Chronograph...anyone? (9x18 Mak

[Gregory Gauvin]

CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

I've been using up my supply of hodgdon HS-6 loading some 9x18 Mak. Data for this powder is merely non-existent. The only information I could find was from Hornady which gives a start load of 5.6 grains and a max of 6.2 grains. The old Makarov site which no longer exists did have some people developing loads using HS6, but there is nothing listed in any manual I can find. Those there who have chronographed their loads suggested a 6.1 grain charge should render a 1,000 ft/sec velocity.

Generally, factory 9x18 Mak is running 980 ft/sec or so. I have found American Eagle is very underpowered, and often stove pipes my Mak PM. (I think that was American Eagle with the brass colored primers, the American Eagle with the silver primers functioned 100% - or vice versa). Fiocchi seems to be a bit hotter and runs fine.

Needless to say, I am loading 95 grain Berry plated bullets, using converted 9x19 brass, sized and trimmed, seating OAL to .975" I slowly worked up my loads, from what data I got on the Makarov site, also cross referencing .380 ACP data to to utilize as a safety margin. I worked from 5.8 grains to 6.4 grains. The 5.8 grain charge is "low end", but accurate. 6.1 grains I noted as a "nice load". 6.3 grains I noted as "Works Ok". But I have found, the 6.4 grain charge to be balls on accurate and the best of all my load development. It is a bit "stout", but not abusive. And most accurate of all the other loads I have tested.

My manuals show a OAL of .955" to .965. Loading at .975", I can see why I have gone past Hornady's max load listing, as a longer seating depth increases case capacity and lowers pressures. With a slow powder as HS6 is, a .2 grain increase is not gravely detrimental. No signs of pressure (even though this is a blow back action).

I am curious as to guessing what velocity I may be pushing with this load. If 6.1 grains renders a 1,000 ft/sec velocity, would it be safe to say my 6.4 load is around 1050 ft/sec? Or do you think they may be going more towards 1100 ft/sec? I'm not trying to develop some type of +P load here, I am just very curious as to where I may be. It is my understanding most commericial American loadings of this round are "under powered".

[Unclenick]

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CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

The maximum COL for the 9 mm Makarov is 25 mm, or 0.984". All it takes is the right bullet nose shape to be able to use that full COL and still feed reliably, but some, like JHPs, have a more blunt shape and cannot be used that long.

Two different methods based on QuickLOAD's data for HS-6 suggest that if 6.1 grains gives you 1000 fps, then your load will get 1048 fps or 1057 fps. That's an average of 1052.5 fps. So 1050 is not a bad estimate. QL also says ballistic efficiency of this slowish pistol powder is terrible in your chambering and barrel length, with 25-30% pushed out the barrel unburned (again, depending on assumptions). That's why this powder is a good fireball maker. You ought to be able to work loads up with something faster that gives you the same or close to the same performance and pressure with less charge weight. QuickLOAD suggests Vihtavuori N330 is the best candidate, getting close to the same pressure and velocity at about 4.7 grains, and burning is about 94% complete inside the barrel.

[Gregory Gauvin]

Thank you very much. My manual lists a max OAL for the 9x18 as .982", although I have also read the max to be .984". I have found no traces of unburned powered using the 6.4 load. I did have traces of unburned powdered with the 5.8 load.

Most factory loads I have measured have an OAL of .970". Granted I am forming cases from 9x19, sized and trimmed, after fire forming I would suspect the cases to shorten after resizing and I will have to readjust my seating depth. I chose to seat them at .975" because I have measured the bullets and they do vary .002". For reliability sake, a round in excess of .984" may not fully go into battery.

This load produces very minimal muzzle flash, so I do suspect most all the powder is being burnt. And do to its accuracy, probably has a small standard deviation.

Case capacity is only .55cc, do you think increasing the OAL by a mere .005" would greatly reduce velocity?

Do you think reducing the charge and decreasing the OAL to .970 may produce a more complete burn?

On a side note, it has been mentioned that 9x19 brass is generally thicker than 9x18 brass. I have measured both 9x19 cases and factory 9x18 cases and have found them to be the same. (mouth side walls .012"). I don't really crimp my loads, factory crimp measures at .988" and that is what I am running. (.364 bullet dia + .012 + .012 = .988"). HS6 is hard to come by now anyways and I have only been able to find IMR 4756 and Red Dot. I hate having to start over and work up a load once I have found my sweet spot. And although HS6 may not be ideal for this cartridge, it runs great in my 9mm, .40, and .45 (granted, it runs best at mid to hot loads). I like having one powder to suit all my needs, and because it is a slow powder, peak pressure generally is not reached until the bullet exists the barrel giving a slight margin of safety. Fast powders, such as Red Dot or Bullseye, intimidate me slightly, as a mere .1 grain increase in charge weight may ruin your day. With the HS6, it is pretty forgiving. I wouldn't push the charge any harder for my Mak PM, but I also have a CZ-82 and it is my understanding these pistols can be loaded somewhat higher. I am unlikely to attempt it.

If you have time, for fun sake, can you run a quickload and find the charge weight with HS6 that would render a 1050 ft/sec velocity and determine what OAL would be needed to accomplish this?

I have always debated as to whether or not (in pistols) if seating death has a large impact on accuracy verses charge weight, or if seating depth is more paramount for reliable feeding.

For the sake of economical loading, I think some may decrease their charge weight and reduce their OAL. I may be old school, but attempting this can cause pressure spikes and dangerous conditions. I generally seat my pistol rounds to their MAX OAL, unless I run into feeding issues. (Example - 230 grain LRN .45 ACP show a max OAL of 1.270", however my pistol will not go into battery at this length. I must run them at 1.250".)

[Gregory Gauvin]

Also, I forgot to add. I am using 95 grain PLATED bullets. Not FMJ. It is my understanding that plated bullets behave more so like lead, then FMJ. Your estimated velocity from quickload based on a FMJ bullet or a plated bullet?

Would it be safe to say, a plated bullet, using my data, with an estimated velocity of 1050 ft/sec if based upon FMJ data, may in fact be pushing near 1100 ft/sec? Or was that calculated? Thanks.

[Unclenick]

CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

Regarding unburned powder, I mis-spoke. I meant to say it doesn't burn inside the bore, though it may or may not keep burning out in the air beyond it. It can also extinguish when the pressure drops. If you are not getting a fireball, then yours may be extinguishing. The way to tell is to lay newpaper down front of the firing line for two or three yards. See if it collects unburned grains. If so, they may be yellow from losing their graphite coating, but if you collect a small pile off the paper and you can light it with a match and it burns like powder, that's what it is.

Good question on the last point. I used plated bullet (Speer RN TMJ) with start pressure lower than a jacketed bullet.

I have now looked in my Speer databook and found they have HS-6 data for that bullet seated to 0.980" COL in their tests. They tested in an East German made Makarov, rather than a standard test barrel. They show HS-6 starting at 5.6 grains and getting 828 fps and have a maximum of 6.3 grains getting 1010 fps, so it is a little lower on velocity than my earlier calculation showed.

(1010 fps – 828 fps) / (6.3 grn – 5.6 grn) = 260 fps/grn of powder over that range.

So, if Speer's fit and case capacity is the same for you, adding 26 fps for 0.1 grains of powder to their measured 1010 fps gets us to 1036 fps for your load of 6.4 grains. So, we were not all that far off, regardless of bullet types involved. Still, this is all guessing as, depending whether your particular gun is looser or tighter than Speer's, there could still be 50 fps difference one way or the other. Only a choronograph will tell you for sure.

One of the funny things that happens in small capacity cases, especially with a slow powder like HS-6, is the primer will often unseat the bullet and jam it into the lands faster than the powder burn builds pressure, so the practical seating depth from the standpoint of pressure is longer than you set the cartridge to when you made it. In that circumstance, seating depth differences do not produce the pressure change predicted by QuickLOAD. You can tell because velocity SD over a chronograph does not change significantly with seating depth. Indeed, I'm sure this phenomenon has protected many a pistol shooter who didn't crimp his bullets well enough to prevent setback on loading.

Bottom line, though, no, 0.005" difference in seating depth doesn't make much difference in pressure or velocity even when primer unseating doesn't happen. It's a smaller change than normal shot-to-shot variation in loads represents.

Edit: Note, too, that the maximum COL given in the CIP drawing I linked to, as with any maximum COL is just to maintain magazine fit compatibility. It's not a ballistic specification because they don't know what bullet you will use. All they know is that if you make cartridges longer they may have trouble fitting and feeding from some magazines. If you can seat longer and not lose adequate grip on the bullet and the cartridge still feeds from your magazine, then there's no problem. Indeed, in the .45 Auto I typically seat bullets out until the cartridge is headspacing on bullet contact with the throat rather than case mouth contact with the end of the chamber. This consistently produces best accuracy for me with cast bullets. The softer plated bullets may like it, too. The only trick is that the bullet nose be blunt enough in shape so it doesn't exceed magazine fit.

[Gregory Gauvin]

Wow. Thanks a bunch! I would like to get myself a chrono one of these days to play around with.

I thought I may be pushing over 1036 ft/sec, because recoil seemed to be somewhat more than factory ammo rated at 1030, or 1050.

I'm wondering if my CZ-82 will find a good accuracy node at a higher velocity. I don't want to beat my pistols, as I felt going over 6.4 grains with my Mak PM was enough.

[Unclenick]

I've had very good group size with a wide range of loads in the .45 Auto just by using the bullet headspacing trick. With one of my match loads it reduced group size by 40%. As to tuning, pistol barrels are shorter and more rigid than rifle barrels, so they don't swing harmonically with the same enthusiasm rifle barrels do. With pistols, it seems like getting consistent recoil operation and motion of the moving parts and good operator trigger control are more key. …And, as I get older, good shooting glasses.

[Gregory Gauvin]

Ok, quick caliber change, if you have the time to play around with quick load. I am loading 155 grain Oregon trail laser cast in .40S&W. AOL 1.135".

Same powder HS-6.

My data books give a start load of 7.1 grains @ 1076 ft/sec and a max of 8.4 grains @ 1198 ft/sec.

My pistol is most accurate at 7.0 grains (lite load).

Then the next most accurate charge is 7.5 grains, followed by 7.9 grains.

How can I guesstimate the velocities for the 7.5 grain and 7.9 grain charges?