Same grain, different bullet type

[joerockt]

I've been loading Rainier 155 grain 40s&w bullets for some time now. I just recently bought Precision Bullets 155 grain 40s&w. The difference is the Rainier bullets are plated, while the Precision's are coated in a dry-lube.

So my question is, even though the bullet weights are the same, does the different coating on the Precisions change my recipe at all? I'm going right out of the Accurate Arms load guide. I'm using AA#5 @ 7.1 grains with an OAL of 1.130.

[saands]

Assuming that both bullets are also the same length, then I would say that if your load is 95% of their max load or less, then you probably don't need to worry about it. If it is a max load, then you will want to back off and work it up ...

IF, on the other hand, the Precision bullets are longer than the Ranier and you are seating them to the same COAL, then the new ones will be seated deeper and your case volume will be lower ... this causes the pressures to be higher ... especially in short straight-walled pistols cases. If this is the case, then you should either seat them to the same depth (but this might affect feeding) or reduce the load a little and work back up. If I were doing it, I'd load up the work-ed up loads and do a "risk build" of a range session's worth of the final load ... expecting it all to be fine, but being willing to pull the bullets if I turned out to be wrong

That's my $.02 worth ...

Saands

[joerockt]

Ah, good point. I have to measure one of the Rainiers and one of the Precisions. If the Precisions are longer or shorter, then I would just compensate for that difference and set my seating die accordingly, correct?

[saands]

Well ... it depends

As long as the adjustment doesn't make the OAL longer than the max allowable, then that should work fine. My guess is that the change will be tiny ... if you were going from a hollow base or hollow point to a solid bullet, then you might find a significant difference, but if they are roughly the same shape, then you should just be able to adjust your seating depth accordingly.

Be safe,

Saands

[joerockt]

I measured. Its about .017 longer then the Rainiers. The minimum OAL for this load is 1.125. So Im looking at an OAL of at least 1.142. Think this might cause a feeding issue? I guess I need to keep in mind alos that I'm only using .2 grains above the minimum load, so I probably dont need to be too concerned with this different in size, should I?

Oh and is there a way to find out what the max allowable OAL is for a specific pistol? Specifically, I would need the data for my XD40.

[Sevens]

Max allowable COAL is not a measurement given for pistols or by manufacturers. It's set by SAAMI and is exclusive to the caliber. Certainly, any particular firearm may allow a longer than SAAMI max COAL, but you wouldn't try and make ammo specifically for it. Even if your pistol would chamber it, it may not reliably feed it, or it may not reliably run through the magazine.

If you did specifically make longer than SAAMI max COAL, it could be argued logically that you are no longer making ammo in that caliber. Instead of making .40S&W ammo, you'd now be producing a proprietary round that we could call ".40 JoeRockt". Hey, that might be a big seller!

But it makes sense. By having dead-set standards, it avoids compatability issues and dangerous situations. Of course, handloaders will always be likely to specifically tailor their ammo to certain needs, but in a combat pistol round, you've got nothing whatsoever to gain by trying to exceed SAAMI specs for COAL.

Rifle rounds, now that's a totally different scenario.

[joerockt]

Ok. According to my Modern Reloading manual, the standard .40S&W cartridge OAL is 1.135.

So, In trying to keep PSI the same as with my older bullets, and using the bullet depth of 1.142 I would be exceeding the standard by .007 (hehe). So would that be pushing things, or does it all depend on the tolerance of the pistol? 7 thousands of an inch doesn't sound like it would be a big deal?

[Sevens]

At 0.2 grains above the starting load, no, you aren't doing anything scary.

Just keep your eyes open for signs of pressure. While it's incredibly important to do things properly and be smart about it, there's a lot of safety margin built in. By that, what I mean is-- if you've gone wacko and way, way overloaded a round, your brass and your pistol will let you know what you've done (hopefully) long before you do any damage to the pistol itself, or to yourself.

Crushing primers, piercing primers, bright extractor spots on case heads (or ripped off case heads!) and brass that's cracking or deforming, these are all signs that you've done bad things. 0.2 grains and/or .007 less internal capacity aren't at all going to take you that far down the road.

But you are seating bullets out further -- not deeper, correct? If that's the case, you only need to worry about feeding and magazine issues.

A cheap, quick and easy way to see if you've made rounds that will chamber is to field strip your pistol and drop a factory round in to the chamber. Pull it out, and drop in one of your newly made reloads. From the ass-end, it should be seating and feeling and chambering the same. If it does, you are golden.

[saands]

If you are just 0.2 gr above the STARTING load, then I would just seat them to the same COAL and call it a day. According to an interior ballistics model I have (QuickLoad) the loads are likely to produce 1900 psi more (since you are at the start load, this shouldn't be an issue at all) and give you 20fps more velocity ... you won't notice the difference.

Good choice on your XD40. It has a fully supported chamber, so it doesn't have that little issue with being sensitive to cases that have had Glock "smilies" (look those up on the search) put on them. Without a fully supported chamber, I would be cautious using range pick up brass for that reason ... with it, I don't have any concerns at all.

Have at it!

Saands

[joerockt]

Thanks guys, I appreciate the help...