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

[jmorris]

A couple of us worked on magazines and loads for .45 Minor IDPA ESP.

We did shoot minor 45 ACP in SSR before ESR was created. 2.8 gn of Clays and a 230 gave just under 590 fps (needed ~ 550 fps to make minor). You could see them in flight, going down range if you were behind the shooter. The joke was “the rule book doesn’t say it’s got to go all the way through the cardboard…”

 

[jmorris]

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.

I would suggest just making another, when I have modified dies in the past they were all too hard to machine, until I annealed them. If you hit it with a file and it slides across vs making a cut, it’s going to be hard at least until you make it look like this and air cool.



But then you can machine them into what you want.



I fine it easier to just use spare Lee powder dies I have and machine the drop in insert for it.

 

[.38 Special]

This has been touched on, but it does seem to me that while this whole conversation is interesting from a technical sense, it is putting the cart before the horse. Has it been established - anywhere, by anyone - that a .010" tolerance is responsible either for significant accuracy loss or significant danger to the shooter?

I'd be fairly surprised if reducing that tolerance by a few thousandths would show up on a handgun target, and I certainly don't want anything to do with a load so close to the edge that .010" is enough to blow me up.

 

[jmorris]

I'd be fairly surprised if reducing that tolerance by…

That was the point at the top of #33, if you load 500 rounds, chance alone will give you a sample size that is perfect for you to test, directly against less than ideal rounds. Then there is no reason to guess, hope, wish, etc.

If you can’t tell any difference, I probably wouldn’t waste time chasing perfection in the area. If it helps you, even if it’s only mental, it would be worth it to continue.

From my testing what bullet you are seating makes A LOT more difference than how it’s seated as far as slight variation of seating depth goes. I don’t care how you seat, say a tumble plated bullet, it’s not going to shoot as well as a quality JHP, for example.

 

[lordpaxman]

@jmorris, I’m not sure I agree that just selecting a large 100-200 round sample based on COL or CBTO and seeing how that performs relative to the others from that batch would lead you to conclude whether or not the length was the factor in how well they grouped. They only way I see you could conclude that is if every other metric was constant. Perhaps that was implied but I think you’d need virgin brass, all the same length, bullets that were very consistent, charges all very consistent, measuring neck tension, not sure what else but length would have to be the only variable. And I’m talking pistol rounds intended for 20-50 yards. The PR crowd knows the factors that are important to control.

 

[Jim Watson]

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

The Hornady insert has a deep straight hole to clear the nose of the bullet; its mouth is beveled to not dig into the ogive.

The Lyman in my 550 has a solid hemispherical cavity, rather shallow. I THINK it bears on the nose or meplat rather than the edge on the ogive but I am not breaking my setup to look.

I have a little experiment for this afternoon or tomorrow, I will post results.

We did shoot minor 45 ACP in SSR before ESR was created.

I did, too.
I have some f 155 ammo on hand in case I want to go back to .45 but the occasional recent outing with a revolver has been in .38.
I LAMR with wadcutters (f 107, minimum 105 now) and reload with roundnose in Comp IIIs.

 

[jmorris]

They only way I see you could conclude that is if every other metric was constant. Perhaps that was implied but I think you’d need virgin brass, all the same length, bullets that were very consistent, charges all very consistent, measuring neck tension, not sure what else but length would have to be the only variable.

Well, if all of your other variables are all over the place, why would you care about one that, more than likely, is pretty far down on the list of significance?

Not to mention, unless you are looking to change everything you do, you would only alter the one and leave the rest of your routine “as is”. Now all you have to do is see if the one variable, seating depth variation, makes a difference on paper. Doesn’t matter much if other variables, cancel out or negate any added gain or not, if you are just trying to understand if elimination of slight seating depth variation makes your process better, worse or makes no difference at all, on target.

Then you can either check that box as “important” or scratch it off your list as a path that needs to be followed.

I suppose you could jump through all the hoops and change everything at once but then you won’t know what variables are key and what ones you didn’t have to mess with in the first place.

 

[JimGnitecki]

I would suggest just making another, when I have modified dies in the past they were all too hard to machine, until I annealed them. If you hit it with a file and it slides across vs making a cut, it’s going to be hard at least until you make it look like this and air cool.

View attachment 1105901

But then you can machine them into what you want.

View attachment 1105900

I fine it easier to just use spare Lee powder dies I have and machine the drop in insert for it.

View attachment 1105899 View attachment 1105898

Great suggestions in here! Thank-you!

Jim G

 

[JimGnitecki]

. . . I don’t care how you seat, say a tumble plated bullet, it’s not going to shoot as well as a quality JHP, for example.

Excellent point that has not been focused on in this thread so far! I have no experience with plated versus jacketed bullets, so this is very interesting to me.

 

[JimGnitecki]

The Hornady insert has a deep straight hole to clear the nose of the bullet; its mouth is beveled to not dig into the ogive.

The Lyman in my 550 has a solid hemispherical cavity, rather shallow. I THINK it bears on the nose or meplat rather than the edge on the ogive but I am not breaking my setup to look.

I have a little experiment for this afternoon or tomorrow, I will post results. . . .

Ah, the Hornady insert sounds good to me. No possiiblity of interference with the meplat.

The slight bevel at the mouth will protect against digging into the bullet AND will also improve consistency by lessening the risk of an incorrect MEASUREMENT of the BTO which could occur if you apply varying pressure on the press lever for different rounds during a session and so dig just a bit into the bullet ogive. A "knife edge" on the mouth would make such accidental human-caused variances much more likely.

Jim G

 

[JimGnitecki]

Well, if all of your other variables are all over the place, why would you care about one that, more than likely, is pretty far down on the list of significance?

Not to mention, unless you are looking to change everything you do, you would only alter the one and leave the rest of your routine “as is”. Now all you have to do is see if the one variable, seating depth variation, makes a difference on paper. Doesn’t matter much if other variables, cancel out or negate any added gain or not, if you are just trying to understand if elimination of slight seating depth variation makes your process better, worse or makes no difference at all, on target.

Then you can either check that box as “important” or scratch it off your list as a path that needs to be followed.

I suppose you could jump through all the hoops and change everything at once but then you won’t know what variables are key and what ones you didn’t have to mess with in the first place.

True! In fact, you would want to first do other things (like ladder testing), because their effect might be larger than the BTO variance reduction effect, so NOT doing the "larger impact" ones FIRST, you might unkowningly erroneously "prove" that BTO control is not worth doing because bypassing the ladder testing causes so much vertical stringing (because you are not at a node) that THAT effect totally hides the effect of BTO variance reduction!

So perhaps one of the conlusions we might reach in this thread is that the ORDER in which you test and evaluate individual "potential improvements" is rather important. First do the ones that in general are known to have the largest positive impacts, and then work your way down towards the improvements that are known to have smaller, but still additively helpful, impacts.

Jim G

 

[higgite]

Ah, the Hornady insert sounds good to me. No possiiblity of interference with the meplat.

The slight bevel at the mouth will protect against digging into the bullet AND will also improve consistency by lessening the risk of an incorrect MEASUREMENT of the BTO which could occur if you apply varying pressure on the press lever for different rounds during a session and so dig just a bit into the bullet ogive. A "knife edge" on the mouth would make such accidental human-caused variances much more likely.

Jim G

That concern can be eliminated for any seating stem by measuring CBTO with a comparator having a larger ID where it contacts the ogive than the stem’s ID where it contacts the ogive. I have Hornady, RCBS and Lee seating dies for 9mm and 45 ACP. None of the stems contact the ogive close to its junction with the bearing surface. I’m not endorsing a “knife edged” seating stem, just pointing out that it’s a low hurdle to jump over for CBTO measurements.

 

[JimGnitecki]

That concern can be eliminated for any seating stem by measuring CBTO with a comparator having a larger ID where it contacts the ogive than the stem’s ID where it contacts the ogive. I have Hornady, RCBS and Lee seating dies for 9mm and 45 ACP. None of the stems contact the ogive close to its junction with the bearing surface. I’m not endorsing a “knife edged” seating stem, just pointing out that it’s a low hurdle to jump over for CBTO measurements.

I can see why you answered my concern the way you did. I was not clear enough. I was not worried about getting a wrong measurement because the measuring gage would potentially be applied at the "crushed zone" where the die insert contacted. Instead, I was actually worried about the occasional bullet having the insert dig into it AND AS A RESULT NOT ACTUALLY PUSH THE BULLET TO THE SAME FINAL BTO, because a portion of the "apparent travel" of the insert was instead actually consumed in crushing into the bullet a bit. That situation would be detected if 100% of the cartridges being loaded are measured for actual BTO, but would NOT necessarily be detected if only a sampling of the completed cartridges are measured. THAT is what I was concerned about.

Jim G

 

[higgite]

You don't have to SHOUT. I can read lower case.

 

[BJung]

To me, handgun seating dies will press a load with a constant COL. If I wanted a consistent COAL, I would measure the COAL of the bullet to base before loading and separate the bullets accordingly. Maybe a short metal or plastic tube or sleeve at the hardware store that has an Inside Diameter that will touch the ogive. Using an Outside Caliper, one can measure and look for a consistent length from the base of the bullet to the end of the sleeve.

 

[JimGnitecki]

To me, handgun seating dies will press a load with a constant COL. If I wanted a consistent COAL, I would measure the COAL of the bullet to base before loading and separate the bullets accordingly. Maybe a short metal or plastic tube or sleeve at the hardware store that has an Inside Diameter that will touch the ogive. Using an Outside Caliper, one can measure and look for a consistent length from the base of the bullet to the end of the sleeve.

Your idea would ensure that all the bullets you select would be the same length. That's a good thing, and your methodology is inexpensive and effective. BUT the problem many of us are encountering is that the seating dies we have will take all those "perfect length" bullets and still seat them differently. That's why we are looking for an easy way to get seating dies modified so that they consistently seat the bullets to the exact same point on the ogive.

Jim G

 

[jmorris]

True! In fact, you would want to first do other things (like ladder testing), because their effect might be larger than the BTO variance reduction effect, so NOT doing the "larger impact" ones FIRST, you might unkowningly erroneously "prove" that BTO control is not worth doing because bypassing the ladder testing causes so much vertical stringing (because you are not at a node) that THAT effect totally hides the effect of BTO variance reduction!

Ladder testing at “normal” handgun ranges makes me think more about the handgun than the load. That’s generally a longer range concept, at least in order to see the variations or not. I can load a mag with different loads completely at 7 yards and I’m not going to see a huge change in group size because the distance from firearm to target doesn’t allow the same dispersion as I would see if it were 300 yards away.

“Handgun” covers a lot of ground. The way many are as well as the way people aim them, targets, distance, “acceptable group size”, etc, few gains will likely be seen as the tools themselves don’t have the ability to repeat sufficiently. Others one should treat as a rifle, in process, as they can attain the same degree of accuracy.



There is no amount of perfecting BTO that will make the handgun on the right come close to shooting as well as the one on the left even with BTO variation; however, the one on the left had the best chance of showing me on target because it’s capable of repeating shot placement to a degree where any change has a possibility of showing up.

So the particular handgun, is going to make a huge difference. To the point of even changing the direction of conversation.

Excellent point that has not been focused on in this thread so far! I have no experience with plated versus jacketed bullets, so this is very interesting to me.

After the handgun, if we can remove the human error, the bullet is the most important item as far as accuracy is concerned. You might play with a few different styles, cast, swaged, jacketed (open base FMJ’s and solid base JHP’s) as well as plated. They all have something going for them but it’s not always accuracy. Certainly worth knowing what they are capable of and how different they can be vs one another.

 

[JohnKSa]

1. On a high power load where combustion pressure is high enough to be approaching the published safe limit for the caliber you are loading for. For example, 9 Major or 357 Magnum hot loads. NOT measuring BTO here can cause catastrophic firearm damage, and shooter and nearby spectator injury or death.

BUT the problem many of us are encountering is that the seating dies we have will take all those "perfect length" bullets and still seat them differently.

In terms of your #1 concern, that's not an issue. The problem you describe (bullet deformation) will result in the bullet being seated less deep than expected, which would result in lower pressure--not more pressure.

I'm interested in the idea that the same seating die, pushing nominally identical bullets into uniform cases reshaped by the same dies is giving inconsistent results.

If the cases and bullets are all the same, then the seating pressure should also be the same for each bullet/case combo. If some are getting deformed in the process while others aren't, that indicates the seating pressure is higher for some than others, the bullet hardness is varying or the cases are not the same shape. Seems like eliminating or controlling those variables (which also might be expected to affect accuracy) would be a better place to start working on the problem.

 

[CQB45ACP]

Only eight of ten shots on target from 30 yards! Failed to check the BTO I’ll bet.

https://fox59.com/greenwood-park-ma...-greenwood-park-mall-shooting-within-seconds/

 

[jmorris]

I'm interested in the idea that the same seating die, pushing nominally identical bullets into uniform cases reshaped by the same dies is giving inconsistent results.

Well, they are only nominally inconsistent.

 

[JimGnitecki]

In terms of your #1 concern, that's not an issue. The problem you describe (bullet deformation) will result in the bullet being seated less deep than expected, which would result in lower pressure--not more pressure.

I'm interested in the idea that the same seating die, pushing nominally identical bullets into uniform cases reshaped by the same dies is giving inconsistent results.

If the cases and bullets are all the same, then the seating pressure should also be the same for each bullet/case combo. If some are getting deformed in the process while others aren't, that indicates the seating pressure is higher for some than others, the bullet hardness is varying or the cases are not the same shape. Seems like eliminating or controlling those variables (which also might be expected to affect accuracy) would be a better place to start working on the problem.

If the bullet is seated LESS deep, it's still an issue, because then the bullet jump to the rifling is shortened, and might even get the bullet jammming into the rifling if the originally intended jump was short to begin with. My lever action rifle for example prefers shot jump, but not sure how it would react to the bullet being jammed right into the rifling.

And if you have first addressed all other variables, and still are getting very inconsistent seating, it iS the die insert shape that is the problem, and it's uusally because the insert is making contact at the meplat versus the ogive, and the meplat on an hollowpoint jacketed bullet, as mentioned earlier, is too inconsistent to use as a seating control.

Jim G

 

[JimGnitecki]

Only eight of ten shots on target from 30 yards! Failed to check the BTO I’ll bet.

https://fox59.com/greenwood-park-ma...-greenwood-park-mall-shooting-within-seconds/

8 of 10 shots on target with a handgun in a true gunfight against a rifle armed assailant at 30 yards is sensationally good. In most actual gunfights the participants are so agitated that they are unlikely to hit with most of their shots. In fact in at least one documented police officer versus bad guy gunfight at a gas station many years ago, both participants emptied their magazines without a single hit. No kidding.

Jim G

 

[higgite]

8 of 10 shots on target with a handgun in a true gunfight against a rifle armed assailant at 30 yards is sensationally good. In most actual gunfights the participants are so agitated that they are unlikely to hit with most of their shots. In fact in at least one documented police officer versus bad guy gunfight at a gas station many years ago, both participants emptied their magazines without a single hit. No kidding.

Jim G

When asked why he shot the bad guy 8 times, the good samaritan said, "Because I ran out of ammo."

 

[CQB45ACP]

8 of 10 shots on target with a handgun in a true gunfight against a rifle armed assailant at 30 yards is sensationally good. In most actual gunfights the participants are so agitated that they are unlikely to hit with most of their shots. In fact in at least one documented police officer versus bad guy gunfight at a gas station many years ago, both participants emptied their magazines without a single hit. No kidding.

Jim G

Probably same when surprised by a charging grizzly.

In the real world, fine tuning COL or BTO makes little difference.

 

[RashQuestion]

8 of 10 shots on target with a handgun in a true gunfight against a rifle armed assailant at 30 yards is sensationally good. In most actual gunfights the participants are so agitated that they are unlikely to hit with most of their shots. In fact in at least one documented police officer versus bad guy gunfight at a gas station many years ago, both participants emptied their magazines without a single hit. No kidding.

Amazing what happens when your adrenaline kicks in!!! Or when someone is shooting back at you!!!

Probably same when surprised by a charging grizzly.

Or as described above!!!

Thank God I haven't been faced with the any of the above!