Strange Brew???

mikeystew

mikeystew

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so i worked up some 125g .303 brit loads today at 1 grain intervals weighing 43, 44, 45, and 46 grains, and the 5 shot group results were perplexing to say the least...all groups were at 70m

-the 43 grain load had a very tight 3 shot cloverleaf and 2 shots touching 3"low and 1" right.

-the 44 grain load had a very tight 3 shot cloverleaf and 2 shots touching 3"low and 1" right

-the 45 grain load had an even tighter 3 shot cloverleaf and 2 shots nearly touching... wait for it... you guessed it, 3" down and 1"right

-the 46 grain load had a very uniform 3.5" group

All groups were 4" lower than a factory 180 grain federal group which made me scratch my head yet further... any ideas? im befuzzled
 
You made no mention of the powder. In my book, in all powders listed, you are still low in powder amounts. Did you measure the amount or did you weigh each charge? Different casing manufacturers?
 
all federal fireformed cases trimmed to equal length and collet neck sized only, with RE15 weighing each charge exact, sierra prohunter bullets weighed and sorted, and CCI primers... and i figured the #'s may have been low but the only data i had to go by was for a 150grain load so i started 1 grain above the 150 start load, there was no mention of the RE15 for 125 in the lee data sheet or in my hornady handbook... i may need a loadbook for this one.
 
mikeystew said:
so i worked up some 125g .303 brit loads today at 1 grain intervals weighing 43, 44, 45, and 46 grains, and the 5 shot group results were perplexing to say the least...all groups were at 70m

-the 43 grain load had a very tight 3 shot cloverleaf and 2 shots touching 3"low and 1" right.

-the 44 grain load had a very tight 3 shot cloverleaf and 2 shots touching 3"low and 1" right

-the 45 grain load had an even tighter 3 shot cloverleaf and 2 shots nearly touching... wait for it... you guessed it, 3" down and 1"right

-the 46 grain load had a very uniform 3.5" group

All groups were 4" lower than a factory 180 grain federal group which made me scratch my head yet further... any ideas? im befuzzled
Click to expand...

Adjust your sights 3in. higher and 1in. to the left and go with the 45gr load:p KD
 
You didn't mention what type of rifle and how long between shots/strings.

Given that you got the same distinctive result three times in a row, it sounds like it might be the barrel heating up and touching the forestock. Have you free-floated the barrel?
 
dixda said:
Adjust your sights 3in. higher and 1in. to the left and go with the 45gr load:p KD
Click to expand...

oooh you're quick! :D
it's a free floated parker hale No4 mk1... damdest thing, it shot a 2" group at 100m shortly after with the factory fed 180's... i'll try again this weekend and see what develops.
 
Dont be befuzzled - its normal for different bullet weights to have a different POI. I've seen variances as much as 8 inches at 100y.
BTW - Sporter LE's generally shoot better with some support at the foreend. Check to see if your foreend hasnt developed a wiggle - it could be the reason why your last group opened up.
 
mikeystew said:
oooh you're quick! :D
it's a free floated parker hale No4 mk1... damdest thing, it shot a 2" group at 100m shortly after with the factory fed 180's... i'll try again this weekend and see what develops.
Click to expand...

If it's the No4 mk1 it may need to be upgraded to the mk2 trigger system.
IIRC The mk1's had their trigger attached to the triggerguard and were subject to shifts in poi depending on the humidity.
Which is why the mk2 has the trigger attached to the receiver. KD
http://enfieldrifles.profusehost.net/
 
Others have covered the most likely causes of shifting POI within a group. As for the lighter bullets hitting lower, this is quite common. The heavier bullets start moving slower than the lighter ones and spend more time in the barrel, allowing more time for the rifle to rise in recoil before it exits, thus a higher POI. Clear as mud? :D
 
what makes me wonder the most is why the factory 180's always dump into a 2-2.5" group at 100m... every time with no shift in POI. then 3 groups each with distinctive tight yet seperate POI groups, followed by 2, 5 shot groups of factory into 2" at 100m again.
(insert scratchhead emoticon here)
 
Curious.

The usual suspects having been eliminated, how about my going out on a limb and suggesting the rifling might not be suitable for such light bullets. That would tend to cause general dispersion, but still wouldn't explain the three-on-two-off biz.

That repetitive pattern keeps leading me back to a hot barrel touching wood and getting pushed out of true, but you say it was free-floated. Damfino.
 
Barrel harmonics.
The barrel vibrates as the shot is fired. If the ammo is all identical, then in theory the virabtions should be too.
Change a component (powder wieght or type, bullet weight or type, etc...) and the harmonics change.
It could just as easily stayed the same elevation, but shifted sideways 2 inches.

So the moral is to sight in with the ammo you plan to use for hunting, etc.
 
mikeystew said:
the only data i had to go by was for a 150grain load so i started 1 grain above the 150 start load, there was no mention of the RE15 for 125 in the lee data sheet or in my hornady handbook... i may need a loadbook for this one.
Click to expand...

From the Lee manual, 303 Brit, 123gr bullet and reloder15, starting load: 45.6gr @2793fps, Max load 49.8gr @3015fps. The Max load is a compressed load.

You said that your 46gr group was "uniform" and it is just above Lee's starting load. Maybe try working up towards the Lee max load and see if you get any improvement.

Jim
 
Now we're confused ... you're original post showed constant POI for the 125 grainers, then you state otherwise in post #10?
As mentioned above, your rifle will display varying performance as you change bullet weight (and barrel residence time) This is a reloading fundamental, and a major reason why reloaders play with bullet weights! You need to spend more time at the range...
 
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cosmic said:
Now we're confused ... you're original post showed constant POI for the 125 grainers, then you state otherwise in post #10?
As mentioned above, your rifle will display varying performance as you change bullet weight (and barrel residence time) This is a reloading fundamental, and a major reason why reloaders play with bullet weights! You need to spend more time at the range...
Click to expand...

I think you misunderstood my post(s). the 1st post did not show constant POI for the 125g, rather it showed a consistant and repetetive shift of POI with each group besides the last. i will admit i hadn't considered the barrel residence time accounting for the lower impact compared to the 180 grainers, but like i said before each pre fireformed case was trimmed to equal length and each bullet weighed to within 0.5 grain and pre measured base to ogive to ensure uniformity.

what im trying to convey is the point that factory loads always group very well, while my 125g reloads group even better aside from the fact that they shift POI.

As for range time... i work less than 2min from my club and spend nearly 2 hrs there, 5 days a week, and am very proficient with the calibers i am already familiar with. im just new to .303 brit and the 125's are the first bullets i've found available to reload it with, and also the first time i've experimented with a light bullet of any kind in a large rifle caliber.
 
I'm gonna go with rifling. The #4 was designed for a 174gr bullet. that's pretty much a 180 gr. It will generally shoot a 150 gr quite accurately, but may not like the 125's. My first rifle was a 1898 Lee Calvary Carbine. It shot factory 180's into a 4" group at 100 yds. However, when I ventured into the world of reloading, I knew nothing about what I was buying and the guy at the store sold me 150 gr's. I loaded 20, went to the range and couldn't keep anything in a 10" group. and no way of predicting where the rounds would go. I threw all of that reloading crap into a box and shot factories for a couple of years. One day I ran into the guy who sold me the lee loader and he asked how I liked reloading my own. So I told him. He asked me to bring the rounds I had made to his house a few nights later. Went to his house, he has a range out back, where he proceeded to load 150 gr rounds for the rifle. Cleaned the rifle, fired the rounds, 10" group. Fliers everywhere. Then he fired some 174's he had loaded, 5" grouip, the factory 180's again grouped at 4". Then he loaded some 215 gr bullets and fired them - 2" group at 100 yds!! He then explained about rifling, bullet weight, and stabilizing. I did some studying since then and I know that that rifle will shoot 215's into 2" ALL day, but will still group 150's in 10". I made up a bunch of 125's for my 303 this winter. Dang, I was hoping they'd be nice rounds. See what the P-14 does with them.
My $.02.
 
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