Tweaking a 9mm load...

[Corner Pocket]

I've just now finished up loading the last of some 125 gr LRN for my 9mm. I did some expected tweaks along the way to get this load to where it is. My gun loves them and I really enjoy the accuracy at the range. The bullet length on these lead bullets is .610 inches. I'm setting the OAL at 1.125 inches.

I recently ordered a thousand 125 gr LRN from another company just to give them a try. Upon opening the box and checking the weight of individual bullets, I find that they are indeed 125 gr, but these are a little shorter, measuring .567 inches in length. This surprised me a bit, but the nose of these new bullets is fatter (stubbier) than the previous ones that I've been using, which have a tip that is thinner and with more of a point.

Question: if I set the OAL to 1.125 on these shorter bullets, that is going to alter the chamber pressure, no? I'm not sure what I need to do to compensate, so thought I'd toss out a plea for advice before I make a loading error. Thanks!

Corner Pocket

 

[Galil5.56]

Try working on seating length with these till a proper fit is found. It is impossible for anyone to say exactly what will work best for your pistol, and simply knowing the bullets total length can not tell us what the proper OAL for you is. 9mm bullets with a long full diameter shank/short "nose" require a shorter OAL than many other types.

I seat Lee 124 TC bullets to 1.050"-1.070", Lee 125 RN to 1.10", Lyman 356402 clones at 1.135". The Lee 124 has the shortest nose/longest shank, the Lyman the longest nose/shortest shank. Looking at many different seated bullets, it's amazing how similar the actual amount of "seated bullet" is in the case, regardless of OAL.

 

[RidgwayCO]

Your .610" bullet seated to a COL of 1.125 results in a bullet seating depth of .235" (assuming your 9mm Luger cases are .750" long). Duplicating this seating depth with your new .567" bullet would result in a new COL of 1.082". Theoretically, the pressure inside the case would be the same, and therefore the resulting velocity should be very close to your previously developed load.

Now whether this new round with a shorter COL feeds properly, or is acceptably accurate, can only be determined by testing in your pistol.

Alternatively, seating your .567" bullet to a COL of 1.125" results in a seating depth of .192". This gives more room for the powder to burn, resulting in slightly less pressure and therefore slightly less velocity. But it may be necessary if the shorter COL doesn't feed well.

Also remember, the new nose profile may not feed as well as the more pointed profile of your first bullets. I've not seen this to be a problem with round nose bullets in the 9mm, but you can never really be sure until you test.

 

[Walkalong]

Because they are both 125 Gr round nosed bullets, just different profiles, the shorter one will probably need to be seated a bit shorter than the longer one that feeds fine at the 1.125 O.A.L.. Unles you are using a flat stem in your seater, try seating the shorter bullet with the seater set the same as for the longer bullet. Use that O.A.L. to start at.

 

[Corner Pocket]

Gentlemen, I greatly appreciate your good input. I've just now loaded up seven rounds of the new bullets to an OAL of 1.100 and look forward to sending them downrange this coming Monday afternoon. I'll drop back by here and give a report as to what the verdict is... Thank you!

Edit: Walkalong, I didn't see your post before I replied. I'll surely keep what you've said in mind if I find that these set at 1.100 don't feed properly...

CP
'rapt with anticipation!'

 

[Walkalong]

Go ahead and try that with 10 or 12. Compare the 0.A.L. to your 1.100, and then take them with you as well.

 

[zxcvbob]

Ridgeway already hit all the points I was gonna make. So I'll just lamely say "+1" cuz he got everything right.

 

[rfwobbly]

Mr Pocket -
I think you've gotten some great feedback here. As others have said, theoretically you would simply seat the bullet .043" deeper (see my diagram HERE), but that will put you well under 1.100" OAL, which is a dimension I try to stay away from.

Somewhere around 1.100" FTF issues start showing up. It depends on your gun, your mag, and the nose shape of the new bullet. So only you can verify if it will work by firing several hundred rounds.

The other option is to stay at 1.125" and add 0.1gr more powder as an additional trial.

Hope this helps!

 

[Galil5.56]

I've just now loaded up seven rounds of the new bullets to an OAL of 1.100 and look forward to sending them downrange this coming Monday afternoon.

Did you function test them by dropping the rounds into a clean chamber to make sure they fully seat easily w/o running into the leade? As I said, anyone who thinks they can even remotely "nail" optimal OAL w/o seeing the cast bullet in question can't, and even when seen, it's hard because of a lot of other variables... CZ's have short leades, Walther's long, etc, etc.

I gave OAL's as an example of how in my situation, a bullet of almost identical weights need very different OAL's by virtue of style/design but the shank length inside the case is very similar regardless of OAL. Try loading Lee 124 TL TC style bullets to 1.135", and see how they chamber... They will, with the help of a hammer in any 9mm I have tried.

 

[rfwobbly]

Did you function test them by dropping the rounds into a clean chamber to make sure they fully seat easily w/o running into the leade?

This is very good advice. You haven't told us the gun you use and all gun chambers are different. If I was going through the exact same bullet manufacturer swap as you with my CZ I'd be forced to recon with the very short freebore and start from scratch.

The advice we've given you is highly generalized based on your highly nebulous input. Believe me, there's a lot more to this with some guns than simply buying today's cheapest 125gr bullet on the spot market.

 

[Corner Pocket]

Thanks again, folks.

Galil5.56, I did try them in a max. cartridge gauge as I loaded them up. They seemed to work very well in that. At mention of what you have suggested, I dropped them into the chamber of my new Stoeger Cougar 8000 (clone of the former Beretta Cougar 8000), and they look like they fit exactly like some Blazer Brass factory rounds that I have successfully shot in this gun in the past.

Rfwobbly, my sincere apologies for not providing adequate information. I can see that there is a lot to this, and I'm anxious to learn from you and others who have been down this same road...

Believe me, folks. I'm not taking this lightly at all. I'm open to any and all advice that may be offered. I'm appreciative to all who respond.

CP

 

[Galil5.56]

A case length gage will not tell you if your rounds bullets are seated properly with regard to proper leade to bullet relationship. It will tell you if your length is within the SAAMI max, case diameter is OK, etc... For me, I only use the barrel to tell me all I need.

As an FYI, a lot of Beretta, SIG, Walther, and Browning 9mm barrels have groove diameters of .357" plus. My Beretta mics .3572", and I use .358", or even .359" cast bullets. After you get the hang of things, the next aspect I would look at is proper/optimal diameter... It can really help with accuracy and leading problems if they exist, and is the first thing I look at when these problems arise.

 

[RidgwayCO]

CP, if your Stoeger 8000 Cougar is like my Beretta 8000F Cougar, you're lucky. Mine will eat anything up to SAAMI maximum COL (1.169") without so much as a burp. Keep it well-lubed though (especially the slide rails and the nub that runs through the groove in the rotating barrel)...

 

[Corner Pocket]

Rfwobbly, I see where you stated "The other option is to stay at 1.125" and add 0.1gr more powder as an additional trial." I like that idea and have just now put a few rounds together with those parameters being observed. I look forward to seeing how both these and the shorter loads perform when I feed them to my Cougar 8000 next Monday. Thanks, much!

RidgwayCO, maybe I will be as lucky as you.

Corner Pocket

 

[rfwobbly]

Let's be sure now.....

Galil: A case length gage will not tell you if your rounds bullets are seated properly with regard to proper leade to bullet relationship. It will tell you if your length is within the SAAMI max, case diameter is OK, etc... For me, I only use the barrel to tell me all I need.

Mr Pocket -
Well this longer cartridge with the new bullet is where you're going to get into trouble.... if there is trouble to get into. As Galil has suggested, a cartridge gauge is not going to help you. It's the rifling the nose of the bullet is going to run into, and this causes the trouble. The rifling is entirely missing from a cartridge gauge, so it won't help. And the rifling starts at different distances from the chamber on guns made by different manufacturers. So you must test your new round in the barrel you intend to use them in.

The attached graphic shows what I'm talking about. This is a rare but persistent issue. Most pistols made in the US have a generous leade or freebore, and this is not an issue. But other pistols from Europe (notably CZ) do have this issue, so you have to use the exact same barrel as your bullet test gauge.

A 9mm, like the 40 and 45ACP, headspaces on the mouth of the case. If you can drop the bullet all the way into a clean chamber, and the bullet will spin freely, then you are OK. If the bullet does not go all the way in, OR if the bullet does not spin freely, then the bullet is being interfered with by the rifling. The graphic shows how even at the same OAL how this can easily happen.

How this can help!

 

[Corner Pocket]

Many thanks, rfwobbly, for a very helpful post. Using the barrel of my Cougar 8000 just now to check these new rounds that I've loaded, I get the perception that I'm going to be OK when I pull the trigger on these. I can drop them into the chamber and spin them. (The sound that they make also approximates that of rounds that are known to work fine. I think they would make a different sound if they were bumping against the rifling when dropped in there, no?)

On the heels of that, I just thought of something that I decided to check out. I loaded up a dummy round a moment ago that is purposely seated very shallow. When I drop it into the chamber, it does indeed make a different sound than the "good" rounds, and when the barrel is turned upside down, it did not fall back out. Yes, I'm going to be surprised if these new bullets don't work just fine. Will post back... I'm really looking forward to seeing how these perform at the range!

CP

 

[rfwobbly]

Mr Pocket -
While I applaud your intention to use every means at your disposal to do a really good job, using the sense of "hearing" is not one we usually associate with reloading.

As I said in the last post, if the bullet spins freely, then the mouth of the case is "headspacing" (that is "sitting") on the end of the chamber. In the previous diagram, that would be that little jog you see in the red line right below the arrow leading to the word "barrel". The brass case resting against the steel barrel makes a good bearing, so the cartridge turns freely. If the bullet did not turn, then we could, with almost 100% assurance, correctly assume that the nose of the bullet was tied up in the rifling. So the sense that I want you to use is 1) your "common sense", and 2) your sense of "feel".

The sound could have changed based on any one of numerous variables such as having no powder inside the case, crimp diameter, bullet weight, number of beers, date of last ear washing, heavy breathing from girl friend, etc.

Follow?

At any rate, your freely spinning bullets in your barrel are a good sign. Congrats.

 

[Corner Pocket]

Breaking news! Old man in Texas is thrilled with his Cougar!

Hey there, friends!

I just got back from the range. It was a great time there. My new Cougar really strutted its stuff, as I shot at varying distances from 7 to 15 yards. This gun is tremendous!

I'm delighted to report that the test rounds (with COL of 1.100) were "dead on" and the gun gobbled them right up. This is really nice to see!

The idea of "the sound of the plop" when testing a finished cartridge by dropping it into the barrel it will be fired from (mentioned above), makes a lot of sense to me. (If the bullet touches against the lands, it definitely sounds different.) However, others may not find any value in listening for anything strange. No problem.

Corner Pocket

 

[edSky]

Mr. rfwobbly, Sir,

Thank you for your in-depth and informative posts. I often just lurk and read threads that look like they may in some fashion be related to a question or concern of mine. When you contribute I can be guaranteed that I will either learn something new or reinforce my knowledge of a best practice.

 

[Walkalong]

I'm delighted to report that the test rounds (with COL of 1.100) were "dead on" and the gun gobbled them right up. This is really nice to see!

Congrats. Ain't it sweet.

 

[Corner Pocket]

Forgot to mention that the other group of test rounds (those left set at COL of 1.125 with an extra .1 grain of powder added) were also right where I had hoped to see them. I've loaded up some more and will see about getting them to the range this afternoon.

Hey there, edSky! I join you in heaping accolades upon rfwobbly for his helpful and insightful posts.

CP

 

[rfwobbly]

Thanks guys

Thank you for your in-depth and informative posts.

You're all very welcome.

Shooting a CZ as I do, you either learn this stuff forwards and backwards or you sell the gun. Luckily, I'm a design engineer, so mathematical relationships, and coming up with fool-proof ways to test things you can't actually see is something that I've had years to get very good at doing.

My initial CZ bullet order got me an amazingly good deal on 1000 Zero bullets that wouldn't fit my gun "any which way". I was deeply depressed until some senior reloaders started sharing with me. In the end it called for an all new COL that was not listed in any manual and a proportionalized powder load. Then it all became clear. It was a eureka moment.

So first of all, since I know the feeling well, I hate to see others struggle for a solution. Secondly, this information is not propriety to me. I freely admit, I'm mere hack who's standing on the shoulders of giants.


"…From everyone who has been given much, much will be required;..." Luke 12:48

Have a great day.

 

[RidgwayCO]

Ahh, another Cougar fan. Congratulations!

You can tell people how nice the Cougar feels in your hand, how the rotating barrel absorbs recoil like a sponge, and how accurate they are, but until they actually shoot one, they just don't get it...

 

[Corner Pocket]

Amen to that!

RidgwayCO, you have struck the proverbial pointed object right on its epicenter. I can say without reservation that the Cougar is the most pleasant pistol to fire that I've ever shot. I just can't rave enough about it.

As an added ingredient to my happiness with this newly-acquired Cougar, yesterday afternoon I tried out some more of those reloads set to COL of 1.100 inches. I had one of the best shooting excursions ever with them, putting 30 rounds within a 2.6" circle, shooting freehand at 7 yards. Though no doubt many shooters do much better, this is really good (for me) and makes me even more excited about this Cougar!

CP
'Go cats!'