Ideas to improve consistency of Base-to-ogive (BTO) for handgun loads, for performance and safety

[Jim Watson]

Right, same as the conventional single shellholder standardized long ago by Pacific.

 

[JimGnitecki]

The red area is where a rifle or pistol die will make contact. The distance from the platform to the red area should be close to .125" View attachment 1105627

The shell plate can be placed on any flat surface to measure each station.

Let's clarify: "Platform" is ambiguous to me. When you say the distance from the "platform" to the red area should be close to .125", do you mean the distance from:
- the top of the shell plate, or
- the bottom of the shellplate, or
- the top of the frame surface that the shell plate rotates upon?

Jim G

 

[243winxb]

This

the top of the frame surface that the shell plate rotates upon?

Part 13781 Shellplate Platform on 550. The platform is bolted to the Main Shaft/ ram.

 

[243winxb]

Brass is most important for accuracy.
For 45acp, i buy 500 new Starline and keep them is the same rotation. All fired & reloaded the same.

If using range brass, accuracy may not be as good.

I did test 5 different brands for bullet pull/neck tension. To move the bullets, it can run fron 45 lbs to over 100 lbs. This much difference cant be good for accuracy. (Not tested)

 

[JimGnitecki]

This


Part 13781 Shellplate Platform on 550. View attachment 1105632 The platform is bolted to the Main Shaft/ ram.

Thank-you! That makes it clear what we are measuring.

Jim G

 

[JimGnitecki]

Brass is most important for accuracy.
For 45acp, i buy 500 new Starline and keep them is the same rotation. All fired & reloaded the same.

If using range brass, accuracy may not be as good.

I did test 5 different brands for bullet pull/neck tension. To move the bullets, it can run fron 45 lbs to over 100 lbs. This much difference cant be good for accuracy. (Not tested)

Noted, and agree. I also wonder if the tumbling media and additives, particularly the additives, make a difference to the amount of force needed to move the bullets in the finished cartridges, and if using an additive in tumbling, and doing so consistently and at the same "concentration", can possibly help to reduce the variances in friction from case to case? IF it does, that's another step we can take to improve consistency of our loaded rounds.

Jim G

 

[lordpaxman]

I’m just tagging in to see what everyone’s saying. Personally I’m still a COL person (and not a COAL person). All published load data that I’ve seen is in COL terms, not CBTO - BTW, BTO is a group. I’m more interested in if there’s really measurable precision or accuracy increases in pistol rounds. I am a proponent of consistency, including COL or CBTO, but there are a lot of variables in reloaded rounds and for short range competition loads I’m not sure it’s worth chasing a thou or two. Especially after the buzzer goes off.

 

[jmorris]

I’m more interested in if there’s really measurable precision or accuracy increases in pistol rounds. I am a proponent of consistency, including COL or CBTO, but there are a lot of variables in reloaded rounds and for short range competition loads I’m not sure it’s worth chasing a thou or two.

Well, that’s easy and you don’t even need equipment that makes everything perfectly the same. You just need a large enough sample of loaded ammunition to sort a bunch of “perfect” rounds from the various +/- ones.

Now you can take the “best” pile and “worst” pile and shoot them side by side with the same firearm, a machine rest will take you and your feelings out of the test.

At this point you can quantify by the two group diameters, the gains (if any) perfect ammunition give you over +/- however many thousandths your setup delivers.

If you can’t tell any difference, or it’s insignificant to you, there would be no need to change what you are already have/are doing.

Is it worth it, for short range competition like USPSA/IDPA? Not until it does, I have won lots of matches with ammunition loaded to meet goals other than ultimate accuracy. Also, have lost by some very close margins, that would have flipped the results in my favor if a single shot had been in the next advantageous position. Rare to be that close to the next competitor but it does happen. That said, there is generally a time component to those games that gives you many more areas to get out in front of fellow competitors that could be better time spent.

That’s said, sometimes it’s nice to know either way what results the extra effort will give you.

 

[JimGnitecki]

Ok, I want to "bore out" the seating insert on my 9mm Redding Competition die.

The objective is to prevent any contact of the inside of the seater insert with either the bullet meplat or ogive, except at just ONE point: The very bottom "rim" of the seater insert.

The inner diameter of the insert at the rim is just the right size to catch the bullet a short distance above the theoretical intersection of bullet shank and ogive. So, if I can bore out the rest of ID of the insert, and prevent any other point of insert-to-bullet contact, i'll have my "prefect hollow cylinder" which will always engage that precise height above the base of the cartridge case. Hence, a consistent BTO. (If nothing else, like a non-flat or tiltable shell plate as discussed earlier, interferes!).

I realize that the "right" way to do this is to take the insert to a machinist and ask him to do it using a lathe or other machinery that only a machinist has on hand. But I am wondering if I could possibly do it myself. I do realize that perfect concentricity of the drill bit (or other suitable cutter device?) with the insert's centreline is critical, especially on the Redding die which encapsulates the cartridge case and bullet both before letting the bullet enter the insert. If the boring is off center at all, the pre-centered bullet will crash into one side of the insert instead of entering it smoothly. So, I doubt I can "do this at home".

I have the following applicable tools in my home workshop to use in this effort:

- A high quality 17" 1.5 hp floor standing drill press with infinitely variable drive speed and even digital rpm display

- A modest collection of drill bits in the "usual" sizes, but not any "unusual" sizes. It turns out that a drill bit with diameter of "about" 9/32" would be the right size to use. A 1/4" drill bit would be too small. A 5/16" drill bit would be too large (It would make the "hollow tube" wall too thin, and would require incredible accuracy in centering of the drill bit in the insert opening). Home Depot offers such a 9/32" drill bit, only via online ordering, and I had ordered one on Monday, and my wife just told me that it has arrived at our house. So, I have THAT part of the required solution, for either me or a machinist to use.

Is there ANY PRACTICAL way I can do this at home? (I'm thinking you'll say "no", but thought I'd ask)

And yes, it IS worth trying, as this approach is exactly how I successfully solved the exact same problem with my 6.5 Creedmoor Redding Compeition seating die. But I had a local gunsmith right nearby who could do it literally the next day for me on his lathe. I don't have such a resource in my new home city.

Jim G

 

[Jim Watson]

A reamer is more precise than a drill for taking out small amounts from an existing hole. Costs more, though.

that would have flipped the results in my favor if a single shot had been in the next advantageous position.

A couple of us worked on magazines and loads for .45 Minor IDPA ESP.
Midrange loads were simple, I am still shooting them for all purposes because my recoil tolerance has declined.
We had designs for 9 round 1911 magazines that fit The Box. That gave us 19 rounds to get a maximum of 18 hits with one reload.
I also have a .45 2011 to get the full 10, so 21 tries to get 18 hits, just like a 9mm.
We usually picked up a couple of points as the bigger bullets hit the perforation to a higher zone, Joe once gained six points.

 

[GeoDudeFlorida]

Ok, I want to "bore out" the seating insert on my 9mm Redding Competition die.

The objective is to prevent any contact of the inside of the seater insert with either the bullet meplat or ogive, except at just ONE point: The very bottom "rim" of the seater insert.

The inner diameter of the insert at the rim is just the right size to catch the bullet a short distance above the theoretical intersection of bullet shank and ogive. So, if I can bore out the rest of ID of the insert, and prevent any other point of insert-to-bullet contact, i'll have my "prefect hollow cylinder" which will always engage that precise height above the base of the cartridge case. Hence, a consistent BTO. (If nothing else, like a non-flat or tiltable shell plate as discussed earlier, interferes!).

I realize that the "right" way to do this is to take the insert to a machinist and ask him to do it using a lathe or other machinery that only a machinist has on hand. But I am wondering if I could possibly do it myself. I do realize that perfect concentricity of the drill bit (or other suitable cutter device?) with the insert's centreline is critical, especially on the Redding die which encapsulates the cartridge case and bullet both before letting the bullet enter the insert. If the boring is off center at all, the pre-centered bullet will crash into one side of the insert instead of entering it smoothly. So, I doubt I can "do this at home".

I have the following applicable tools in my home workshop to use in this effort:

- A high quality 17" 1.5 hp floor standing drill press with infinitely variable drive speed and even digital rpm display

- A modest collection of drill bits in the "usual" sizes, but not any "unusual" sizes. It turns out that a drill bit with diameter of "about" 9/32" would be the right size to use. A 1/4" drill bit would be too small. A 5/16" drill bit would be too large (It would make the "hollow tube" wall too thin, and would require incredible accuracy in centering of the drill bit in the insert opening). Home Depot offers such a 9/32" drill bit, only via online ordering, and I had ordered one on Monday, and my wife just told me that it has arrived at our house. So, I have THAT part of the required solution, for either me or a machinist to use.

Is there ANY PRACTICAL way I can do this at home? (I'm thinking you'll say "no", but thought I'd ask)

And yes, it IS worth trying, as this approach is exactly how I successfully solved the exact same problem with my 6.5 Creedmoor Redding Compeition seating die. But I had a local gunsmith right nearby who could do it literally the next day for me on his lathe. I don't have such a resource in my new home city.

Jim G

To be clear, I am going to ask how you are measuring your powder down to the thousandths of a grain and how sure you are of your check method. If +/- .001” is significant +/- .001gr is too. There are threads on this forum about measuring down to the thousands of grams, BTW so the subject is of consequence.

 

[JimGnitecki]

We usually picked up a couple of points as the bigger bullets (i.e. 45acp vs 9mm) hit the perforation to a higher zone, Joe once gained six points.

Some people might call this "gaming", but I see it as being fully within the spirit of IDPA / IPSC, as in real life (which the game is supposed to be a fictional version of), the "wider" bullet might just hit an artery or other critical target where the smaller bullet through the exact same point of entry would just barely miss.

However, I reject Dr. Falkner's theory that larger hole diameter makes a more effective stop than a smaller hole diameter. I believe that a massively larger energy dump clearly stops the bad guy's attack faster than a larger hole, and I think a .357 SIG and .357 Magnum both prove the point. When I worked at The Texas Department of Public Safety, the .357 SIG was praised by actual in-the-field officers, who described it as the perp being hit "by a bolt of lightning", and going down regardless of body adrenaline or drug level. Also, a .357 115g would go through a truck door and still deliver lethal force, whereas the .45 acp 230g would not.

So, if I were to get into that game again at some point, I'd be shooting a .357 SIG or a very hot 9mm load, and taking the recoil penalty, because that's within the true spirit of the game.

Just sayin'.

Jim G

 

[JimGnitecki]

To be clear, I am going to ask how you are measuring your powder down to the thousandths of a grain and how sure you are of your check method. If +/- .001” is significant +/- .001gr is too. There are threads on this forum about measuring down to the thousands of grams, BTW so the subject is of consequence.

I never claimed to be able to measure powder drop to "thousandths of a grain"! The standard Dillon powder reservoir system I use cannot attain that level of accuracy, and you also need a prohibitively costly and very sensitive scale to get anywhere beyond (true) 0.1 grain weighing accuracy to actually weigh such precise loads accurately.

I view the BTO problem as being both easier and cheaper to solve than getting beyond the weighing accuracy I currently have, especially since ladder testing found a couple of nodes where small variances in powder weight did not appear to affect point of impact.

But I'd be glad, and grateful, if someone here can describe how to improve powder weight precision at an affordable cost!

Jim G

 

[243winxb]

Ok, I want to "bore out" the seating insert on my 9mm Redding Competition die.

The RCBS die set comes with 2 seating stems. Not a perfect fit to the bullets, but close enough. My COL variation was less then factory rounds.

The expander is an M type. This helps with bullet alignment. Perfect for lead bullets. My G3C is not accurate enough to notice, or its my poor eye sight these days?

 

[GeoDudeFlorida]

https://www.thehighroad.org/index.p...mation-busting-digital-scale-accuracy.759750/
There are many threads on scale accuracy and some prove the most accurate scales are NOT the most expensive.

Expecting perfection to cheap, easy and effortless is not reasonable. You just lost me. Go read the Reloading Wisdom thread. Lots of good info there. Good luck and try not to be such a git next time.

 

[JimGnitecki]

The RCBS die set comes with 2 seating stems. Not a perfect fit to the bullets, but close enough. My COL variation was less then factory rounds.

The expander is an M type. This helps with bullet alignment. Perfect for lead bullets. My G3C is not accurate enough to notice, or its my poor eye sight these days?

View attachment 1105728

The RCBS seating stems' 2 internal shape choices look similar to the Dillon ones. One shape for round nose and one shape for flat nose. And, yes, the Dillon "round nose" one was a BIG improvment over the Redding Competition die insert shape, simply because the Hornady HAP 115g bullet i am using does get successfulu caught by that Dillon insert decently low on its ogive, without any higher portion of the ogive or meplat touching the ID of the insert.

I guess we can see that it pays to examine a sample of the insert used on any specific seating die, regardless of overall die quality, to see if its specific inner shape will work with the specific bullet shape we want to use. Or, we need to change the bullet we use, whichever is easier / less costly for us to do.

Jim G

 

[PWC]

The OPs whole argument breaks down when it meets a revolver. It is an interesting read tho. I'm 78, short on components, and believe after Nov. things will get better within 2 more years, but I'm not interested in bug hole accuracy with handguns. In fact, for the purpose for which Sam Colt first invented them, a 3" group is better'n all in the same hole.

I'm going to drink Pepsi and eat popcorn and watch this thread tho....

 

[GeoDudeFlorida]

The OPs whole argument breaks down when it meets a revolver. It is an interesting read tho. I'm 78, short on components, and believe after Nov. things will get better within 2 more years, but I'm not interested in bug hole accuracy with handguns. In fact, for the purpose for which Sam Colt first invented them, a 3" group is better'n all in the same hole.

I'm going to drink Pepsi and eat popcorn and watch this thread tho....

Hand me a Dr. Pepper and pass the popcorn, please. I'm going to sit back and watch how many ideas are rejected because they're hard, or expensive, require learning some new skill, or take a lot of effort.

 

[JimGnitecki]

The OPs whole argument breaks down when it meets a revolver. It is an interesting read tho. I'm 78, short on components, and believe after Nov. things will get better within 2 more years, but I'm not interested in bug hole accuracy with handguns. In fact, for the purpose for which Sam Colt first invented them, a 3" group is better'n all in the same hole.

I'm going to drink Pepsi and eat popcorn and watch this thread tho....

Yes, revolvers introduce that "unadjustable" and leaky gap that makes BTO control far less helpful for accuracy. But still relevant for safety.

And, it's nice to see that we now have at least one in the "audience", who can see the pleasure in observing the whole brainstorming process with its quirks and differing perspectives.

When I worked for a few years with US Postal on contract IT projects, we had a couple of lovers on night shift who found a quiet room in the building to do some romancing in every night. They did not realize that the room had a security camera, and that an entrepreneurial employee who knows how well sex sells was literally selling tickets and treats to other employees who enjoyed watching.

Jim G

 

[JimGnitecki]

Hey guys, I know I am the OP who started this whole discussion, but I need to sign off for a day or so, as I am out of town having a performance mod done to my car, and the shop just called for me to come in from my hotel. I'll be spending the rest of the day in either the shop, test driving, or driving back to my home city. I'll look forward to more postings to read when I get back on! I hope to be able to putn together a list at some point of things we can do to make better ammo for handguns, showing the ideas starting with easiest and least costly and going upward in effort and cost, so that each shooter can decide what seems doable for them individually based on their budget and their comfort level on work and complexity.

Jim G

 

[Jim Watson]

And, yes, the Dillon "round nose" one was a BIG improvment

The great annoyance of the Dillon seating die is that it is adjusted by turning the whole die body in and out on coarse sloppy threads. OK if you get it adjusted for one bullet, one OAL, and stay with it, but if you want to make up different loads, it is a pain in the neck.
I have the Hornady Microjust (cheaper than Redding) in 9mm and .45 for 1050, an old Lyman in the 550 head for .45 Small.

 

[JimGnitecki]

The great annoyance of the Dillon seating die is that it is adjusted by turning the whole die body in and out on coarse sloppy threads. OK if you get it adjusted for one bullet, one OAL, and stay with it, but if you want to make up different loads, it is a pain in the neck.
I have the Hornady Microjust (cheaper than Redding) in 9mm and .45 for 1050, an old Lyman in the 550 head for .45 Small.

I agree the Dillon insert is good mostly for someone who is not chnaging bullets often, because as you said, changing the setting is frustrating. What shape is the Hornady insert, compared to the Dillon and Redding inserts?

Jim G

 

[lordpaxman]

A little off topic here, but if you make a setup cartridge at the COL(s) you want, it’s very easy to get the Dillon seater positioned within a few thou. It might not be as easy as a micrometer but it’s fast. I switch between Blue RN and RMR FPs all the time. And that includes flipping the seater stem . Takes less time than changing heads.
I’m still interested in the CBTO discussion, but not sure where that falls in the overall debate of accuracy related to bullet consistency, propellant, neck tension, case length, concentricity, charge weight, and on and on.

 

[higgite]

A little off topic here, but if you make a setup cartridge at the COL(s) you want, it’s very easy to get the Dillon seater positioned within a few thou. It might not be as easy as a micrometer but it’s fast. I switch between Blue RN and RMR FPs all the time. And that includes flipping the seater stem . Takes less time than changing heads.
I’m still interested in the CBTO discussion, but not sure where that falls in the overall debate of accuracy related to bullet consistency, propellant, neck tension, case length, concentricity, charge weight, and on and on.

By "on and on", I'm sure you meant to include ambient temperature, barrel fouling, powder position at instant of firing, primer seating depth, primer-to-primer-pocket fit and flash hole diameter.

 

[JimGnitecki]

I’m still interested in the CBTO discussion, but not sure where that falls in the overall debate of accuracy related to bullet consistency, propellant, neck tension, case length, concentricity, charge weight, and on and on.

All the factors you have listed are of course important when loading ammunition, and the RELATIVE importance depends upon what the ammo is being used for, and where it is on the safety spectrum. BTO specifically becomes particularly important:
- When the load is a "hot" load for that caliber, and/or
- When the firearm, or firearms, used to fire the ammo have preferred "bullet jump" dimensions
- When the firearm, or firearms, used to fire the ammo have particularly short or long leades
- When the bullet design and production results in a shape of, or in a lack of consistency in, the meplat, that makes COAL an unreliable way of measuring and controlling (a) the point at which the bullet engages the rifling and/or (b) the size of the combustion chamber.

If you want to TRY to order the various factors in terms of PRIORITY, obviously the relative priority depends upon the specifics of the load, firearm, and usage. But at leats from a SAFETY perspective, most shooters might agree that consistency of powder, powder charge, and BTO would normally rank higher than some of the other factors, since variances in these 3 could damage or destroy the firearm and more importantly injure or kill the shooter and close bystanders.

I started this thread to discuss BTO specifically because I have identified BTO as the most prominent issue on my current 9mm handgun load for my most accurate handgun, and the most important PAST issue on my long range (300 to 600 yards for me) rifle. I solved that rifle BTO issue by having a gunsmith subtly modify the seating insert on the 6.5CM Redding Competition seating die which had been creating the issue. So I KNOW from personal experience that addressing BTO is fruitful.

At least one other discussion participant has noted that BTO is a current area of interest and concern for 9 Major competitive shooters.

Hence my statement that the importance of BTO specifically varies with your needs and circumstances. But for some shooters doing some types of shooting, it does become perhaps one of the most important areas of focus.

Jim G