View Full Version : Bullet weight variation and accuracy

04-24-2014, 10:47 AM
Good Morning!

I have a question regarding accuracy and bullet weight variation:What are acceptable bullet weight tolerances?

For example, last night I cast about 175 bullets for my 40 S&W. The mold is the Lee 175 gr. SWC. The bullets came form the mold at 185 gr. +/-. I set a range of 1.5 grains +/- as my acceptable weight. So, anything between 183.5 and 186.5 was a keeper. I weighted each bullet on an electronic scale.

This was after each bullet had been inspected three times. 1. As they come out of the mold. 2. After they have cooled. 3. And after the Lee Liquid Alox has dried. The dried Alox brings out detail I don't see when the bullets are nice and shiny. Any defective bullet is rejected and tossed back in the pot.

If my math is correct, 1.5 grains +/- 185 grains is a variation of 8/1000 +/-. It is possible that I could fire a round with the bullet weighing 183.5 grains and the next one could weight 186.5 grains.

The rounds are coming out of an "off the shelf Ruger SR at a range of about 10 yards. I don't think the variation of 1.5 grains +/- makes that much difference. But I would like to know what you think.

I set more stringent weight requirements when it comes to rifle bullets. For example, I made 150 .30 cal. bullets for my brother-in law. Since he insisted on paying for them, I set a range of only .5 grains. This was with the Lee c309-200R mould. The bullets fell from the mould at 195 grains. So, anything between 194.5 and 195.5 was a keeper. Fortunately for me, the planets were in the right alignment and fortune was smiling on me. Most were very close to 195 :grin: He was happy with them.

Controlling variables leads to increased accuracy. To sum up: What are acceptable bullet weight tolerances?

Thank you all for reading this and for your comments.


gray wolf
04-24-2014, 11:28 AM
You need to sit back and relax a tiny bit. Not that what your doing is wrong, just that IMHO your way over thinking the variation.

off the shelf Ruger SR at a range of about 10 yards. I don't think the variation of 1.5 grains +/- makes that much difference. But I would like to know what you think.
At 10 yards or 15 yards I don't think you will ever notice a difference in your shooting, even with a 3 or 4 grain spread. If you do I would like to see it, shooting off a sand bag included.
For serious rifle shooting I think you will find a difference of opinion with everyone setting there own standard for what they expect and what they want to achieve.
IMHO I also think your bullet sorting may be a tad over the top for what your shooting.
Yes wide spread variables do tend to induce errors at times, but we have to understand at what point and and what variables need to be pulled in for what calibers we are shooting, including our expectations.

Now please understand I am in no way condoning being sloppy or careless with what you/we do. Far from it,
in fact I commend you for wanting to do things to the best of your abilities But sometimes our efforts are better spent at a different aspect of the proses.

What you may find interesting is to take a batch of bullets and carry on with your method, then take some and sort them in what you may call sub standard bullets in different categories, shoot them and see what your results are. At that point you will have established in YOUR mind what works for you.
To repeat myself; Rifle bullets can require there own set of standards, in order to match up with the shooters
exceptable standards.

04-24-2014, 11:59 AM
At 10 yards, I would shoot almost anything that is filled out. There is no need to weigh.

One thing to consider - do not inspect the bullets as you mold them. It will upset your cadence and result in more rejects. Find the speed your mold/alloy wants and just cast. You will likely need to reject the first 10-20 pours but after that, just cast. Leave any inspection for later. But again, do not worry about anything except obvious visual defects for your pistol rounds.

I used to weigh bullets used for 50 yard Bullseye and used a +/- .2 grain tolerance on 148 gr bullets. These were for matches only. All practice bullets were cast, lubed/sized and loaded.

Rifle bullets again depend on use. For plinking ammo, there is little need to weigh if you have a consistent casting routine. For group shooting it will depend on the bullet. 60 gr bullets need a tighter tolerance than 200 grain bullets.

Don Verna

04-24-2014, 12:21 PM
I know weight variation matters, but will I ever see it? I'm just not a MOA shooter. It's either me or ALL my guns.:mrgreen: I'd like to know if a little weight variation is something that turns a 1" group into a 1-1/8" group or if it's something that turns a 1" group into a 4" group.

04-24-2014, 04:18 PM
Mike--As others have said for your .40 S&W @10-20 yds your QC is unnecessary. Even for 25 yd shooting with stock auto's all I would look at would be the bullet bases as I open the mold and any really obvious defect. Beyond that I would spend my time dry firing, practicing trigger control and sight alignment. It sounds like you have the casting process down pretty well.

04-24-2014, 04:22 PM
The effort is commended but not necessary for stated purposes

04-24-2014, 04:59 PM
Anything that ends up within 1% - 1.5% has got to be close enough. We're not launching interstellar probes. You're doing fine.

04-24-2014, 07:40 PM
Anything that ends up within 1% - 1.5% has got to be close enough. We're not launching interstellar probes. You're doing fine.

Totally agree. Life got much simpler when I stopped weighing pistol boolits....and I never noticed the difference at the target.

Old Caster
04-24-2014, 09:40 PM
I shoot a lot of Bullseye at 50 yards with a 200 grain Saeco 069 and I never weigh the bullets for that. I do however have a lot of confidence in my casting ability and the quality of the mold so I usually have no rejects unless I immediately catch it. Once in a great while I will catch one with a base not as square as I would like when lubing.

I also shoot steel plate challenge and use a 6 cavity Lee bullet. The mold quality is not as good but it certainly doesn't make any difference for this discipline which is shot out to 25 yards with the target being a man sized steel silhouette. Unless it looks like the bullet won't stay in the case correctly or the nose somehow is real crooked, I will load and shoot it.

When I shot BPCR I would make enough bullets so that I would have 15 in each group that were within one tenth of a grain and all the groups would have to be within 1 grain and be in the center of all cast. Just because you have 15 of a certain weight doesn't mean they are a good 15 unless they are in the middle of the bunch. Each time a different target was shot at, (range of 200m to 550m the gun would be sighted in again at that range and the 5 bullets would do that with no problem with 10 left for the target. Left overs were used in practice. Whether this all made a difference is debatable but it wasn't worth the enormous effort to prove or disprove whether it did. I only ladle cast those out of a Waage pot and that pot was incredible about keeping the temperature exactly the same all through the event so my variations were very minimal with all that attention.

The bottom line is how far are you shooting, how careful are you aiming each shot and what kind of gun are you using.

04-25-2014, 06:18 AM
For pistol rounds I inspect the base and the driving bands. I do not accept any visible flaws back of the driving band. I am more tolerant of minor flaws on the nose area. I have no idea of the weight variations for pistol ammo.
If I also have a rifle in that caliber I set aside any with a nose lacking any visible flaws and save them for the rifle. I don't shoot competition except with myself .

I have no problems with a squirrel head at fifty yards that i can blame on the ammunition.

04-25-2014, 07:53 AM
I never weigh boolits, tried it too many times with sometimes worse results anyway.
What I did find with my 30-30 was run out, traced to uneven necks so I turned them just enough to make them even. That took me down to .002" or less run out.
Then I weighed the brass to find a vast amount of differences.
Now I have shot many 1" and less groups at 100 yards with my revolvers and used to shoot to 500 meters (547 yards) and hit steel. I can't do that with my BPCR! I do not weigh revolver boolits. But I worked my tail off with the BPCR and still don't know what the Browning wants.
Unless I was shooting a .22 or small caliber rifle, I don't think weighing boolits is important.

04-25-2014, 08:10 AM
I am very OCD about my bullets as well .. so to convince myself as to what was needed I ran all kinds of group tests. End result was
for pistol bullets less that 30 yds no sorting for weights .. it made no discernible difference to sort
50 to 100 yds (I shoot several caliber contenders) 1 grain difference

Rifles.. 50 to 100 yds 1 grain.... if just plinking rds no sort
rifles and pistols ..200 and further usually stick to .5 grains and for competitions .2

life is simpler now and I know the differences or lack thereof it makes

04-25-2014, 03:16 PM
IMO, weight variation really doesn't matter under 50ft with handgun bullets. I can shoot 200gr or 230gr into the same 2" hole out to 25yds. Out at 50yds, wt changes in bullets start to show up, certainly out to 100yds. So I only weigh my hunting or long range handgun bullets. Good bases are more important IMO. Final base check is during sizing, if it's flawed, back into the pot.

05-06-2014, 09:52 AM
Good Morning Gentleman!

Thank you all for your comments. I will relax my QC for my pistol. Shooting them is a lot more fun than casting and loading. I'm going to continue to keep to stringent QC requirements for my 7mm-08. My job for 19 years (prison chaplain) required some OCD. Situational awareness, key control, etc. I don't believe I will ever give that up. It became pretty ingrained.

It is a sunny day here in Michigan. I may head out to the range.