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GENERAL => Ammunition, questions, and handloading techniques => Topic started by: kerncat on October 12, 2010, 01:13:47 PM

Title: How to determine Max OAL for a CZ Pistol
Post by: kerncat on October 12, 2010, 01:13:47 PM
I'm planning to load 200 grain XTP Hornady bullets for my .45 CZ 97.  I want to stick with my HP38 powder that I use in other calibers.  I'm looking for a mid range load and find other JHP 200 grain loads using HP38 at about 5.3 grains on the lower end and up to 5.9 grains at the upper limit.  I've looked for specifics on the XTP as I've not loaded them before and just don't seem to find any specific data in all the charts I've looked at.  Anyone offer any suggestions before I just begin low and work up?  I'd like an accurate load at about 850 fps or so thanks.

Moderator Note
Hodgdon HP-38 powder and Winchester 231 powder are the exact same products sold under 2 different names. So when you see load data for one, you can freely substitute the other.
Title: Re: 200 grain Hornady XTP loads for my CZ97
Post by: Wobbly on October 13, 2010, 10:51:23 PM
Mr Cat -
I load 45ACP, but not for the CZ. However maybe I can get you started. I found this data online at the Hodgdon load center...

200gr SPR JHP   Win 231   0.451"   1.155"     5.2gr    794fps    12,700 CUP    5.9gr    906fps    16,700 CUP

Some thoughts...

? The Speer and the Hornady are both 200gr jacketed, so we can safely start with that load
? The HP38/W231 is a great powder for this round and you'll enjoy shooting it.
? The XTP can be slightly more trouble to load. The XTP brings the full .451 diameter forward of the case mouth and a lot of CZs don't like that. So the first thing to do is load a test round (no powder; no primer) at the 1.155" and make sure your chamber can live with that OAL. Drop that into your disassembled "naked" barrel and see if you can freely twist the cartridge around in the chamber. If not, then we have work to do.
? If the 1.155" test cartridge will drop in all the way, then load five rounds at 5.2gr, five at 5.4gr, five at 5.6gr, and five at 5.8gr... just as you would always "work up" a new load.

Let us know how it goes. All the best.  ;)
Title: Re: 200 grain Hornady XTP loads for my CZ97
Post by: kerncat on October 15, 2010, 05:38:13 PM
Many thanks for the info.  I'd heard that about the XTP and had figured to pull the barrel and use it as a gauge for the reloads.  I don't like to shorten things up much because of pressure situations with the bullet sitting further into the case, but I'd guess there is some room to maneuver and certainly I can walk the recipe back a little if concerned.  Really appreciate the info and I'll keep you posted. 

"Edit Post"...I got info from Hornady about the load, and man does it ever vary from what the Hodgdon spec is for the Speer bullet. The guy at Hornady said to start at 5.7 grains for 800 fps and the top end is 6.8gr for 950 fps. He indicated a COL at 1.230". I got a feeling that the 1.230" would pose a problem if the 1.155 could be "iffy". Also the loads are significantly higher on both the top end and the lower end.  I have the Lyman book and although it doesn't have the XTP listed it does have a 225 grain JHP shown and the loads are down where the Hodgdon loads seem to be. I'm going to do a little checking because from what I'm seeing the info I got from Hornady might be a bit on the hot side. They should know but mistakes can happen.  Thanks again.
Title: Re: 200 grain Hornady XTP loads for my CZ97
Post by: Wobbly on October 15, 2010, 07:51:11 PM
Mr Cat -
Well, books and help line people can certainly be valuable, but there's no substitute for knowing exactly how your bullet interacts with your barrel. As I said, the XTP is special and your CZ chamber is also special. So let's not guess, let's find out EXACTLY. Sound good?

There are several ways to do this, but here's my method.... Fit a new Jacketed or Plated bullet into a fired case. (No powder; fired primer.) If you try 2 or 3 bullet/case combinations you'll end up with 1 or 2 where the bullet is a snug "push fit". Fit the bullet inside the case, but leave the OAL out at an exaggerated length; any OAL longer than what you need. Working with your barrel REMOVED from the gun, slide this "test cartridge" into the chamber. At some point it will stop going into the chamber. In other words, whatever the bullet is striking is keeping the test cartridge from going in all the way. At this point, if you continue to push, the bullet will slide back into the case until the mouth of the case comes to rest on the end of the chamber (or "head spaces"). So a) whatever the bullet was striking has pushed the bullet back into the case, and b) the case has fully entered the chamber. Follow?



Now, slowly and carefully withdraw the test cartridge and measure its new length. Do this with other bullets from the same batch and other cases until you start to see the same number again and again. That measurement is your exact chamber length for that bullet in that barrel. For many reasons we need an additional setback distance, so subtract at least 0.015" from that number to obtain your Maximum Usable OAL.



So let's assume your test cartridge keeps giving you a number like 1.177". We subtract our setback and get 1.177" - 0.015" to equal 1.160". You see I've backed off an additional .002" because 1) it's simply easier to read on a caliper, 2) the chances of finding a load for 1.162" is impossible, whereas 1.160 is probably pretty good, and 3) we're talking less than a human hair, so gee whiz give it a break!  ;D  ;D 

NOTE: So 1.160" becomes the maximum permissible OAL, or more simply Max OAL. The load data from Hodgdon used an OAL of 1.155" and without experience you really don't want to load shorter than published data. Therefore, 1.155" becomes the minimum permissible OAL, or Min OAL. The reloader is then free to choose any OAL between Max and Min to become the actual working OAL. In most cases, the difference between Max and Min is much greater than that shown here, and so the reloader has more choice. Whatever OAL is chosen, all 3 OALs should be recorded in the reloading notebook for future reference.

With an OAL like 1.160" you can use any load for 200gr jacketed that is equal to or shorter than. So the load for the 1.155" from Hodgdon will work nicely. Can you follow all that? I hope so. Now you are armed with EXACT knowledge of your firearm and don't have to guess any longer.

Ask questions. We're here to help.

Hope this gets you on your way.  ;)
Title: Re: 200 grain Hornady XTP loads for my CZ97
Post by: kerncat on October 17, 2010, 07:55:44 AM
Thanks Mr. Wobbly.  Great post and thank you for that.  I used to do almost the exact same thing with rifle ammo years ago.  Since I'm unable to post a picture on the reply I'll post a visual that I have used and would really appreciate any comments as it appears to be somewhat the same and I think the first "picture" would depict the headspace measurement where the 0.015 has not been allowed for as yet.  Am I confusing it? 

You do not understand. The object of Max OAL is to make sure that the bullet never comes into contact with the barrel's rifling. Normally 0.005" would do fine for this, but there are additional manufacturing tolerances to take into account. Very few reloaders have +/-.000" tolerance on their OAL over 500 pistol cartridges. Therefore, because OALs will vary, we have to build-in extra clearance. Then when an OAL runs longer on 1 or 2 cartridges, every bullet within a batch still has the necessary clearance. This is required, not only for performance, but also for safety reasons as well.

I just loaded some 38 Specials that have a max length of 1.550, a minimum of 1.415 for that bullet and load and I set them up at 1.470 for my application.  I would think that as long as I stay over the minimum case length and under the measured length minus at least the 0.015 I'd be good to go.  Am I on the right track?  Thanks again.
Title: Re: 200 grain Hornady XTP loads for my CZ97
Post by: Wobbly on October 17, 2010, 12:58:10 PM
Mr Cat -
Your knowledge of revolver ammo has very little relevance when discussing auto pistol rounds.
? Owing to the design, a revolver round most always uses a roll crimp into the groove (aka cannelure) provided. The placement of the groove therefore determines the OAL. Conversely, you usually don't move the OAL on a revolver round.
? There are no magazine lips, feed ramps, failure-to-feed issues, etc with a revolver.
? You have to work really hard to loose cartridge cases when shooting a revolver in the woods. Whereas with an auto pistol, you are lucky to find 1 in 20.  ;D

Therefore we have to "grow" in our knowledge of various auto pistol reloading issues.

? My suggested 0.015" is the MINIMUM setback, just to keep the bullet out of the rifling. You can always use more. In fact, if your press turns out ammo with huge variations in OAL, then you most definitely SHOULD use a greater set-back. The suggested 0.015" works fairly well for people who can maintain a batch of ammo which has a variation of no more than 0.006" across a batch of 50 rounds. If you oil the press, use the same speed and force on each press operation, then MOST people can hold 0.006" (that is +/-.003") over 50 rounds. However if you drink coffee and listen to Talk-Radio while reloading, and the discussion of the latest Congressional spending spree, loss of freedom, or Pelosi quote has your blood boiling, then your OALs could vary as much as 1.000 to 2.000". (Moderator: This is an example, not a political rant.) So you need to check your work.

? To post a picture, you need a web hosting service for photos. I use Google Photos becasue it's Free and can be tied to your Google password. Upload the photo to Google Photo. Open the photo in Google Photo to full size. Right-click the photo and "copy the image location". Then go into your post, and click the icon that looks like the Mona Lisa, then right-click again to "paste" the image location. The first time will take you 30 minutes. The second time will take you 20 seconds.

? Ramp angles are more of a 1911 issue. Modern auto loaders tilt the barrel much more than Browning did in 1903, and therefore most of the problems have disappeared. But not completely. The 45ACP is still a whopper of a bullet to feed, but CZ and others have generally got it worked out.

? I'll take a full post to answer that last question. Others feel free to chime in. This ain't my forum, and I'm no expert.  ;D

Title: Re: 200 grain Hornady XTP loads for my CZ97
Post by: Wobbly on October 17, 2010, 01:46:16 PM
Mr Kern -
? To start with, you've got to realize that each auto-pistol maker makes their barrel and chamber slightly different from everyone else. That affects ammo feeding, types of ammo, etc that the gun can shoot.... and to a great deal the accuracy that results from shooting said ammo. All these barrels meet SAAMI specs and yet most all are radically different. The following cartoon will try to graphically explain...


? Secondly, when bullet makers tell us, use XYZ length as an OAL what they are saying is, "This is what we used and the results we got." They are NOT saying this is the "perfect OAL", or that their OAL will work in every gun, or that they think this is some kind of whiz-bang, never-fail, always-feed-correctly dimension. Far from it. If you'll read your manual you'll discover that this ammo testing takes place in "test barrels". This is a huge block of steel, bolted to a table top, with all sorts of meters and gauges hanging off of it. It is a "gun", but it is NOT a pistol, and it is MOST DEFINITELY not auto loading. It's a single shot hunk of steel, such as pictured below.


So anyone who thinks that the Hornady, Speer, or Hodgdon manual is suggesting that you use a certain OAL because it will feed well in your pistol is way, way off base. They never said that. They only said "It worked for us, now go make it work for you."

? Now certainly, those manual writers chose an OAL that will fit "popular pistols" and work out good for a lot of people. The problem is, they didn't tell us which popular pistol they chose. The second problem is, the most popular pistol out there has such huge dimensions on their chambers that you can almost shoot 50 BMG in their 9mm model.  ;D

? At the opposite end of the spectrum is the CZ and Springfield XD models. These are made in eastern Europe where they still respect fine pistols and craftsmanship. One of the ways CZ achieves such incredible accuracy is by shortening the "freebore"; that part of the bore in front of the chamber that has no rifling. This section is also known as the "leade". This is not usually an issue with RN bullets, and generally everyone is happy.

However when we use a bullet like the Hornady XTP that brings the major diameter well out in front of the cartridge case mouth, this diameter can stick out far enough to strike the rifling. That is, the short freebore means we have to use a shorter OAL than most reloading manuals show. This because most reloading manuals are NOT written with the CZ and the Springfield XD series in mind. Follow? Luckily for us, as per above, there is nothing "sacred" about OAL on an auto cartridge and we can remedy this.

? So when you start this adventure of "what OAL should I use", I can only say that it's a bit like driving. That is, if you stay between the boundaries, then you'll be fairly safe. So where are the boundaries? One is the MAXIMUM usable OAL (as discussed in the post above), which can be arrived at with the telescoping "test cartridge".

The other boundary is the MINIMUM safe OAL which is published load data with the shortest OAL you can find. There are also concerns about good cartridge feeding and maximum bullet seating depth when using extremely short OALs. But generally speaking, novice reloaders shouldn't use an OAL shorter than given in published load information.

? So we have our OAL picked out, the next thing we need is a powder load to match that OAL. In any gun the one thing we're fighting is chamber pressure. We definitely want to keep it in the safe range. Two main things make up chamber pressure: volume under the bullet (a function of OAL), and amount of powder. For the same bullet with the same bullet speed, the rule is: as the OAL gets shorter we reduce the powder. This handy chart shows generally what's going on....


? We always want to start with a published load. ALWAYS. Every load you fire should be based on something published. There are too many authoritative sources available through the internet to use a load from an "internet buddy". This is why reloaders generally build a library, to have numerous published sources they can depend upon.

? So let's say our chosen OAL is 1.247" for a 190gr jacketed bullet and we find a load on-line at the Hodgdon web site with an OAL of 1.235" for a 190gr jacketed bullet. We can use it because the bullet construction and the bullet weights match. We can also use the load because they have quoted a shorter OAL. If we use the shorter load but stay at the longer cartridge length, then our pressure will be lower. That's right from the chart. Follow? You can always go for a longer OAL (within reason) on a published load; never shorter without reducing the powder.

My personal preference would be to load at 1.240". In that way a) my pressure is a tad lower, b) my bullet is .007" further from the rifling, and c) 1.240" is a number that's much easier to read on a caliper. That's killing 3 files with one swat, so to speak. In actuality, it's being smart and thinking safe. In reloading you always want to err toward safety.

? So what happens if the shortest publish load you can find is not short enough? For very small changes in OAL, you can proportion the load. This will call for some 6th grade Algegra, which if you are not up to it can lead to a very big mistake. I think it best to take those on a case-by-case basis. In other words, we'll cross that bridge IF we get there.  ;D

? Then comes the 5-10 rounds starting at the lowest possible load. Depending on the load spread, you might want to work your way upward in 0.1gr or 0.2gr increments. This is all the usual stuff you would do with any load.

? AND AS ALWAYS... you are making notes in your reloading notebook so you can come back to this load, know where you got the load, how it shoots, etc, etc should you be lucky enough to go on vacation for 2 weeks. So write it down!

Hope this helps!  ;)
Title: Re: 200 grain Hornady XTP loads for my CZ97
Post by: kerncat on October 17, 2010, 02:39:23 PM
I sent you a couple of P/M's which you have answered here and man is it a detailed explanation of the mechanics of the whole process.  Now let's say because of the CZ tightness of spec the bullet has to seat back to obtain the gap from the projectile to the lands and grooves in the barrel for the particular load and powder we are using.  As we move the bullet back we increase pressure, correct?   

If so, how do we determine at which point we are into a danger zone with pressure?  Is it possible that some bullets will not be usable in the CZ bore unless we reduce the charge so much that some other bullet choice would serve us better? 

Like the example I cited... If I am looking to repower a Mustang and would like a 512 aluminum race engine.  It may be a great exercise in mechanical ability to accomplish the repower, but might be a better choice to start with something that is more suitable.  If the XTP is difficult to use in the CZ, would it be a better choice to find a bullet that is more CZ friendly?
Title: Re: 200 grain Hornady XTP loads for my CZ97
Post by: Wobbly on October 17, 2010, 03:40:21 PM
Bob Cat -
We were both writing at the same time. You asked questions that I answered on further down into the post. Re-read the earlier post.

? I shoot the XTP in my 9mm CZ with great satisfaction. You can do the same with your 45 CZ. The XTP is a "concern"; it is NOT a "problem". You have merely hit a speed bump on the road to reloading; you have not encountered a 127 car pile-up, with 2 police departments, 3 life-flight helicopters, and 16 fire trucks.

? Yes, there are some bullets that are such a PIA that I prefer to not use them in the CZ. Not every bullet offered for sale can be used in every gun. The XTP does need special care, but it is NOT one of those in the excluded group.

? Yes, you are correct. As you reduce the OAL you would use less powder to get the same chamber pressure. How do we find this new lower powder load? Simple: We look it up. We don't guess. We don't take chances. We look it up.

? It all starts with YOU finding the MAX usable OAL for the XTP in YOUR barrel. Sorry, but no one else on Earth can tell us that number. YOU have to do that part of the work.

? When we know the MAX usable OAL, then we can use other known facts and rules to extrapolate new information. In that way we'll move from fact to fact. The whole process is based on facts and rules. That's the only way to do it safely.

? Yes, this is a bit like an engine swap, but it is NOT like "shoehorning" a 512 engine into a Mustang. It's more like we're taking out the strait I-6 and installing a V-6. I do this process on every new-to-me bullet I load. The first time will require about 15 minutes; all subsequent attempts will take less than 3. It sounds complicated, but it takes far more effort to fall off a bar stool.  ;D

? If you are new to CZs and/or new to reloading, then it it ALWAYS advisable to start with plated or jacketed FMJ Round Nose bullets. RN bullets are simply easier to work with and usually allow a much wider range of OAL. After you reload several hundred RN, then you'll be much more familiar with the process and equipment. Learn to walk before you try running.

Hope this helps.  ;)
Title: Re: 200 grain Hornady XTP loads for my CZ97
Post by: kerncat on October 17, 2010, 04:16:04 PM
Thanks.  I'll send along the spec for my barrel when I get it done.  I understand what you are saying and plan to follow your input closely.  I also understand the CZ is a "challenge" with certain bullets.  I also point out that my interest in the XTP is without the proper consideration to what might be involved with the CZ (or possibly other pistols), so I may have gotten the cart before the horse. 

Hopefully I'll find the loading involved with the XTP is in fact a bump in the road and not a big pileup.  Thanks again for tolerating a new person that just can't seem to find anything in the loading manuals that indicate it's OK to play with bullet seating depths, even though I'm sure it is done every day by experienced loaders.
Title: Re: 200 grain Hornady XTP loads for my CZ97
Post by: Wobbly on October 17, 2010, 08:44:57 PM
Mr Cat -
You are far, far closer than you think. When you do the "push test" your numbers may land right on top of the Hornady numbers out of their manual. So with a CZ you never know, but you always want to check.

When your bullets arrive, do the push test about 10 times with 2 or 3 different test cartridges. Then let us know the number that keeps popping up. There may be no issue at all.

Title: Re: How to determine Max OAL for a CZ Pistol
Post by: Wobbly on September 15, 2018, 08:25:11 PM
Further Thoughts and Notes on This Subject

? Since this conversation took place in 2010, it has come to light that it's really only the 9mm versions of the CZ pistol that need this extra effort. The 40S&W and 45ACP chambers allow ample leade, and therefore issues with OAL are generally not a concern. Still, there is no harm in knowing exactly how your bullet is interfacing with the barrel.

? This issue with the 9mm CZ pistol chambers arises for the American reloader simply becasue no other bullet is available to civilians in Europe, other than the round nose FMJ. So the Czechs cut their chambers for the only bullet available to them. If you are new to reloading for the 9mm CZ pistols, then starting with the round nose FMJ is highly encouraged simply because it will make things easier on you. "Walk before you run" type thinking.

? By a wide margin, the Lyman Reloading Manual is the preferred book for load data. One reason is that Lyman does not make components for reloading, so their data shows no bias toward the different makers. Also, the Lyman is more complete. Lyman goes through the trouble to test almost every caliber in common use, whereas (for instance) if Sierra doesn't make a Makarov diameter bullet, then no load data for the 9x18 Makarov will be found in their manual.

However, there are certain times when we prefer manuals other than the Lyman. If you load premier bullets, such as the Hornady XTP, Speer Gold Dot, or Sierra Match King, then those manufacturer's manuals can give you product specific information that can be invaluable.