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

[PWC]

I'm outta' Pepsi and popcorn now....

 

[Jim Watson]

I hope better than apples to oranges, maybe tangerines to oranges.
I am loading .45 ACP on a Super 1050 with Hornady seater and MicroJust spindle; and .45 Small on a 550B with Lyman seater.
The loads are the same, mixed brass, Federal primers, Bullseye powder, IbejiHeads coated 200 gr roundnose bullet.
Target OAL 1.250"
Ten round grab samples measured on dial caliper to the half thou.

1050 + Hornady seater
1.248 - 1.2515" in mixed commercial brass.
1.243 - 1.254" in TZZ Match 86 brass, which I had considered my best stuff. Nope.

550 + Lyman seater
1.249 - 1.252" in Blazer brass
1.249 - 1.251" in Federal brass.

Lyman plug bearing on nose is at least as good as Hornady ogive plug for my loads.

 

[JimGnitecki]

That's pretty good, Jim. It's better than the .004" variance I am getting with my Dillon die on the XL750 with the toolhead bolted in. I'm going to try to measure up the shell plate on the XL750 I am currently setting up for .357 Mag, and see how its flatness or lack thereof compares to what was posted earlier in the thread.

Jim G

 

[JohnKSa]

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.

I notice the example you give is in a rifle--which makes sense. The OP specified that this thread is about handgun loads. I think it's going to be very hard to seat a bullet so close to the lands in a handgun that the bullet deformation from a seating die results in it being jammed into the lands badly enough to raise the pressure to a dangerous level. Maybe if you are single loading rounds in a semi-auto which is kind of a pathological example. Obviously it can't happen in a revolver and would be difficult in a semi-auto since over-length rounds tend to not fit in the magazine.

The idea that inconsistent bullet deformation from a seating die is going to cause a dangerous situation in a handgun seems pretty far-fetched.

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...

If all those variables have really been addressed, what is causing the die to deform one bullet, but not another identical bullet? The same die applying the same force to the same place on a number of identical bullets will deform them all the same amount.

 

[JimGnitecki]

. . . The same die applying the same force to the same place on a number of identical bullets will deform them all the same amount.

No! That's the point. More than one die I have tried in the past has NOT applied the same force to the same place, because the bullets were not securely held in the insert, because the insert grabs the bullets at the meplat instead of the ogive.

 

[JohnKSa]

So it's a matter of making sure the bullet is lined up before the die applies force?

 

[JimGnitecki]

So it's a matter of making sure the bullet is lined up before the die applies force?

Actually, yes, that;s ONE requirement for your press and die setup. But the requirement that precedes that is making sure that the die is a "good fit" for the bullet you intend to use. In both my recent 9mm handgun and my recent 6.5 Creedmoor reloading, the Redding die seating inserts had the wrong internal shape. In both cases, when I pulled the insert out of the die, and pushed a bullet gently into it (outside the die) until it "bottomed", I could physically "rock" the bullet at the mouth of the insert. That proved that the iD of the die insert somewhere above the mouth was too small, and was bumping up against the meplat instead of the ogive.

If the bullet can rock when "seated" in the insert, the ID of the insert is wrong for that bullet. A gunsmith "bored out" the 6.5 CM insert for me, and that totally solved the problem of BTO variance. Which is why I said earlier in this thread that I need to do the same thing with the 9mm die insert I think.

Jim G

 

[JohnKSa]

I could physically "rock" the bullet at the mouth of the insert.

If the bullet is lined up correctly, the bottom of the bullet is even and the mouth of the case isn't irregular, then that should prevent the bullet from rocking in practice--when it's actually being used to seat a bullet into the case. I'm not saying that the rocking is ideal; I just don't see how it could be a problem if everything else is taken care of properly.

...6.5 CM insert...

Another rifle example.

 

[JimGnitecki]

If the bullet is lined up correctly, the bottom of the bullet is even and the mouth of the case isn't irregular, then that should prevent the bullet from rocking in practice--when it's actually being used to seat a bullet into the case. I'm not saying that the rocking is ideal; I just don't see how it could be a problem if everything else is taken care of properly.Another rifle example.

The rocking per se is not the problem. It is the PROOF that the die insert has captured the meplat instead of the ogive. That's a problem with holowpoint jacketed bullet because the meplat is NOT consistent, and should therefor NOT be used to set the BTO.

If you think about it and draw it out on a piece of paper, you'll see that.

Jim G

 

[JohnKSa]

So only an issue with JHP bullets that have inconsistent meplats--i.e. not identical bullets.

 

[JimGnitecki]

So only an issue with JHP bullets that have inconsistent meplats--i.e. not identical bullets.

I don't know if this applies ONLY to JHP bullets. JHP bullets are defintiely known to have variances in meplats. But that is the only type of bullets that I have used in the last few years. Now, I am going to need to also rreload 38 Special and 357 Magnum lead bullets because lead bullets are required in Cowboy Action Shooting, for safety reasons (metal targets sometimes at very close ranges). So, I need to learn how variable LEAD buellets can be also, and whether or not meplats can be consistent enough to use instead of ogives. Others on this thread can probably give us a summary of what types of bullets can be reliably measured for BTO via the meplat instead, and which ones cannot?

There are so many types of bullets, for example:
Lead cast
Plated cast
Jacketed with unjacketed base
Hollowpoint jacketed
etc

Maybe someone on this thread who has loaded many types of bullets can summarize for us which types vary more than others, and WHERE on the bullet they vary?

Jim G

 

[JohnKSa]

Without getting into whether or not the real problem is the die or whether it's a problem with poor quality control of bullets, or maybe some other factor, what kind of accuracy degradation is this intended to correct?

I did an experiment shooting different kinds of 9mm "budget/practice" ammo through one pistol onto one target awhile back. The test consisted of 10 rounds, 6 different kinds of ammo, 5 different brands represented, shot at 15 yards. Now, I didn't check the BTO on all that ammo, but considering all 6 of the loads used different bullets, loaded into different cases, likely using different powders, assembled by at least 5 different manufacturers, I'm willing to bet that there was a good bit of variation in just about every aspect of the cartridges one would care to measure. And yet all the bullets ended up hitting the 15yd target in a single 2" group.

That makes me skeptical that small variations in COAL in a single loading (same bullet/powder/case prep/primer/etc.) are going to cause any sort of practical degradation in handgun accuracy.

 

[JimGnitecki]

Without getting into whether or not the real problem is the die or whether it's a problem with poor quality control of bullets, or maybe some other factor, what kind of accuracy degradation is this intended to correct?

I did an experiment shooting different kinds of 9mm "budget/practice" ammo through one pistol onto one target awhile back. The test consisted of 10 rounds, 6 different kinds of ammo, 5 different brands represented, shot at 15 yards. Now, I didn't check the BTO on all that ammo, but considering all 6 of the loads used different bullets, loaded into different cases, likely using different powders, assembled by at least 5 different manufacturers, I'm willing to bet that there was a good bit of variation in just about every aspect of the cartridges one would care to measure. And yet all the bullets ended up hitting the 15yd target in a single 2" group.

That makes me skeptical that small variations in COAL in a single loading (same bullet/powder/case prep/primer/etc.) are going to cause any sort of practical degradation in handgun accuracy.

I suppose it depends on your individual definition of "accuracy". To me, a 2" group at 15 yards would be awful. My SIG P210A shoots 3/4" groups at 25 yards. And with the Craig Fantoms and Omens that I used to own (sub-compact "chopped and channeled officers models" built on Caspian frames by Fred Craig), when I was younger, shooting .38 Super, 9mm, 40 S&W, and 45 acp, I routinely shot 3" and sometimes 2" groups at 50 yards, with self defence, not powderpuff loads, despite those pistols' diminuative size. When a handgun can deliver that kind of performance, you naturally want to push the limits further.

Jim G

 

[James Petti]

Just to jump back in this before it's too late(for me), here is something of interest to me and perhaps to others.

Bullet seater guides. The RCBS Green Machine uses(used) such a strategy and has perhaps one of the worst reputations for seat consistency. Pictures of the things are impressive but their performance is not.

Seat die brands. Shown are RCBS and Dillon .357 seat dies with a bullet dropped in and turned on their sides. The RCBS is centered, due to a machined step which I could not photograph. The Dillon has no such feature and is tilted in the die.

I have no way of measuring runout and don't know if it's feasible on such a short case/bullet. When loaded, they both look/shoot the same to me. The advantage of the Dillon seat die is it's easy to clean, but since I no longer shoot grease lubed bullets...

 

[jmorris]

I'm outta' Pepsi and popcorn now....

I had you down as a Dr. Pepper guy…

Obviously it can't happen in a revolver and would be difficult in a semi-auto since over-length rounds tend to not fit in the magazine.

CZ’s are known to have short leads. Back around ‘02 David (Precision Bullets) switched from cast 230’s to swaged and they had a small flat spot on the tip. All of the folks that used normal 230 RN OAL had sticking bullets, shorten the OAL by .030” and they run like a top.

when I pulled the insert out of the die, and pushed a bullet gently into it (outside the die) until it "bottomed", I could physically "rock" the bullet at the mouth of the insert.

There are DIY methods for altering a seating stem for a particular bullet, there are also businesses that will make a custom one for the bullet you send them.

https://www.whiddengunworks.com/product/custom-seater-stems/

 

[fxvr5]

In reading this thread, several thoughts come to mind.

1. The first thing to do is show that the small differences in OAL or BTO actually result in accuracy degradation in a handgun. If the gun or ammo can’t tell the difference, you’re wasting your time.

2. How to test it? Since you want to remove any and all influence from the shooter, at the least you would require a Ransom Rest. Even better, a barrel fixture device would be best. For this, you remove the barrel and place it in the device. This removes any tolerances issue produced by the gun (the barrel in the gun). Only then are you truly testing just the ammo (in that barrel).

3. How much of a difference in group size is enough to show a benefit in reducing tolerances? You can get a 3:1 difference in group size with the same ammo. (See the link below.)

4. How many shots for your test? Articles on the web show you get differences in group size even using the same ammo - with the gun fired in a Ransom Rest. This includes shooting 50-shot groups.

https://www.ssusa.org/articles/2021/2/17/accuracy-testing-how-many-shots-in-the-group

Based on this I think a lot of testing would be required to demonstrate that small differences in tolerances actually make a difference. And if it’s not tested properly or with enough ammo and in a proper test paradigm, you haven’t proven a thing.

 

[higgite]

I suppose it depends on your individual definition of "accuracy". To me, a 2" group at 15 yards would be awful.
Jim G

Excuse me while I put my boots on.

When a handgun can deliver that kind of performance, you naturally want to push the limits further.

Jim G

I would disagree with "naturally", but that's just me. I have a couple of pistols that will do that, but I have no desire to chase a .001" inch improvement in the CBTO of my ammo.

 

[CQB45ACP]

In reading this thread, several thoughts come to mind.

1. The first thing to do is show that the small differences in OAL or BTO actually result in accuracy degradation in a handgun. If the gun or ammo can’t tell the difference, you’re wasting your time.

2. How to test it? Since you want to remove any and all influence from the shooter, at the least you would require a Ransom Rest. Even better, a barrel fixture device would be best. For this, you remove the barrel and place it in the device. This removes any tolerances issue produced by the gun (the barrel in the gun). Only then are you truly testing just the ammo (in that barrel).

3. How much of a difference in group size is enough to show a benefit in reducing tolerances? You can get a 3:1 difference in group size with the same ammo. (See the link below.)

4. How many shots for your test? Articles on the web show you get differences in group size even using the same ammo - with the gun fired in a Ransom Rest. This includes shooting 50-shot groups.

https://www.ssusa.org/articles/2021/2/17/accuracy-testing-how-many-shots-in-the-group

Based on this I think a lot of testing would be required to demonstrate that small differences in tolerances actually make a difference. And if it’s not tested properly or with enough ammo and in a proper test paradigm, you haven’t proven a thing.

So are you suggesting less talking and more (heck any) testing?

 

[fxvr5]

So are you suggesting less talking and more (heck any) testing?

Right. The whole crux in this thread is that tightening handgun ammo tolerances by a couple thousandths will improve accuracy. But it has not been demonstrated.

 

[jmorris]

Articles on the web show you get differences in group size even using the same ammo - with the gun fired in a Ransom Rest.

They still require human involvement in both mounting and use. You can learn a lot with them but one of the things you learn is that they are not perfect either.

I played with one for awhile, they are a fairly quick way to test A,B,C. For example I quickly found what this pistol preferred.



Not going for point of aim as much as group size.



It can be improved upon though, this is the one I made after using the Ransom, similar with just slight changes, you can see the difference on paper pretty easy, with the same load/firearm.



Even better is to use an optics equipped pistol to ensure exact return, I even went so far as to make my own inserts to hold the firearms.

1. The first thing to do is show that the small differences in OAL or BTO actually result in accuracy degradation in a handgun. If the gun or ammo can’t tell the difference, you’re wasting your time.

Absolutely.

 

[James Petti]

I don't understand what practical use is there of reducing/eliminating the variables of the shooter. Handgun vs machinerestgun.

So, you've broken into my house, have you? Just wait till I fetch my Ransom rest, then you'll be sorry!

 

[higgite]

They still require human involvement in both mounting and use. You can learn a lot with them but one of the things you learn is that they are not perfect either.

I played with one for awhile, they are a fairly quick way to test A,B,C. For example I quickly found what this pistol preferred.

View attachment 1106280

Not going for point of aim as much as group size.

View attachment 1106282

It can be improved upon though, this is the one I made after using the Ransom, similar with just slight changes, you can see the difference on paper pretty easy, with the same load/firearm.

View attachment 1106283

Even better is to use an optics equipped pistol to ensure exact return, I even went so far as to make my own inserts to hold the firearms.

View attachment 1106284



Absolutely.

Were both targets shot with the optics equipped pistol?

 

[jmorris]

No, those were with the 1911.

I didn’t make my own grip inserts until after I could see my machine provided better results, then switched over.

If I were trying to figure out where the Ransom introduced error, I probably would have looked into it closer but that wasn’t my goal.

 

[243winxb]

All my RCBS seater plugs contact the flat nose of my 9mm, 38, 357, 44 mag cast bullets. Some were modified to do so. My die sets are from the 70s, except for the 2021 9mm Luger set.

Contact RCBS to see if custom plugs are available.

 

[JohnKSa]

All of the folks that used normal 230 RN OAL had sticking bullets, shorten the OAL by .030” and they run like a top.

I'm assuming there were lots of gun blowups and injuries due to this dangerous issue... Right?

I suppose it depends on your individual definition of "accuracy". To me, a 2" group at 15 yards would be awful. My SIG P210A shoots 3/4" groups at 25 yards.

OK! Now we have some kind of frame of reference for the kind of "problem" you're trying to correct and the kinds of guns you are talking about shooting. Yes, I suppose that if you're trying to nail down loads that will shoot under 4MOA with a pistol, some of what you are saying might make sense.

Not the part about BTO being potentially dangerous, of course, and then there's the fact that pistols that shoot that well are not very common which is why my comment included the word "practical".

1. The first thing to do is show that the small differences in OAL or BTO actually result in accuracy degradation in a handgun.

Radical concept...