629-6 Classic, lighter bullets lower, heavier higher????

[RIDE-RED 350r]

Kinda have a mystery here. I recently bought a once fired 629-6 Classic 6.5". It patterns great, pretty tight for just shooting rested on a bench with no sandbags at 50'.

But here's the mystery. I sighted it in with American Eagle 240gr JHP's. I was hunting with Hornady Lever Revolution 225gr. I didn't figure at 50' the difference in bullet weight would be drastic. So, I took a shot at a deer at about 50' with it and missed. So, I bought some more rounds and went to the range. Due to a bit of lack for options, I bought a box of 180gr JHP's and went to the range with what I had.

Fired my 8 remaining rounds of 240gr American Eagle JHP, and my pattern was right where i left it after sighting in. Next I tried the 180gr JHP's and here's where it gets weird. The lighter 180gr bullets patterned about 2+ inches lower than the 240gr counterparts. So, I made some sight adjustments and attributed it to different ammo. In the shooting position next to me was my brother with his 29 Classic, 6.5" bbl. He then asked if I wished to try a few rounds of his 300gr Hornady XTP's. So I did. And when I aimed center of the bullseye the P.O.I. was so high it was off the paper! Next round I aimed at the bottom edge of the bull and it hit about 3" above the top edge of the black. Next shot aimed near the bottom edge of the paper and finally got it in the black. I didn't save this particular target unfortunately. So, I decided to try the 6 rds I had left of the Hornady Lever Revolution 225gr that I had been hunting with earlier. And whatya know, with my sights where I left them for zero with the 180gr bullets, the P.O.I. was about 2.5" high. Here's another crazy part, my brother's 29 Classic shoots pretty consistently whether he was sending 180gr or 300gr and everything in between downrange at 50'. And yes, he tried the same exact ammo I was using so it's definatley something with my gun.

The main question is this: Why the heck would my weapon shoot higher with heavier slugs and lower with lighter slugs. Windage patterning was pretty consistent, but elevation was consistently and predictably higher with heavier bullets and lower with lighter. Through all this, I was letting the gun cool completely after every 6 rds and I did switch back and forth to verify this wasn't an effect of the weapon getting dirtier as the round count increased. Is this an issue of break-in? What could cause this? I'm not upset, because all I need to do, is decide what ammo I want to shoot and stick with it. I'm just utterly baffled by this. Here are a couple pics of some of the targets so you can see for yourself.....

Having trouble with the file uploader, have to use photobucket...

This was my first 8 rds with the American Eagle 240gr

Next 6 rds with 180gr JHP, (note how much lower)

This target was the only 6 Hornady Lever Revolution 225gr I had on me. Fired 2 shots, adjusted elevation down, 2 more shots then 1 more click down. The final 2 were right on the money..

This was the last of the 180gr JHP leaving the sights alone after adjusting to what I am currently hunting with. (Hornady Lever Revolution 225gr.) Note how much lower the 180gr shoot than the 225gr.

Again, my brothers 29 Classic with the same length barrel shot all of the same rounds with virtually nil change in elevation at P.O.I.

Sorry for the long winded post and using the Photobucket. Couldn't get my pics to upload with the uploader for some reason.

Any ideas?

Thanks!

 

[OKFC05]

That's not strange, that's normal. Slow/heavy go high, light/fast go low.
The longer a bullet stays in the barrel, the more time the revolver has to rotate in recoil and send the bullet on a higher angle.

 

[lebomm]

Heavier higher

With the heavier bullet, you have the combination of lower velocity and heavier initial recoil (upward movement of the gun while the bullet is still in the bore), resulting in a longer bore time, and higher muzzle when the bullet exits. Using the same sight picture, your muzzle is higher at exit, launching the bullet at a higher arc. HTH
Looks lke OKFC05 types faster than I do.
Larry

 

[CWH44300]

that sounds about right - heavier bullet, a little slower, in the barrel a little longer, the gun is further into its recoil cycle before the bullet exits the gun - sounds about right to me

 

[RIDE-RED 350r]

OK, I never thought of it that way. It does make sense.

One other thing I failed to mention is that my brother's 29 Classic has a scope on it and with the same rounds seems to recoil a bit less than mine. I'm guessing this would make his shoot different weight bullets a bit more consistently? I mean, he has very little difference in P.O.I. elevation whether he fires 180gr or 300gr.......

Is a blued steel revolver of the same bbl length inherently heavier than stainless to begin with??

Thank you all for the explanation. It does make sense, I just never gave it a thought. And never would suspect it would make such a profound difference....

I have only had my pistol license about a year and a half now so my handgun experience is still limited. I am a fairly experienced long-gunner though and one thing I have certainly learned is that handguns are a totally different game from long guns.


On a lighter note... What do you guys thing of my patterns in general? SA, rested at 50'. No sandbags, just resting my hands on the bench.....

I always end up with a stray or 2 that happens when the round goes off before I get fully settled. Guess that will come with more practice and getting to really know my weapon and the point in the squeeze that the hammer falls....

 

[crsides]

Dooman

You sighted in with 240's, the 180's were 2" lower, reset sights, and the 225's were 2.5" high.

That puts the 225's grouping 1/2" low from the original sighted 240's, if I do my math right.

Could be one of those stray's got fired at the deer.


Charlie

 

[lebomm]

BTW, rifles & handguns shoot GROUPS, shotguns shoot PATTERNS. And they're pretty good !

Larry

 

[5-Shot]

Years ago I had a TC with a 14 inch barrel in 44 mag. I normally shot a hot load with 180 grain jacketed bullets. Lightly loaded 250 grain cast bullets shot several FEET high at 50 yards.

Ed

 

[one eye joe]

That's not strange, that's normal. Slow/heavy go high, light/fast go low.
The longer a bullet stays in the barrel, the more time the revolver has to rotate in recoil and send the bullet on a higher angle.

That is EXACTLY what is operant here......

 

[gkitch]

Mystery solved

Heavier, slower bullets group higher.

BTW, I get the best accuracy and performance from 300 gr JHP (Sierra or Hornady) through my 29 Classic DX.

You should keep a hunting handgun fed with consistent loads so you get confident with exactly what it will do. Experiment, then commit.

 

[ultratec00]

I went from 240s to 180s and experienced the same thing for both my 629s and the 29 I used to own. Never had a need to load anything above 240, so can't speak for those.

 

[scooter123]

A couple of thought on this. First, the effect is called Bore Transit Recoil. If you think about it, that is a pretty good description.

Now, it's my personal theory that barrel length has an effect on the amount of Bore Transit Recoil observed. Unfortunately, I don't have multiples of specific caliber revolvers in different barrel lengths so my theory is based on observation between revolvers of different calibers. What I've seen is that longer barrels tend to increase the amount of the shift in POI due to different bullet weights. As for why I think this, pretty simple, longer time in the barrel means more time for the shot to be "thrown" during recoil. End result is that I would expect to see less variation due to bullet weight with a snubby than with a longer barrel.

Second thing about long barrels is that in my case I found that they test your recoil management skills a lot more than a shorter barrel. When I first got my 6 1/2 inch 610-3 I shot it pretty poorly and it took me a bit of time to figure out the cause. It wasn't the gun, it was all me. I was "throwing" shots because I just wasn't consistent enough during recoil. After a bit more than 2 years I'm now shooting it well, but it was more difficult to get there than I expected.

 

[CWH44300]

A couple of thought on this. First, the effect is called Bore Transit Recoil. If you think about it, that is a pretty good description.

Now, it's my personal theory that barrel length has an effect on the amount of Bore Transit Recoil observed. Unfortunately, I don't have multiples of specific caliber revolvers in different barrel lengths so my theory is based on observation between revolvers of different calibers. What I've seen is that longer barrels tend to increase the amount of the shift in POI due to different bullet weights. As for why I think this, pretty simple, longer time in the barrel means more time for the shot to be "thrown" during recoil. End result is that I would expect to see less variation due to bullet weight with a snubby than with a longer barrel.

Second thing about long barrels is that in my case I found that they test your recoil management skills a lot more than a shorter barrel. When I first got my 6 1/2 inch 610-3 I shot it pretty poorly and it took me a bit of time to figure out the cause. It wasn't the gun, it was all me. I was "throwing" shots because I just wasn't consistent enough during recoil. After a bit more than 2 years I'm now shooting it well, but it was more difficult to get there than I expected.

Right you are sir - I have multiples of 4" 6" 7.5" and 8.375 " sixguns and your theory is right on the mark and thanks to the329 series weight is also a big facter, with the 4" 329's being just as sensitive as the longer barreled steel framed guns - in some cases more so

 

[RIDE-RED 350r]

Thank you all very much for insightful replies!

Yes, that 225gr Hornady was the one fired at the deer that missed. I suspect I shot under her.

I have some 200gr Hornady XTPs loaded to 1600fps with H110 powder on order right now. When I pick them up, I intend to sight in on those rounds and stick with them.

But while I wait for those, I am sighted in on the 225gr Hornady Lever Revolutions, and that is what I'm loaded with when hunting. Shouldnt miss next time!

 

[CWH44300]

Thank you all very much for insightful replies!

Yes, that 225gr Hornady was the one fired at the deer that missed. I suspect I shot under her.

I have some 200gr Hornady XTPs loaded to 1600fps with H110 powder on order right now. When I pick them up, I intend to sight in on those rounds and stick with them.

But while I wait for those, I am sighted in on the 225gr Hornady Lever Revolutions, and that is what I'm loaded with when hunting. Shouldnt miss next time!

good luck - hope you enjoy back straps has much as I do
HE..HE

 

[RIDE-RED 350r]

good luck - hope you enjoy back straps has much as I do
HE..HE

You betcha!

 

[44wheelman]

If two guns were sighted in with 240 grain bullets; then each gun were loaded with 300 grain bullets; which would shoot higher: a 2 5/8" bbl or 8 3/8" bbl?

I'm guessing the heft of the longer bbl will keep the muzzle lower and therefore, shoot lower.

 

[38-44HD45]

If two guns were sighted in with 240 grain bullets; then each gun were loaded with 300 grain bullets; which would shoot higher: a 2 5/8" bbl or 8 3/8" bbl?

I'm guessing the heft of the longer bbl will keep the muzzle lower and therefore, shoot lower.

The opposite is true. Shorter barrels don't have time to rise as much in recoil. Longer barrels magnify the effect. Also, the effect is generally seen less in autoloaders than in revolvers, because of the lower borelines of autos.

 

[RIDE-RED 350r]

The opposite is true. Shorter barrels don't have time to rise as much in recoil. Longer barrels magnify the effect. Also, the effect is generally seen less in autoloaders than in revolvers, because of the lower borelines of autos.

Am I correct to assume that this effect is less significant in less powerful calibers as well??

I also spent time firing my 6" 686 that night. It was one of the other weapons I brought to the range and was rotating into the mix. That piece doesn't care if I feed it full house mags, or 38spl. It groups nearly identical.... at 50' anyway. I use the same bullet weight in 38spl as I do in 357mag.....158gr.

 

[38-44HD45]

It's not necessarily just how "powerful" the cartridge is. The heavier the gun, the less effect one sees. The greater the recoil/muzzle flip, the greater the effect, so lighter guns show it more. Even how tightly the gun is held makes a difference. A great way to illustrate the effect of grip strength on POI is to use something like a .45 Colt SAA with a 7 1/2" or longer barrel. Shoot it one handed, holding it loosely, then hold it as tightly as you can with two hands and repeat, shooting at the same target at the same range. Bullet impact for the first shot will be much higher than the second, assuming you did everything correctly and didn't yank the trigger.

However, if velocities of two different bullets of different weights are both relatively high, for example one running at 1300 fps. and the other at 1500, the effect on POI is less extreme, because the bullets exit the barrel more quickly, before it has a chance to recoil as much. There are many variables, but the basic mechanism affecting the degree to which POI is altered is pretty simple: How much does the muzzle rise before the bullet exits?