How critical is bullet seating depth? 38spl - Updated

[BillyMays]

Hello all, this is my first post and I am new to reloading. (Thanks new CA ammo buying restrictions).

I am loading .38 special. COAL is listed as 1.550". I am using Xtreme plated 158gr RNFP bullets and seating the bullet so the case mouth sits within the cannelure. This puts the COAL at 1.402". I plan to also do some loads using Armscor FMJ 125gr RN bullets. The Armscor bullets do not have a cannelure.

How do I know the proper seating depth for either of these bullets? I am at least somewhat confident with the Xtreme bullets because of the cannelure, but I don't want to seat either too deep and cause an over pressure situation. I did not find any info on minimum COAL from the bullet manufacturer websites. Am I overthinking this?

Thanks for your help all!

RANGE UPDATE AND FINAL CONCLUSIONS POST #12

[Mayor McRifle]

1.550” is the SAAMI maximum OAL for .38 Special. The SAAMI minimum OAL is 1.275”.


https://saami.org/wp-content/uploads...sting-Copy.pdf (See page 47.)

You’re fine at 1.402”. As always, start low with your powder charges and work your way up. Since the cannelure is putting you at 1.402”, I would use 1.40” for the Armscor bullets, too. You might have to adjust your powder charge for the lighter bullet, but you won’t have to adjust your seating die.

[Fjold]

It doesn't make any difference, pistol rounds are self correcting for pressure due to seating depth.. If you seat the bullets shorter it just gives it a bigger jump to the lands so peak pressure is lower. In revolvers the pressure is even lower because of the cylinder to barrel gap.

[BillyMays]

Is it really that simple? Because my intuition is that heavy bullets seated at the max depth would create far less volume in the case than light bullets at the minimum depth.

Thank you for the SAAMI link, that's very helpful and I hadn't thought of it.

[hambam105]

Good luck getting a consistent crimp on a plated pistol bullet.

[rm1911]

Good luck getting a consistent crimp on a plated pistol bullet.

[hambam105]

That's a nega-tory on that one rm1911.

If you want reliable accuracy from your reloads then you need a consistent crimp. Reloading One-Oh-One.

Plated bullets by the way they are manufactured, are an inferior cartridge component when compared to
hardcast or jacketed bullets for pistol shooting proposes.

For those who have been shooting and scoring all their hits at 50 yards using 38 Special ammo
discovered the phenomenon that using plated bullets of any kind of accurate pistol shooting, bite.

[smoothy8500]

If you want reliable accuracy from your reloads then you need a consistent crimp. Reloading One-Oh-One.

Plated bullets by the way they are manufactured, are an inferior cartridge component when compared to
hardcast or jacketed bullets for pistol shooting proposes.

A simple roll crimp would be all that’s needed for 38spl. Kinda like cast.

I concur with hambam105 that plated accuracy is not up to par with a quality lead or jacketed projectile, but I don't think the OP is considering them for NRA Bullseye either. A light roll crimp is possible and will suffice with the plated projectiles in this case.

As to the Armscor jacketed, I believe they have a brass jacket? At least all the 9's and 45's I have used in the past did. A taper crimp would be better since there is no cannelure. You can use a very light roll crimp just to "iron out" the bell on the case mouth to allow proper loading.

[BillyMays]

Good luck getting a consistent crimp on a plated pistol bullet.

I see you have made your opinion on plated bullets known before:

http://www.calguns.net/calgunforum/showthread.php?t=1545270

However, please stick to the topic I asked about in the original post- anything regarding seating depth, case volume, or overall length. Interestingly, in that same thread I think I found a tip that I will try to ease my mind.

What I usually do is compare the length of the bullet used in my loading manual to the bullet I plan on using and make adjustments in my OAL to ensure the internal case volume remains the same. Just make sure you’re using the same weight bullets.

You can find bullet lengths using this database
http://www.shootforum.com/forum/bulletdb.html

So I will try this and report back later.

[JagerDog]

It doesn't make any difference, pistol rounds are self correcting for pressure due to seating depth.. If you seat the bullets shorter it just gives it a bigger jump to the lands so peak pressure is lower. In revolvers the pressure is even lower because of the cylinder to barrel gap.

I'd add that if shooting from a .357 chamber, there's even more "cushion" in both "bullet jump" and what the pistol will handle.

That said, maintaining a consistent case volume consistent with different bullet profiles of the same weight is a good practice.

[hambam105]

BillyMays
"....anything regarding seating depth, case volume, or overall length...."

The below opinion address all 3 or your concerns with seating depth, case volume and overall length. No charge.
You can thank me later. Television State Law Prohibits Television Reloaders from charging for their technical advice.

Without a consistent crimp to hold the bullet firmly in place, your seating depth may change in the cylinders
or in the magazine when the pistol recoils.

An unanticipated & unknown change in COAL can affect case volume. A change in case volume is a
change in case pressure.

As to seating depth, unsatisfactory crimp pressure may move forward enough to induce a feeding malfunction
in a semi auto, i.e. COAL increase, or with a revolver, if the bullet moves forward in one of the chambers it can bind the cylinder.

[BillyMays]

UPDATE

After reading through some manuals and the previously listed bullet database, I found some useful info for Hornady XTP bullets. I found load listings for a variety of XTP bullet lengths from 0.510" to 0.659", yet the COAL recommended for all these loads was 1.450" regardless of the bullet length. This corresponds to an internal volume change of around 15% depending on bullet used. So in short it seems it really doesn't matter much. Pretty consistent with the answers I received here so thank you all for your input.

So I loaded them up and hit the range! Covered in a separate post here:

http://www.calguns.net/calgunforum/showthread.php?t=1549332

The loads all performed well. Regarding what Hambam105 said about unsatisfactory crimp pressure... I really wanted to ignore this comment because of the snarky attitude. However I did keep an open mind and ran a test. I fired five groups of four rounds from a lightweight snub nose revolver (20 shots). I kept a live round in the fifth cylinder to subject it to the recoil from 20 shots. I specifically chose this gun for this test because it is very "snappy". Anyways, I found that all the test rounds did have bullets shake loose! COAL increased by 0.020"-0.030" as the bullet came loose from the case.

I can't say if the loose bullets were my fault for not crimping them properly, or related to the plated bullets. Either way, thanks for the warning and I'll keep an eye out on it. Further testing to follow!

[justMike]

The used set of dies that I acquired has a Taper Crimp die included. Does no one use this type at all? Interested in the experience of users here about taper crimp on 38spl. Thanks.

[smoothy8500]

UPDATE

I kept a live round in the fifth cylinder to subject it to the recoil from 20 shots. Anyways, I found that all the test rounds did have bullets shake loose! COAL increased by 0.020"-0.030" as the bullet came loose from the case.

Honestly, I would venture that a factory load would "move" after 20 rounds of recoil. Using an inertia bullet puller (hammer) to dis-assemble factory rounds sometimes only takes an extra whack or two. Interesting test results though. It could have moved way more under that condition.

[BillyMays]

Honestly, I would venture that a factory load would "move" after 20 rounds of recoil. Using an inertia bullet puller (hammer) to dis-assemble factory rounds sometimes only takes an extra whack or two. Interesting test results though. It could have moved way more under that condition.

Good point thanks, I'll have to try it with factory loads too some time