COL Science?

[iamdb]

I am having a had time under standing the variations in COL. I am about to start loading for 9mm. My lyman 49 has no data for 124.gr fmj and I cannot not find "factory data" on titegroup with 124 fmj. on he internet. I have found most people seem to load 4.1gn-4.3gn but no COL is listed. I have seen "factory data" recommend lenghts for fmj from 1.005" to 1.169"

Is there some sort of science or formula to figure out the COL for a given load?

[primerman]

Where did you find that 1.005 number? Also what is the bullet shape of the 124g that you want to load?

[iamdb]

FMJ is the shape I want to load. I got the 1.005" from the lyman 49th for a 95gr FMJ. They have a 125gr Jacketed HP seated to 1.075". But no 124gr FMJ data.

[Zach W.]

Book oal is just what worked for them.

Ultimately, your oal will be determined by things like fits in magazine, fits in chamber, distance you want ogive off the rifling (rifles), or by simply seating to the cannuler so the crimp can be rolled in.

Edit: FMJ is not a shape. Round nose, cone, wadcutter, semi-wadcutter, hollow point, spitzer, semi spitzer... these are examples of bullet shapes.

[NWPilgrim]

THe reason you see such variation, especially for 9mm Luger, is that the chamber is designed for a very long tapered FMJ bullet. If you load a similar bullet then you can load out toward the max COL.

The issue is when you load a blunt nose bullet such as a HP or FP. If you load them long like that the bullet tip will wedge into the pointy end of the chamber. I just loaded some new Berry's 124 gr HP ulelts and the max length I could get with easy chamber was 1.070", where as with lead round nose I can easily load out to 1.150" (COL max is 1.169").

I was playing around with QuickLoad and various COL, and it did not seem to make difference in pressure from 1.150" to 1.110", but under 1.100" the pressure started to rise significantly for each 0.010" decrease.

[iamdb]

but under 1.100" the pressure started to rise significantly for each 0.010" decrease.

Thanks. That's exactly the kind of info I am interested in. The bullet shape I will be using is round nose. I picked up some Zero 124gr today. I also got WSF and Titegroup. I have good load data for the WSF but could not find it for the titegroup. I am under the impression TG can pressure spike fairly quickly while the WSF seems unaffected by COL.

[iamdb]

Another question, do you start to lose velocity as the OAL increases by .010"?

[BDS-THR]

Originally Posted by iamdb

I am under the impression TG can pressure spike fairly quickly while the WSF seems unaffected by COL.

WSF and other pistol powders WILL be affected by COL/OAL/COAL! Yes, Titegroup can pressure spike VERY quickly. I do not recommend TG to new reloaders and suggest more moderately fast burning pistol powder like W231/HP-38 (same powder) instead, especially for producing accurate target loads. WSF is my favorite powder for producing full-power loads.

Is there some sort of science or formula to figure out the COL for a given load?

You do not need to use the OAL listed on published load data as often test barrel fixtures and not real pistols are used to measure chamber pressures. Using published OALs WILL NOT ensure reliable feeding/chambering of finished rounds in your pistols.

Determining OAL should not be a guessing game and I use the following process for semi-auto loads whenever I use a new bullet:

1. Make sure resized cases drop freely into the barrel chamber. If not, adjust the resizing die to ensure the cases are resized full-length and fall in freely into the chamber.

2. Determine Max OAL - Make a dummy round (no powder/primer) and perform the barrel drop test with the barrel out of the pistol starting with the SAAMI max OAL until the dummy round falls into the chamber freely with a "plonk" and spin without hitting the start of rifling.

3. Next determine Ideal OAL - Load the Max OAL dummy round in the magazine and manually release the slide without riding the slide with your hand. Incrementally decrease the OAL until dummy round reliably feed/chamber. Depending on the pistol/barrel used, Ideal OAL that will work reliably will vary. If you are reloading for multiple pistols, use the Ideal OAL that will work reliably in all the pistols.

Once you determined the OAL that will work with your pistol/barrel/magazine, THEN you can conduct a full powder work up from published start charge to max charge (If only max powder charge is listed, then use 10% reduction as your start charge - If 5.0 gr is listed as max, then use 4.5 gr as start charge). Note: If I am using shorter OAL than published OAL, I'll reduce my start/max charges by .2-.3 gr.

I usually load about 10 rounds of each .1-.2 gr increments of power charge to determine the powder charge that reliably cycle the slide and produce accurate shot groups.

[BDS-THR]

Originally Posted by iamdb

But no 124gr FMJ data.

You can use 125 gr FMJ load data for 124 gr FMJ bullet (most jacketed bullet will vary by 1 gr anyways. ).

Here's load data from Hodgdon arranged by powder burn rate (top/faster - bottom/slower) - http://data.hodgdon.com/cartridge_load.asp

125 gr FMJ Hodgdon Clays OAL 1.090" Start 3.5 gr (1010 fps) 28,000 CUP - Max 3.7 gr (1056 fps) 32,500 CUP

125 gr FMJ IMR 700-X OAL 1.090" Start 3.0 gr (845 fps) 21,600 PSI - Max 3.6 gr (1007 fps) 31,000 PSI

125 gr FMJ Hodgdon Titegroup OAL 1.090" Start 4.1 gr (1069 fps) 27,300 CUP - Max 4.4 gr (1136 fps) 30,600 CUP

125 gr FMJ IMR PB OAL 1.090" Start 3.2 gr (887 fps) 25,600 PSI - Max 3.6 gr (974 fps) 33,500 PSI

125 gr FMJ IMR SR 7625 OAL 1.090" Start 4.1 gr (996 fps) 28,900 PSI - Max 4.6 gr (1074 fps) 33,700 PSI

125 gr FMJ Win 231/Hodgdon HP-38 OAL 1.090" Start 4.4 gr (1009 fps) 24,600 CUP - Max 4.8 gr (1088 fps) 28,800 CUP

125 gr FMJ Hodgdon Universal OAL 1.090" Start 4.3 gr (1031 fps) 26,900 CUP - Max 4.9 gr (1118 fps) 30,600 CUP

124 gr FMJ Winchester WSF OAL 1.169" Start 4.7 gr (1015 fps) 27,700 PSI - Max 5.3 gr (1115 fps) 32,700 PSI

125 gr FMJ IMR SR 4756 OAL 1.090" Start 4.5 gr (973 fps) 25,700 PSI - Max 4.9 gr (1037 fps) 28,700 PSI

125 gr FMJ Hodgdon HS-6 OAL 1.090" Start 6.4 gr (1131 fps) 25,600 CUP - Max 6.8 gr (1169 fps) 27,100 CUP

125 gr FMJ Winchester AutoComp OAL 1.090" Start 4.7 gr (1055 fps) 28,900 PSI - Max 5.2 gr (1120 fps) 33,300 PSI

125 gr FMJ Hodgdon Longshot OAL 1.090" Start 4.7 gr (1022 fps) 28,100 PSI - Max 5.7 gr (1162 fps) 33,400 PSI

[NWPilgrim]

This is just an example of load data showing QuickLoad's estimation of velocity changes with change in COL. EXAMPLE only.

9mm Luger, 124 gr FMJ, TiteGroup powder, 4.0" barrel, 3.40 gr

You can see the velocity does not change very much, but pressure DOES.

COL = 1.100"

Grains FPS PSI

3.40 993 32273 ! Near Maximum !

COL = 1.110
3.40 984 30604 ! Near Maximum !

COL = 1.120"
3.40 976 29108

COL = 1.130"
3.40 968 27760

COL = 1.140"
3.40 961 26539

COL = 1.150"
3.40 953 25427

COL = 1.160"
3.40 946 24410

Now a similar example going the other way using 4.0 gr Titegroup As you can see it quickly becomes a dangerous load that should NOT be used, according to the QuickLoad program.

COL = 1.160"
4.00 1053 33866 ! Near Maximum !

COL = 1.150"
4.00 1061 35418 !DANGEROUS LOAD-DO NOT USE!

COL = 1.140"
4.00 1069 37127 !DANGEROUS LOAD-DO NOT USE!

You get the idea. Below COL = 1.160" and you start exceeding the SAAMI pressure limit for 9mm Luger of 35,000 PSI.

[Edward429451]

If I don't have COL data for a new bullet, I seat it until it looks good and then go compare lengths with similar bullets even if they are not exact, it will get you in the ballpark. Trust your eyes to tell you, looks long...looks short.

I know that may sound absurd, but your eyes are capable of more precision than you may think. Seat one trial and error until it looks good. Now try it in your Mag. Now look at the bullet in the Mag, How does it look for length in the Mag? Good? Record it and load. Look too short? Pull it and start over.

I was loading 45 ACP for years without a caliper. I just kept bumping them down until the barely fit in the Mag.

[primerman]

YOur lucky Pilgrim, I had to go lower than that to get my Berry's 124g HP's to fit my Walther PPS. (I was not using Titegroup for that load) That is why I finally gave up on that bullet and moved on to other Berry's 9mm bullets. Maybe someday I'll get a gun that is chambered a little different and finish the 600 bullets I have left over.

[scsov509]

I was loading 45 ACP for years without a caliper.

The difference is that 45 is by comparison a large volume case and low pressure round. I would not recommend you load 9mm without making precise measurements, especially not with a faster powder like you're describing. The combination of a low volume case, high pressure round, and fast powder can get dangerous in a whole hurry.

[NWPilgrim]

YOur lucky Pilgrim, I had to go lower than that to get my Berry's 124g HP's to fit my Walther PPS.

Yes, I was surprised how blunt the Berry's 124 gr HP is. It may be a great design for the .357 SIG except I don't believe the plated bullets are rated for its velocity. I have some Win Ranger and Federal HS hollowpoints and they are all loaded to 1.110" or so. I agree with you primerman that next time I'll get a different bullet shape either from Berry's or elsewhere. I like the berry's bullets in general ut this particular weight one is oddly not designed well for the 9mm Luger.

[iamdb]

Thanks gentlemen! You guys have great information. I think I have a pretty good understanding now. I printed out this thread and put it in my manual.

[Mac Sidewinder]

This is the type of conflicting information (to me at least) that I find very confusing:

BDS-THR printed a listing from Hodgdon as:

125 gr FMJ Hodgdon Titegroup OAL 1.090" Start 4.1 gr (1069 fps) 27,300 CUP - Max 4.4 gr (1136 fps) 30,600 CUP

But NWPilgrim listed this from a program:

Now a similar example going the other way using 4.0 gr Titegroup As you can see it quickly becomes a dangerous load that should NOT be used, according to the QuickLoad program.

COL = 1.160"
4.00 1053 33866 ! Near Maximum !

COL = 1.150"
4.00 1061 35418 !DANGEROUS LOAD-DO NOT USE!

COL = 1.140"
4.00 1069 37127 !DANGEROUS LOAD-DO NOT USE!

You get the idea. Below COL = 1.160" and you start exceeding the SAAMI pressure limit for 9mm Luger of 35,000 PSI.

The first example from Hodgdon's own site lists a higher load and a shorter OAL - wouldn't that produce even higher pressures, or am I missing something? Please help me learn - I am just starting out.

Or is COL and OAL not the same thing? If not how do they compare to each other?

Mac

[NWPilgrim]

Mac, that kind of difference in listings is not unsual nor is it always the case.

Sometimes you will find several load tales that are pretty much all the same. So you can be pretty confident it is well proven out combination, and possibly a very well tempered powder. That is one thing I like about powders such as Unique and H4895 is that they seem to behave very consistently and change gradually with any change in loading factors.

Other times you can get wide variations for a certain combination from different tables. That is a warning to me that one of them may be a misprint (I have found a few of those in my years of reloading), or the cartridge or that particular powder is erratic or "spiky".

When I see these wide variations I would consider which of them are from the actual manufacturers, and also take extra caution in figuring my start loads and test progression. QuickLoad is generally very close to many manuals' load tables but it is ultimately a calculated value rather than an observed value from testing.

Personally, I would check yet another source like Sierra, Speer, or Hornady to see if they are more like Hodgdon or QuickLoad. I also try to gauge it against other similar listing. In this example, this load does in fact fall in between loads Hodgdon lists for TiteGroup and 115 gr and 147 gr bullets so it probably is accurate results from the Hodgdon testing. I would tend to favor the powder mfg tables.

Either way, I would take the QL data as a warning to maybe start even below the Hodgdon start load and work up very slowly.

[Mac Sidewinder]

Thanks NWPilgrim for the info. Since bullet seating depth affects pressure, how do you figure out a starting point when you can't find the exact bullet for a certain load? Such as you can match the wieght but not the specific brand of bullet? Do you find another bullet listing that matches the type and dimensions and go off that table for the seating depth? You can't just go off OAL and call it good right since different length bullets will be seated to a different depth affecting chamber pressures.

Also is COL and OAL used interchangably?

Mac

[NWPilgrim]

Yes, COL and OAL are the same. COL - Cartridge Overall Length and OAL - OverAll Length (cartridge is implied).

Personally I just use the given data if I am using more or less generic bullets. For example, I may be loading Remington FMJ bullets but use the Speer or Hornady FMJ data. I rarely load to the listed max powder weights, so a .020" difference is not big deal. And of course I start at the start loads or below and work up test loads incrementally. I do try to find data for the same weight, shape and construction of bullet such as Lead Round Nose, Lead Semi-Wadcutter, jacketed hollowpoint, etc.

If I am loading an unusual bullet such as a non-lead bullet, polymer tipped, etc. the I will buy the bullet manufacturer's loading manual. I have several manuls and and am on the next edition of most: Hodgdon (they use to publish one before going mostly online), Speer, Hornady, Lyman, Nosler, Accurate, LaserCast, Lee. Waiting for Sierra to come out with an updated one, too.

A couple of years ago I broke down and bought the QuickLoad program so I could have a more universal reference and to fill in the gaps of the other manuals. I always run a load through QuickLoad to account for specific bullet and COL, and then get a table of pressures and velocities for a specific powder and barrel length. Then I double check with a couple of manuals or websites like Hodgdon's and Alliant's.