag at 50 yds. Recoil is like a 22 wmr, so is sound level. Brilliant!Nice grouping! The recoil and sound level is great isn't it!

[Mike the Dane]

Hi 303 guy,

yup - very pleased with this load :drinks:

Just tried it in my scoped H&R 157 rifle - even better than in the winchester, 3 shot group @ 50 yds was 8mm / 0.31" from prone, gun rested on sandbag.

Absolutely no leading - picture taken was last 3 shots after 42 rounds had already been shot (without any cleaning). Two strokes with a soft bronze brush and some breakfree, and the barrel was back to "as new condition".

As a side remark, I found out that an empty .357 mag case (winchester brass) can be used as a dipper for this load - throws 8 grs. of trailboss very effectively :D

So summarize "my load" (it is more or less = starting load given in the Lyman castboolit manual):

Brass: PRVI Partizan
Primer: CCI large rifle
Powder: 8 grs. Trailboss
Lube: 50/50 beeswax / vaseline with a tbsb of superlube (teflon lube). Pan lubed.
Bullet: 150 grs. Lee C309-150-F sized to .309" and fitted with Hornady GC
COL & crimp: Bullet seated to crimp groove, given a light crimp (full length resize die used initially, as I shoot my 30/30 in different rifles)
Alloy: 80/19/1 Pure lead (flashing) / Linotype / soldering tin - Air cooled

This casting thing is very addictive :lovebooli

Regards

Mikkel

[parrott1969]

*#$%& spammers!! Go back to China!!!!