Accuracy tweaks


#1

Still consider myself a reloading noob but had good success with handgun loads for practice.
I’m soon going to start reloading some rifle calibers and have a question.
Many of you take pride in tweaking loads for accuracy.
What I don’t know is other than powder type and charge what other tweaks do you use?
Obviously choice of bullet I imagine but are there other tweaks? Bullet seating or crimp tweaks.
Any pointers welcome.


#2

Primers can make a difference. Some have a stronger charge so thereby have better ignition. Powder burn rate that matches the barrel length is good. Too fast or too slow will effect the end result. Having a chronograph is a big plus to ensure stable velocities. A good bench rest also helps a lot. You want good grouping. Too fast or too slow well effect that accuracy.


#3

Oh ya, type of bullet is important. Standard bullet, boattail, rebatted boat tail, the Ogive of the bullet. You’re in a whole new world here.


#4

Yeah I appreciate that this is a new world here and you’ve brought up some good points.
So burn rate… what’s the correlation between burn rate barrel length? And does twist rate factor in?

And (fully admitting ignorance here) I give… what is Ogive?

Any books on this science?


#5

On rifles I like to seat the bullet where it is just touching the rifling . That meens it dosnt jump between the case and rifling .


#6

Absolutly. For precision rifle, The longer you can leave the bullet hang out, the better!


#7

research powder load for the distances you intend to shoot. Also using full lead bullets will make your barrel last forever.


#8

Welcome to the wonderful world of accuracy loading @mquinn55 ! Allow me to ramble on.There are may things that can be used to squeeze out a little accuracy. As stated, one of the considerations is use the right bullet for the distance you will shoot.
**PLEASE NOTE THAT I LOAD FOR BOLT GUNS THAT ARE SINGLE FED. YOU SHOULD I DO NOT CRIMP, BUT IT IS RECOMMENDED FOR GAS GUNS. ** Adjusting crimp… or adding one… can also improve accuracy, tho I don’t need it, so i do not use it.
If you are shooting within 200 meters, a flat base bullet will work well and there is no need for the boat tail. 69 grain will shine here. When you get into 3-600 you are looking for something heavier if your barrel twist will allow for it. Basically the heavier the better. 77 grain, 80, 80.5, 82, and 90 grainers will be your friend because of the higher B.C. and less wind drift. I have had to hold off as much at 5 moa at 600 with the 82 grain bergers…imagine what a 69 or lighter would have done ;).
OK. So my suggestions:

  1. Pick a bullet mfg. If it isn’t berger, check the wight on a scale. This sucks… so if you don’t want to do that, just load in lots of 100. Sort each box separately as base to ogive measurements and well as weight may be different between lots, but also between boxes in the SAME lot! I had issues with sierra in regards to this,. That is why I switched to berger… I just don’t want to sort them anymore. IN GENERAL, TRY TO KEEP YOUR POWDER AND BULLET LOTS SEPARATE.

  2. Buy a powder trickler. They are cheap. It will ensure a very accurate powder charge every time. I use the chargemaster and redding trickler. If I wasnt 23.3 gn, I set the chargemaster to charger 23.0 gn… then trickle the rest. I noticed a slight drop in velocity Standard deviation values when doing this.

  3. If it is a bolt gun, you don’t need to full lengh size! You need to size the neck AND bump the shoulder, but the body of the case can be left as is and loaded in that specific chamber many more times than if you were to full body size it. This leads to #4.

  4. Forster sizing die. 2 Things this bushing die will do. It will allow you to set neck tension in .001" increments with bushings, and will bump the shoulder back to make sure the brass doesn’t grow and make an unsafe shooting condition. I can expand on this if you want. Its just a way of keeping the brass from having to move as much and leads to longer brass life and less standard deviation ( I dropped 20fps of deviation by setting neck tension to -.002. Test done with 100 rounds)

  5. Setting your bullet seating depth: Use a comparator to measure your overall length off the ogive, not calipers from the tip. Look up COL gauges. Basically you use them to find the lands for your rifle so you know when you will kiss them, and then seat the bullet using that number as a reference. I usually start with the ogive .020" from the lands. After getting a load I like, I move it out in .005" increments until I touch the rifling. This creates the safest condition because the pressure will drop as case volume increases. This is why I do it this way.

  6. Primers. Pick a few and see witch are the most accurate for your combination early on. This is best done mid range between min and max load data/ velocities because the primers could increase or decrease velocity and most importantly pressure. Small groups do not matter as much here. Lets say you know you are safe at a certain powder charge. Load 10 rounds of lets say 3 primers. In my case it was cci BR cci 400 and rem 7 1/2 primers. I found that my groups were large ( 1" about) at my current charge weight. Rem shot at 1.25" and had very high SD in velocity, BR shot better but with a higher SD, cci 400 shot .850 inches and SD was lowest. So I chose the cci 400 primers and then started my real load development after I chose. This worked well for me.

  7. Uniform your primer pockets and flash holes. Flash holes are a hit of miss, and may only really play a roll in longer distances. I did find my SD dropped slightly uniforming, so I always do it. Primer pockets should be an equal depth and square at the bottom. This will help get rid of shot to shot inconsistencies. This goes hand in hand with hand priming. You push the primer in until you feel it kiss the bottom of the pocket then stop. Keeps the primers from crushing, causing more variation.

There are more… but this is getting long. I think the most important “tweak” is to chrono your data and find where your “accuracy node” is and marry it to that velocity. 2750 may be where your load shoots best. But if you develop the load in summer in 85 degree weather, it could drop to 2625 in 10 degree weather. Shoot in all conditions! Match your velocity, and document this charge weight so you know it for future reference. I recommend the magneto v2 chrono as it will not be affected by lights and weather.

If you need clarification or photos… even a video, just ask and I’ll do my best to help!


#9

Ogive is the portion of the bullet that will actually make ontact with your rifling. That is why this measurement off the ogive is so critical.


#10

Appreciate the detailed response. It’ll take me a while consume but very helpful I’m sure.


#11

No problem. Its a lot. I was going to go into detail, but then it would be a book. Hope i highlighted the concepts and if they interest you, there are a lot of videos out there that will better explain in detail.


#12

Get several reloading books from places like serria hornaty berger speer hodgen. Look at them all and you can get some that give step by step instrutions .


#13

Looks like your questions got answered before I got back home.

Ease in to it, there’s a LOT to learn. I finished up a 8 week introduction to ballistics last quarter in my collage course, and will have advanced ballistics coming up. Digest what has been said and move on from there. Start out with basic loads to get the hang of things, then tweak things for more accuracy. Look at the min - max loads for the bullet you’re using and start around 60% and ease up.


#14

But wait there is more!

Neck turning (inside vs. outside) and measuring. Bump sizing (in between new only and full length) in .002" increments. Decapping and neck sizing in separate steps. Run-out measuring and reducing.

Being consistent will get you 95%. But that last 5% is more work. And then that last 0.1% is what separates 1st place from 2nd place.

There are some things I will do for hunting (including long-range varminting) and others are just not worth it to me. Target shooting is another story.


#15

Damn spell check. That should say : “in between neck only and full length” for the bump sizing.