I use the RCBS Rockchucker and RCBS or Redding dies. I trim once-fired brass to length and measure the brass to make sure all are the same length. I get the seater die giving me a cartridge of the overall length I want, say 3.330 on a .300 Win Mag. But the resulting cartridges frequently vary in overall length by 2 to 5 thousandths--maybe it's immaterial, but it bugs me and I don't know why. I have the seater die locked down good and tight. Any ideas/suggestions? Thanks.

Swampcat:

the total OAL and the EFFECTIVE OAL are different. the total is affected by bullet tip deformation, differences in ogive shape and point of strike.

the effective OAL is the distance from the lands to the bullet. which is on the shoulders.

should be close with good bullets, and within one batch of bullets.
at times I have also had compressed loads try to spring back a thousandth or two..

also check your lower unit for sound hold on the case base. sometimes some grit, sizing lube, or other obstruction affects how the brasss is seated in the holder. should be some play buy not much.


check your

Measure your bare bullets over the nose. You will find they vary in length. Most of the variation is at the tip. Your seater does not touch the end of the bullet but touches the nose down about 3/16.
This causes a variation in the loaded length even though the die does not change.

So, how much does this difference in OAL affect accuracy. I have the same problem. Is it more important to keep the case capacity constant or the bullet jump constant?

quote:

Originally posted by Swampcat:
I use the RCBS Rockchucker and RCBS or Redding dies. great tools!

I trim once-fired brass to length and measure the brass to make sure all are the same length. I get the seater die giving me a cartridge of the overall length I want, say 3.330 on a .300 Win Mag. But the resulting cartridges frequently vary in overall length by 2 to 5 thousandths-- maybe it's immaterial, but it bugs me and I don't know why.get over it.....that's normal

I have the seater die locked down good and tight. Any ideas/suggestions? Thanks.

A lot of reloaders get to measuring things that are irrelevant. Such things like wanting the case lengths to be all exactly the same.....criminy.....a .005 variance is not bad at all!!!!

Some get carried away with runout.....another losing proposition.

COAL is just another worthless thing to try to control to exact measurements.....

I read about guys measuring powder to the nearest .1 grain all the time....loading 60 grains of powder and needing .1 accuracy....?

Some guys get upset when their chronograph tells them that their standard deviation is xx feet/sec.....

Hey guys.....get out there and measure groups at the range.....use a tape measure if you have to,.....it's the only measurement that counts... and don't think it always needs to be 1/2" or less.....most of them groups were never fired except on the internet!

What Vapodog said gets a big +1. We weigh and measure many things now simply because we can. Before electronic scales came along,(for instance) few if any folks (except Bench Shooters MAYBE) weighed their brass or bullets. Now I routinely read about guys making hunting ammo wanting to know how small a segregation to use in making their case seperations. And they are doing a case prep that would do a Bench Shooter proud BEFORE they ever fire the first shot.
I'd much rather fire cull my brass at the range, thank you very much.

I am using Barnes TSX bullets, so I don't think bullet deformation is an issue. It was with soft points, but not now. I am not sure that the problem is manufacturing variations, either but I will measure a batch over the nose and see what I find. Good suggestion. The "get over it" and "you don't need to shoot 1/2" groups" answers are unresponsive. They don't contend that precisely matched bullets won't group better--and they certainly should. That reply is like the car dealer telling you "they all do that" when you take the car in with a problem. Each of us has his own standards. I want bullets built as nearly alike as the equipment I have permits.

Hey Swampcat, Try converting from OCL to ODL, have a consistent Seating Stroke and have confidence in the Die.

Only real problem (which should be in the Link) is if the Bullet Tips are touching the Seating Plug - instead of the Bullet Ogive touching the Seating Plug. The Accuracy Key to Consistency in this situation is not having the OCL the same on each Cartridge, the Key is having the Ogive the exact same distance from the beginning of the Lands.
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quote:

Originally whammed in by 303Guy:
...Is it more important to keep the case capacity constant or the bullet jump constant?

Bof'um! (Both of them - for the YANKEES!)

Consistent Accuracy is not created by taking short-cuts or doing things half way. No doubt a Reloader DOES NOT need to do all the Accuracy Tricks to "luck into" a good Load. In the long run though, doing all the small things correctly adds a bit in the positive direction for each segment and they eventually add up to FREE BBQ Suppers.

Thanks, Hot Core. I'll check that.

Au Contair Mr Swampman, the answers of get over it and you don't need to shoot .5" were as responsive and as valid as any of the others. They just weren't what you wanted to hear.

Don't assume that dicking around in the shop trying to create some sort of perfect cartridge is any sort of moral high road over the fellow that is out on the range learning how to shoot even if his ammo is less than perfect.
If you are shooting a factory rifle, the manufacturing tolerances are suficient to make a 5 thousandths variance in cartridge length conpletely insignificant.

Have you tried grouping your cartridges into lots that were exactly the same length and lots that were widely divergent to see if there was a measurable difference in accuracy?

quote:

I'd much rather fire cull my brass at the range, thank you very much.

Hey now, there's and idea! Thanks for the tip!

quote:

... and don't think it always needs to be 1/2" or less.....

I know it doesn't need to be, but .....

quote:

Have you tried grouping your cartridges into lots that were exactly the same length and lots that were widely divergent to see if there was a measurable difference in accuracy?

Hey, this is serious in a fun sort of way. I would be interested in the results. (Remember, I have the same sort of problem). I have set of ammo I have made up which is sorted into bullet weight and case weight.

Stillbeeman--I think you better look up the word "responsive." When I ask for suggestions for lessening/eliminating cartridge variations, a reply that says I don't need to is unresponsive in my book--and I think you'd say the same if you got that kind of flip answer to a question you asked. Not a question of whether I like the reply or not--it simply does not answer the question I asked. Nor have I suggested that handloading puts me on some moral high ground. You conjured that absurdity up on your own. As for spending time at the range, I am there several hours every week. How about you? And have you tried the experiment you suggest? If so, let's have the results--with details.

Since I belong to a very exclusive shooting club with a very select membership of one and a few well chosen guest, and since that range is located right outside of my reloading shop, I think it is safe to say I spend a few more than several hours a week at the range on an average.

I'm not a Bench Shooter but I do compete in Factory Matches. And often win. Rarely do I not place. My smallest ever group in competition has been a (as in single) .111 5 shot group. Not too shabby for a box gun.

Responsive: root word, respond: to react.

quote:

Originally posted by stillbeeman:
... My smallest ever group in competition has been a (as in single) .111 5 shot group. Not too shabby for a box gun....

Darn shame you didn't have your Cases Fully Prepped and kept a close eye on the Seating Depth, it might have been a Bragger size group.

That ain't nuthin compared to some of the ones where I get to "estimate" the size or quote cyberspace measurements.
I've even had some 5 shot groups that were so small they didn't even make a hole in the target.

To calm things down for a moment, Swampcat. I agree with Hot Core to the extent that everyone should KNOW the various techniques of hyper accuracy; however, it is a field of extremely diminishing returns. And when one is working with a hunting bullet and a sporter rifle, many of the facets of ultra accuracy are truly a case of no returns rather than diminishing returns. Case in point: when I was using a 7-08 in Factory Matches, I used neck turned brass. I certainly don't use neck turned brass for my 7-08 hunting ammo. I also used match bullets in a match and hunting bullets whilst hunting. This is what Vapodog and I tried to point out to keep you from spending a lot of frustating time chasing your tail. You choose to take offense.
Hot Core pointed out that the OAL of the cartridge means very little; it is the distance from the shoulders of the bullet to the lands that CAN be critical. So that is a learning point. Will it be useful with a hunting bullet and a sporter rifle? That is another thing that can be debated. Thus my suggestion of the test.
Often some of the best information is empirical knowledge that comes from doing rather than getting second handed information. In this case, the knowledge would be first hand reality rather than abstract theory. One of the challenges of reloading is finding what YOUR rifle likes as it is an individual.

The bullets nose profile can vary as much as 0.002". It will not matter to you accuracy unless you rifle is as capable as stillbeeman's.

quote:

Originally posted by 303Guy:

quote:

Have you tried grouping your cartridges into lots that were exactly the same length and lots that were widely divergent to see if there was a measurable difference in accuracy?

Hey, this is serious in a fun sort of way. I would be interested in the results. (

Sometimes what seem to be absurd measurements can be really helpful.

As you folks may or may not know, the Brit hi-power team is easily one of the best in the world. It wins the Palma Match FAR MORE THAN AT LEAST its share of the time, and frequently wins the more important team matches in the National Tournaments of other individual countries as well.

One of their secrets for assuring the best possible results in matches and countries where all teams are required to fire military 7.62 Nato ammo issued at the firing line is to quickly weigh each individual round of ammo.

That particularly worked well for them back as long ago as the end of the '70s and beginning of the '80s, when both rifles and ammo were issued by drawing lots at the Palma Matches. It was one of the few "advantages" a team could legally take over its competitors, if they thought ahead to do so.

The Brits then separated their ammo by weight into various lots. Each lot was fired as a lot, that is with no other weights of ammo from other lots mixed in. Their results with that, as proved both by documented experimentation and match results, was that it WAS worth their time to do.

Based on that same approach, many of the "benchrester" techniques which have developed over the years are also useful.

Benchresters have found by competition that some common loading techniques are not useful, such as weighing small charges of powder used at short range (up through 200 yards), but other less common ones, such as seating primers by feel rather than to a particular seating depth, or deburring the inside the case end of primer flash holes, ARE worthwhile when seeking best acuracy.

In my opinion, the more fragile the bullet, the greater the benefit of making the proximity to the rifling lands uniform.


Added for Swampcat- the deformation is still there in Barnes bullets. It is not post-manufacture deformation...it is the differences in dimension which are part of the manufacturing process. If you get something like a Sinclair bullet comparator attachment for your dial caliper, you can easily measure the variation from the bottoms of the bases to the point where the bullets actually touch the lands. You don't NEED to for good hunting ammo, but the nformation is sometimes rather interesting (and shocking),depending on the bullet maker.

quote:

Originally posted by stillbeeman:
...I've even had some 5 shot groups that were so small they didn't even make a hole in the target. ...

I had a 1st Generation 7mmRemMag M77 Ruger that would occasionally make a Bragger 2-shot group(same with the current M700 in the same caliber).

Had gone to the Range with a buddy and his nephew to shoot one day. The nephew loaded 9mm mags all the way (1hr 15min) to the Range and had them empty in just about 15min. Anyway, he was a bit bored for the remaining 10hrs we were there.

As we were finishing shooting I had 2-shots left for the old 7mmRemMag and the 2nd shot cut into the first shot. We all walked down and looked at the Targets. Of course, I was pleasantly SURPRISED at the 2-shot group and the nephwe was about to have a fit to buy the rifle.

I looked them both straight in the eyes and said, "If you want it that bad, I will sell it to you - BUT - you must promise me that you will only shoot 2-shot Groups!" Of coures he asked, "WHY?" Told him, "The rifle shoots so tight that a 3rd shot will completely close the hole in the paper."

quote:

Originally posted by Hot Core:
"The rifle shoots so tight that a 3rd shot will completely close the hole in the paper."

Hey HC

I know exactly what you're talking about, here's one of my targets, the hole is almost gone




On a serious note, I think it is not as important how far you are off the lands within reason, as it is that all your bullets are seated to the exact same length. Case in point I was looking for a distance to seat bullets and did a ladder test of seating depths. Notice the difference in point of impact at the different seating depths





These were all seated with a Redding Competition Seating Die and each was checked with a comparator.

woods, that is seriously interesting!

I made a 'slight' booboo with my loading last night and found a rather interesting result today. I got the seating depth wrong. Too deep. The result was rather startling (to me anyway). The rifle recoiled! (We are talking hornet here). I lost the sight picture and did not see the bullet strike. Penetration through a tree trunk was notably better. Then of all surprises, the barrel did not heat up! Usually it gets quite hot very quickly. Primers were more flattened and I will not be firing the rest of that batch. But less recoil with a suppressor can only mean more powder energy has gone into the bullet. Oh yes, the bullet had a sharper 'crack'. Go figure.