OAL Question - Diff. Projectiles, Diff. Lengths (FP vs RNFP)

[BinaryBoris]

Hello all,

I've been reloading for several months now and have successfully loaded just short of 1,000 40S&W Rainier Lead Safe 180g RNFP, using middle-of-the-road load data of 4.9g V340 and ~1.130 OAL. At the range, every round has chambered and gone bang comfortably and without a problem.

I'm about done with my 1,000 count box of RNFP and am ready to move to some FP projectiles. When eyeballing the two projectiles side by side, I thought one looked shorter than the other. As it turns out, the RNFP is 0.612 in length and the FP is 0.602 in length.

Here's my question:

If I am loading successfully with a 0.612 length 180g RNFP @ 1.130 OAL, would the equivalent with a 0.602 length 180g FP (0.010 shorter) be 1.120 OAL (0.010 less)?

Similarly, if I am loading a 180g HP Rainier Lead Safe projectile that happens to be 0.592 length, would the equivalent OAL be 1.110 (0.020 less than the 180g RNFP)?

In other words, if the projectile is shorter, doesn't that mean I subtract from the OAL so that the "inside the brass where the powder goes boom" space is the same?

Obviously I'm not going to forge ahead unless I know 100% that this line of thinking is correct. I enjoy having two working hands.

Thanks in advance for any assistance!

- Boris

[CGT80]

The length doesn't matter nearly as much as the profile of the bullet. The amount of air space in the case will have an effect on the pressure of your load, but you can start at a low charge weight and work up to find the best amount of powder for a particular bullet.

Look carefully at the shape of the nose of the bullet. A tapered nose will be less likely to interfere with the rifling of the barrel than a fat nose. Some barrels are tapered to help with this and others are not. You can have a barrel tapered as well, if needed.

Load up a dummy round with your new bullet and leave it long. Pull the barrel out of your gun and drop the dummy round in the chamber. Push it in with your thumb. Now tip the barrel the other way and see if the round drops out, if you even managed to get the brass all the way down in the chamber. The round may not chamber or you may have marks on the bullet where it engaged the rifling. Seat the bullet a little deeper and see if the round now goes all the way into the chamber and then drops back out. Use one of the rounds of ammo you are currently shooting and see if it clears the chamber easily.

You don't want more crimp than necessary. I prefer to use a separate seating die and crimp die. You just want to straighten out any flare/bell, with the crimp die. Maybe just a tad more crimp if you need to get it to chamber. Too much crimp will break the plating on the bullet or the coating if you ever go to moly/coated bullets. It can also effect the SD numbers on the velocities. If you don't crimp your test rounds, it will not chamber easily and you may think you have the round set too long.

The max length for 40 S&W is 1.135". Loading long is desirable, when possible. It keeps pressure lower and may feed better. You might be able to go longer than that depending on your gun and mag. Some of my ammo is 1.130"-1.140" and some is much shorter. I am shooting a 155 lswc right now and I am at 1.140". The factory barrel of my xd 40 service doesn't have any noticeable taper. My barsto 9mm barrel was tapered by my gunsmith so it is very forgiving.

If the case volume end up being similar for both bullets, and they weigh the same, then your load should be fine. You could start low again and do a few test loads. I always do a ladder test to find out what functions my gun when I switch bullets. I like just enough powder to cycle the gun when I shoot weak hand only. I think I bumped up my last load just a tad as it seemed more accurate. I use my gun for competitions and they don't have a minimum power factor so I aim to keep recoil down and speed up.

I used to shoot copper plated and then I went to jacketed, and now I shoot bear creek moly coated or cast lead. Now, I am also casting my own boolits for many of my guns. Recently, I got into powder coating lead boolits as well. I learned that moly coated and lead work just fine, even for competing, if you know how to load them. My shooting skills are good enough to challenge the local competitors, but I am not winning the matches or going pro. The bullets are not the blame if I don't win. I have run 30-40 thousand rounds of 9 and 40 (my own reloads) through my XD competition pistol, so I have had some time to play with different bullets and loads.

I get in on a local group buy and 40 cal bear creek bullets run around $70 per thousand. Copper plated is fine if the price is good. Lead can be messy, but shoots very well in my pistol, in 40 cal. I do get some leading from factory lead bullets, but it cleans up Ok.

[J-cat]

You can load the 40 longer than 1.135". I load mine to 1.150". I use OAL to tune the load, keeping bullet length in mind. For some reason my Glock likes the longer OAL better.

[BinaryBoris]

Wow thank you for the great information. I'd like to move into local competitions at some point in the near future, but I'm still learning the ropes so to speak.

I read through your entire post and really appreciate the pointers. I guess I'm at "stage one" when it comes to shifting to a new bullet. My main concern above all is safety to myself, followed secondly with safety for my firearm.

If I follow correctly, would you say it's true that if I'm loading a projectile that is .01" shorter that I should simply take .01" off the OAL I was using for the same weight projectile and the same powder load?

Wouldn't this result in the same "case volume"? It would be igniting the same amount of the same type of powder within the same volume and pushing a projectile that is the same weight.

Thanks again!

- Boris

[BinaryBoris]

OK I think I understand what you mean with the process of taking the barrel out and testing the bullets to make sure they don't stick. Basically this is to ensure that the bullet doesn't cause undue friction when being fired or, worse, get stuck?

(Edit: found some great stuff here that looked a lot like what you were talking about http://www.38super.net/Pages/Bullet%...liability.html)

So: #1 make sure I have the same case volume (decrease cartridge OAL at the same rate that the projectile's OAL decreases) and #2 make sure the bullet goes into battery properly.

[Witch Hunter]

First you have to ensure the new bullet will go into battery, I like the plunk test in your barrel method. You may find your OAL is the same. If not, lower your charge and work back up. Make sure to keep good notes for each gun you own.

[BinaryBoris]

OK thanks. I am pretty sure the new bullet will go into battery since it will be .01" shorter. But that said, after I make sure it goes into battery, am I correct in that when loading a bullet that is .01" shorter I should ideally aim for an OAL that is .01" shorter so that the case volume is the same (all other things being equal)?

Thanks.

[CGT80]

I would assume that keeping your powder volume the same with two bullets of the same weight would keep the pressure the same. I would agree that a shorter bullet would have to be seated deeper to keep it the same. You could seat to the same length and have an additional .010" of powder volume. This should decrease your pressure a little. This is assuming you could leave the case overall length the same and get that bullet to fit in your chamber.

When I switched bullet profiles for the same weight, with copper plated bullets, I didn't bother changing the powder charge. I seated just a little deeper than needed. I didn't care what the book said about seating depth. My loads were light, so I had plenty of room for error (more pressure).

Since you are new to this:

1. Make a dummy load with the bullet as long as possible. When it chambers reliably, set your seating die to 0.010" less than that (this will ensure all of your ammo will feed even if the die gets dirty such as in lead bullets or the press has a little play).

2. For curiosity's sake, check to see what your load book says for COAL for that bullet, if you can find it. I would expect a 180 40 cal bullet to be roughly 1.120"-1.140", off the top of my head. Compare that to your other 180 bullet profile COAL.

3. Check to make sure the dummy round feeds in the mag. Make 5 dummy rounds and feed them through the mag and gun by cycling the slide by hand. They should feed right through.

4. Load up a ladder test. Make 20-30 rounds of ammo with the minimum charge listed in the book/s. 2 tenths of a grain is a nice step. If the min data is 3.5 grains, then do 20-30 at 3.5 and then 20-30 at 3.7 and more at 3.9. If the top load is 4.5, then I would only ladder test to 4.1 on the first outing. You shouldn't need to load more than half way to the max to get good reliability and accuracy, based on my experience.

5. Go shoot those loads. Load 1 round of the minimum charge. Fire it off and see how the gun feels. Did the slide lock back? Did the bullet exit the barrel? Did the brass eject properly and at a normal distance? Did you hit your target? How was the recoil? Does the primer or brass look abnormal like the pressure is high? Then load a few in the mag, if all went well, and fire them again. Next try the next step up which is 0.2 grains more. Compare the way it works the gun. Shoot single handed or single hand with your weak hand. Did it function the slide? It usually takes more power to cycle the gun when you have a weaker hold. If you find a particular load has odd looking primers or it seems real hot, then don't go any further.

6. If you want to refine your load, do more test loads. If a particular load worked well, then ladder test at .1 grain increments above and below that point and include that point as well. This will give you three loads. You might want 50+ of each. Run some drills or shoot some paper as you normally would. See if the point of impact or accuracy is different for each. See which has a better feel in the gun.

I may use a few hundred bullets to test out a profile and weight, before I pick one load. Once I find a load that makes me happy, I will turn it out by the hundreds at a time and I will by multiple thousands of that bullet at a time. If you only plan to buy a small quantity of a particular bullet, you may not want to test so much, but it sucks to load up a big batch and not be happy with it.

My unprofessional opinion is that you would be ok keeping the same powder charge with a different seating depth based on a quick lookup of load data for your powder, but I would highly recommend at least doing a small ladder test starting from the minimum again. It looks like you are probably dead in the middle of the load range for a jacketed bullet, but you are working with a copper plated bullet. Data for those is low to mid range jacketed data. For safety and also consistency, don't start out hotter than you may need.

The ladder tests can be a pita and time consuming, especially when you start to shoot some groups and use a chrono, but you really start to learn more about reloading. Surprises are often not a good thing when it comes to firearms. The extra work will give you practice with setting up your press and powder thrower. I can do ladder tests pretty quickly now. Sometimes they are kind of quick just to get a workable plinking load and other times I will work on it over a number of range/reloading trips to fine tune a gun or work out issues. It can be a simple and quick process to load ammo or it can be long and detailed. Sometimes you get what you put into it.

My brother has 400 rounds of 40 cal left to burn up and he will need to fire them slowly and with a squib rod nearby. If he racks out a live round, he will need a squib rod. His alternative is to pull 400 rounds of ammo. The other alternative would have been to make test loads, or at least do a plunk test with his own gun, and then not load so many rounds. My powder thrower had an issue and caused part of the problem, but he failed to check each case as he set the bullet on them. I noticed right away when I loaded my ammo, that the thrower was not right. The rounds that got a full charge are fine for his gun, but some got little or no powder. My brother doesn't much time to reload or shoot. He loads at my house.

You could put a little or a lot (or somewhere in between) of work and time into setting up a new load. You have to decide which way is best for you. Good luck and let us know if you have more questions, after you work up some dummy rounds and figure out just how different the seating depth may or may not be.