Fired first reloads today! Why was light load tighter groups?

[SamTuckerMTNMAN]

My friend hid behind a tree. . . my dogs ran off. . . my wife went to run or something. . . but I fired my first handloads today! My thanks to all who have helped sort through questions, the list seems endless, and here's another.
I worked up a load from 24.5 grains to almost max at 26.5 grains. The 24.5 had a much tighter group size. Is this normal? Should I always use the light load now for that rifle? I assumed more powder meant better long range stability, and I was shooting at short ranges (see below), but the difference would translate into major adjustments farther off. I'll also include a pic of my first borns
------------------load data----------------
caliber .223, semi auto
69 grain BTHP, Speer (set just deep enough to clear magazine wall)
Remington brass, once fired by me
Win 748 powder
CCI small rifle, magnum primers
loads from 24.5 grains up to 26.5 grains (MAX = 27)
--------------rifle----------
16" heavy, stainless barrel, free floated, 1:8 twist ratio
vortex FS
----------------------------
________________
So, how important is it to reach max load?????

 

[LHB1]

Nice going. Sounds like your rifle told you which of those loads it prefers. Listen to it! You can't always assume that the lightest, heaviest, or whatever load will work best. The proof is in the shooting. The vibrations and harmonics that occur when you fire a rifle are complex. They can and do affect the exit angle and stability of the bullet which in turn leads to better or poorer accuracy from one load to another. The only sure way to see which load is best FOR YOUR GUN is to shoot them in a direct comparison under same conditions.

ps: Keep good records of each load tried (case, weight and type of powder, weight and type of bullet, primer, OAL, etc.) and the results of shooting that load.

Good shooting and be safe.
LB

 

[Bullet]

Congratulations on your first reloads.

Where did you get your loading data? If you go here –

http://nationalbullet.com/index.php?name=Loading_Data

and click on Winchester, the data for 69gr bullets using Win 748 shows a MAX load at 24.5gr.

My Speer manual doesn’t list a 69gr BTHP bullet?

Do you have a chronograph?

 

[Lloyd Smale]

if your loading for an ar or simular semi auto its better not to push the envelope anyway. Youll just end up with cases stuck in your chamber

 

[dfaugh]

IME, (I don't handload , but my buddy does it for both of us) it's rare that the "hottest" loads will be the most accurate. They may be, but rarely. The only way to determine the most accurate loade for your gun, is to do just what you did---start low and work your way up/near max. You probably find a sweet-spot somewher in the middle. Then, if you like, you can make smaller changes to further increase accuracy.

 

[Walkalong]

Generally speaking you will find a happy spot for your load/rifle/bullet were it shoots well. Below that or above that your accuracy will not be as good. It is different for different combinations. You just have to experiment. Nice shooting for your first try. You are well on your way to finding something your rifle will shoot very well.

 

[Bullet]

SamTuckerMTNMAN

Reloading is my hobby and I’m no expert but I’ll add my 2 cents. I recommend that beginner reloaders stay with listed loads only using the same components as listed in the recipe. Changing components can or will make changes in pressure. Always reduce MAX powder charges by 10% and work up. I believe the data that probably will be the best for beginners to use is from the bullet manufacture of the brand and type bullet you choose to use. With this said your reloads might be under Max pressure and be perfectly safe to shoot even at 26.5grs. This is still confusing to me because I have no way to measure pressure and a lot of listed data is from test barrels, which are not the same as my rifle. Even data collected from a rifle just like mine will probably not be the same in my rifle. I load for my AR using VV N540 at powder charges that were listed below Max until VV’s newest data came out. Now I’m over Max using VV’s newest data. I haven’t had any problem with my reloads but when the data changes even from the powder manufactures sure makes me wonder what’s going on.

If I were you I’d stay with your 24.5gr load just to be safe and that’s probably where you would stay anyway since it shoots the best.

And by the way when I fired my first reloads, I had to change my pants and couldn’t sleep for 2 days.

Good luck, have fun reloading and be safe.

 

[hagar]

24.5 grains of whatever must be the magic AR load, because I load 24.5 of Varget, Accurate 2520 or RL15 for my 75 Hornady loads, and most highpower shooters use almost the same load.

 

[Highland Ranger]

And by the way when I fired my first reloads, I had to change my pants and couldn’t sleep for 2 days.

So you're having fun right?!

 

[Bullet]

So you're having fun right?!

Yes, I was kidding.

 

[gezzer]

Normal, brass will last for more shots also!

 

[DWARREN123]

So many variables, usually the max load is not the best. You will have to find which bullet, powder, primer and case works best and then find the best load combination.
That's what makes it fun.

 

[Shoney]

There appears to be two factors at work here. First as has been stated, your load of 24.5 is listed by Winchester as a max load. Exceeding this max load should be done only after you have a lot of experience reading pressure signs.

The second is your twist rate of 8. The 69 gr bullet is at or below the minimum weight to be stabilized satifactorily by this twist. When you push it faster, the instability is more pronounced.

Try a 75 gr bullet and heavier. Barrel maker Lilja lists the 80 gr bullet as ideal for the 8 twist.

 

[Bullet]

Shoney

The second is your twist rate of 8. The 69 gr bullet is at or below the minimum weight to be stabilized satifactorily by this twist. When you push it faster, the instability is more pronounced.

Try a 75 gr bullet and heavier. Barrel maker Lilja lists the 80 gr bullet as ideal for the 8 twist.

The heavier (longer) bullets need faster twists than the lighter (shorter) bullets to stabilize.
I believe the 1/8 twist will stabilize bullets 80gr or less. 69gr bullets should be fine. I believe the slower twists like 1/12 don’t have enough twist to stabilize bullets above 60grs.

From Lilja

“We offer a number of different twist rates in the various calibers that we make. This allows you to pick the optimum rate for the particular bullet you plan to use. This is especially true for target shooters who will probably use just one or two bullet weights and styles for their type of shooting sport.
However if you plan to shoot a variety of bullet weights in your barrel then you must choose the twist rate for the heaviest bullet that you plan to shoot. For example, let's say that you're going to build a 300 Winchester Magnum for longer range deer hunting. A bullet weight of 150 grains might be the best choice for your type of hunting. And a 12" twist would be correct for that bullet. But someday you might hunt elk or moose and think that you might want to use a 200 grain bullet for the bigger animals. Then the twist requirements change and a 10" rate is the choice. But, you can still shoot the lighter weight bullets in the 10" twist with good accuracy.
As bullet weights increase the twist rate required to adequately stabilize the bullet increases. The fact is though, that actual bullet weight has little to do with twist. It is overall bullet length that has the most influence on stability. The reason we base twist on weight lies with the fact that bullet length usually increases as weight increases. And some bullets are especially long for their weight. For example the Nosler Ballistic Tip bullets are all longer than comparable weight bullets of another weight because of the plastic tip. And as a result the ballistic Tip bullets sometimes need a faster twist rate than is normal.”

 

[toecutter]

There are several things at work here. As previously mentioned there are the barrel harmonics issues.

However, when you fire a bullet at slower speeds certain things like jacket imperfections, lead inconsistencies and other things are substantially less noticeable in flight. (think of a tire that's out of balance doing 50 vs 75).

I remember a while ago, one of the guys up at the range was reloading for his .458 win mag. He was nearly 10 grains over max (maybe more) The recoil was rediculous and he was complaining he couldn't get them to group... These loads were seriously painful. I told him to drop his charge by 15-20 grains and his groups tightened up and it was easy to plug a bowling pin at 200 yards with it.

The other thing is, with lighter loads there is less recoil. Also the recoil impulse changes a lot so you may not be throwing the gun into recoiling as quickly with the reduced loads.

All things to think about, but I think I agree with the sentiment, if you have a good load, don't mess with it!