Reloaded .223 velocity spreads

[rpm]

I'm reloading on a Dillon 550 with Dillon dies, Dillon powder baffle, Hodgdon CFE223, Lake City once-fired brass, CCI #41 primers and SMK and Nosler 69 grain bullets. My goal is to create a higher-quality reload, I have not yet had an opportunity to test for accuracy but I can do that after I work out the bugs.

Below is the test data I came up with last weekend using a Shooting Chrony F1 set up at 7 yards from the muzzle, temp in the low 50's

Nosler 69 grain, 24.5 grains CFE223
2564
2521
2511
2517
2539
2535
2450
2535
2508
2443

SMK 69 grain, 24.5 grains CFE223
2480
2467
2447
2497
2482
2492
2476
2505
2476

Nosler 69 grain, 25.5 grains CFE223
2621
2645
2669
2630
2616
2621
2636
2597
2569
2576

SMK 69 grain, 25.5 grains CFE223
2572
2575
2583
2591
2571
2647
2630
2579
2613
2572

I don't know if that is normal from a progressive press, but those seem like fairly large spreads in muzzle velocity to me. I test my powder throws multiple times during a reloading session on both a digital scale as well as a balance beam. I was going to bring some factory XM193 as a baseline but forgot. I have measured muzzle velocity with my pistol reloads and they are much more consistent. My brass prep is to tumble, lube, resize and deprime, tumble, swage and then load up. I do not trim cases (mostly because I don't own a trimmer) but I do own a Dillon case gauge I use to check before running them through. It has been suggested to me that the flash hole is inconsistent which may be causing the spreads, the cases I've inspected all look the same to me and I'm not really sure how that would affect velocity, then again, I'm new to rifle reloading.

I've tested muzzle velocity previously on a borrowed chronograph with a previous batch of 55 grain reloads with similar results - as it was plinking ammo and accurate enough for carbine work, I didn't get in a twist over it.

So I guess my question is, is this normal? If not what can I do to tighten the range up a bit short of hand loading on a single stage press?

[spleify]

So I guess my question is, is this normal?


Yes...but..I'll explain



what can I do to tighten the range up a bit short of hand loading on a single stage press?


Ok, this is going to the long and short of it

This is very common to see such a big spread as you have many different variables working against you. You mention that you double check you powder throws so we know that is a confirmed point. Now other variables to take into account, and in no particular order.

Weight of cases. Cases are going to weigh different amounts, in part this can create different pressures because likely the inside case volume is different. The smaller the inside diameter the higher the pressure could potentially be, the bigger the inside diameter the higher the pressure.

Flash holes. Flash holes will be different sizes, though they may not appear very different to our eye there is a difference and you can ream all of your flash holes so they are the same size and remove that variable. This effects the speed at which the flash from your cap will ignite the powder in the case.

Trim length. Trimming all of the cases to the same length will lend itself very helpful when trying to tighten groups. With all of the cases being varying lengths you will get different inside seating depths of your bullet in turn creating different pressures. The farther in the bullet is seated the more pressure it could potentially create, to the flip side the farther out the bullet will also alter the pressures by potentially lowering them.

Bullet seating. you simply can not really accurately seat all bullets to the same length if you are not trimming your cases. Measuring the COAL(Cartridge Over All Length) will give you a fairly accurate measurement but to get "true" COAL measurements you should be measuring with an ogive gauge.

Powder charge. Powder charge is very very important. The correct powder charge is going to be paramount in gaining accuracy and tightening groups. I'll explain more below.

Crimp. crimping the mouth to the same size on all your loaded cartridges is important so you can increase your chances of consistent inner gas pressures. Too loose a crimp you can lower your pressures, to tight a crimp and you increase pressures.

These are a few of the steps to accurate hand loading. You will get varying results on any progressive, no matter how good it is. True marksman or bench rest shooters will load one round at a time and only on a single stage press. This is merely a 30,000 foot view of accurate hand loading but a few things for you to research more. And only one mans "opinion and method" so do your own research and I am by no means saying this is the only way to do it. If you ask 10 more people you will get 12 more opinions on how to hand load.

Now, with all of that being said, IME if you are also looking for accurate, tight groups you are going about it backwards. Unless you main objective with load testing and speed is to get a super hot round so you can say you are shooting at 3300fps or something like that I am not so concerned with speed in my early testing for a new load for a particular rifle. I will load up usually 15 rounds of a certain load with a certain amount of powder and a particular projectile that was chosen by research and others's success. ie, when I was working up my .308 round I knew I was going to start at 44gr of Varget behind a 168gr SMK. I loaded 15 rounds each of 44.0, 44.1, 44.2, 44.3 so on and so forth all the way up to 44.9, I shoot three, 5 round groups Take accurate measurements and then I choose whichever load shot the most accurate groups on average. I document and save ALL previous data so I can go back and refer to things if I have questions. After you have found an "accurate" load you can start to fine tune things. NOW you want to know what speed your shooting so you can obtain accurate DOPE.

Now, this is only the the loading process, we didnt talk about the firearm itself, the trigger, the stock(or chasis), the barrel, or the shooter, or the environment, or the way the shooter approaches the scope and rifle before every shot.....etc. bottom line is there are a number of variables to accurate shooting but that is what makes it fun. Enjoy yourself and work on one or two things at a time. Dont try and change 5 or 6 things at once because you wont really know what is helping or hurting.

Take it slow and have fun brother.

[<MADDOG>]

+1 to above, just add powder to the list.

By the way, how did your second load shoot?

[rpm]

Awesome, spleify! A lot of excellent advice, thank you!

[IceAxe]

+1 to all the above, and add neck tension.

both the varying thickness and hardness of the brass in the neck can effect ignition pressures and therefore velocities.

[spleify]

Great points maddog and Ice, i did add those to the above post

[Awesom]

[Hoser]

Check for accuracy first, then put it over a chrono.

If it is accurate, velocity spreads dont matter at short ranges.

If you want to make your powder throws more consistent, spend some time polishing the inside and moving parts of your powder measure.

[SA Friday]

Yep, if you are shooting 1/4" groups, the velocity spread doesn't mean crap.

With that said, not trimming the necks and not reaming the inside of the flash hole will effect your rounds. As mentioned the variation in neck length changes the amount of tension against the bullets. LC primer holes are punched and many will have flared out pieces of brass that can cause the powder to ignite and burn inconsistently in the case. If you want accuracy, these two factors will effect velocity and accuracy. Match grade ammo means weighting every powder throw and prepping every piece of brass for the absolute least amount of deviation.

You also have to account for the accuracy of your chronograph and inconsistencies based on your light source. Intermittent cloud cover can cause problems sometimes.

[Zombie Steve]

I know I'm late to the party, but I just wanted to make sure of something:


My brass prep is to tumble, lube, resize and deprime, tumble, swage and then load up. I do not trim cases (mostly because I don't own a trimmer) but I do own a Dillon case gauge I use to check before running them through.

If you're checking them before running them through, you're wasting your time. You measure / gauge after the case gets sized. That's where any stretching occurs.

Get a trimmer.




Also - I haven't used CFE 223 and I'm not looking at any load data right now (nor do I know your barrel length), but it's a fairly slow powder for 223... somewhere in the Varget - BL-C(2) range, anyway. Typically slower powders are going to exhibit a little more consistency on the upper half of the load data. Not to say that's the most accurate at short range, but more consistent over a chrono.

Again, I don't know where you were with those loads, but if you were on the low-mid range of the data, keep working up. I bet you'll have a "ta-da!" moment.

Last but not least, you did two tests with each bullet, and it was about a 2.5% jump. I'll generally work up in 1% increments. Little safer, and you're less likely to miss the sweet spot.

Keep at it. Let us know how it turns out. It's pretty cool when you see a 1 digit extreme spread come up on the chrono.

[spqrzilla]

There are some great articles in back issues of Handloader that show that variation in powder charges is probably the least significant of all the variations that affect accuracy. And the proof of an accuracy load is holes in paper - not chrono readings.

Frankly, I don't find those velocity readings that post all that "bad" in variation. Don't forget that the chronograph itself has an error range.

I think every reloader needs a chronograph and should use it. But what I'm looking for are odd behaviors in the velocity like unexplained higher or lower average velocity than I expected. I'm using it more as an indirect measure of pressure behavior than worrying about relatively small variations.

[Zombie Steve]

Some good advice, there.