COL Changing Upon Chambering

[dgo]

Reloading 38 Super with 124 Gr JHPs with Lee seater die and "factory crimp" dies on a turret press. In checking COL before and after chambering one round via the magazine and slide, I noticed that I was losing 0.010" to 0.020" probably due to the HP dragging on chamber. I had to dial down the "factory crimp" to almost a roll crimp like I would use on a revolver reload to get the COL to remain the same before and after racking a cartridge. This is more crimp than I usually apply due for an automatic cartridge that headspaces on the case mouth. I have reloaded JHPs in other calibers (45ACP, 9mm Luger, 9mm Largo, etc.) with what I would consider a "normal" factory crimp and velocities per Chrony were exactly as expected; this is the first time I have measured COL after racking the cartridge. Any advice would be appreciated.

[Bullitt2075]

Any round that is fed in a semi-auto will lose COAL every time it hits the feed ramp. It is a violent event. That's why its said not to keep racking the same rounds because of this issue.

Could you crimp a round so hard that it doesn't move, yes but those rounds will most likely be inaccurate.

[DirtyRod]

Originally Posted by Bullitt2075

Any round that is fed in a semi-auto will lose COAL every time it hits the feed ramp.

Not sure I buy that. Sure racking it over time it will eventually shorten but .01-.02 each time!! With proper tention and crimp it shouldn't even be noticable after one chambering. I've chambered a few factory rounds 10 times and barely got .002 on one of them which could have been just me. I've chambered my .45 and 9mm reloads 3-4 times with no change in AOL. I push the tip of the bullet into my bench pretty hard to check the tension and every once in a while I will loose .001-.002.

If it's loosing .01 or more each time the round is chambered I would look at the sizing process and the bullets. The crimp on a straight walled case should be pretty minimal. All I do is remove the belling from the sizing die.

[gringosalsero]

DR,

Correct me if I am wrong, but I thought semi-auto bullets should be held by case mouth tension, not crimping.

Gringo

[moxie]

With proper neck tension a round shouldn't lose OAL until after perhaps very many chamberings. Some factory loads are more prone than others. The crimp has little or no effect.
I suggest you try leaving the Lee Factory Crimp Die out for a while and concentrate on getting the expansion step just right with minimum belling, following by seating/crimping with just a light taper crimp. Measure the OD of the crimp area (case mouth) and check it's .378-.381". See if this procedure helps. If it doesn't, it likely means your expander plug is a bit big.
As DirtyRod mentions, pushing the completed round agaist the bench firmly is another way to check if the bullet is being held in tightly, again really a measure of adequate neck (case mouth) tension.

[gringosalsero]

Originally Posted by moxie

With proper neck tension a round shouldn't lose OAL until after perhaps very many chamberings. Some factory loads are more prone than others. The crimp has little or no effect.
I suggest you try leaving the Lee Factory Crimp Die out for a while and concentrate on getting the expansion step just right with minimum belling, following by seating/crimping with just a light taper crimp. Measure the OD of the crimp area (case mouth) and check it's .468-.470". See if this procedure helps. If it doesn't, it likely means your expander plug is a bit big.
As DirtyRod mentions, pushing the completed round agaist the bench firmly is another way to check if the bullet is being held in tightly, again really a measure of adequate neck (case mouth) tension.

OP is loading 38 Super, whereas quoted crimp is for .45 auto

[moxie]

Correct! Focusing on .45.

Correct crimp OD for .38 Super is .378-.381".

[Nick A]

Sometimes my rounds lose a little length hitting the feed ramp,
but only a little bit. And sometimes none at all.



But...

Make verify that it's the feed ramp doing that.
If your cartridge is loaded too long,
the bullet may set back when it hits
the end of the chamber.
If you confirm that this is not the problem,
then check your case tension on the bullet.
Ignore crimp, that only removes the bell.

[gringosalsero]

Originally Posted by Nick A

If you confirm that this is not the problem,
then check your case tension on the bullet.

Are you saying check this w/o crimp?

[DirtyRod]

Originally Posted by gringosalsero

DR,

Correct me if I am wrong, but I thought semi-auto bullets should be held by case mouth tension, not crimping.

Gringo

Correct. I thought that's what I was saying. Straight walled cases are held by tension not crimping. All I do is remove the flare in line with what Nick stated above. When I pull my plated bullets, there is only the faintest sign of crimping on some of the bullets. On most of them you can't even tell it's been loaded.

[Nick A]

Right, your crimp should be so soft it makes NO difference on bullet tension.



For a semiauto straight-wall pistol, you crimp only to remove the bell.


They should never have named it 'crimp' because it isn't a crimp at all.

They should call it 'removing the bell' because that's what it is.

[cololab]

Possibly it has been mentioned above and I didn't see it, but every now and then you can run across a situation wherein the sizing die itself does not take the case down sufficiently to create the proper amount of tension to hold the bullet in place. I had this happen with an RCBS carbide sizing die and it wouldn't hold a properly sized bullet even when I eliminated the belling step. I switched to a Dillon sizing die and the problem disappeared.

[dgo]

Thanks VERY MUCH for the advice guys. "Removing the belling" is an apt description of what I typically do for straight wall semi-auto cartridges. When I use a kinetic puller to fix a mistake, you can hardly tell the bullet has been loaded. Not so with these; puckered jacket = too tight.

I did make it to the range today and these shot a good 150 fps slower than expected and there were no issues visually with the cases. The pistol (RIA in 38 Super) had a few FTF by jamming...hard...horizontally underneath the barrel ramp. This impact is probably what is making me lose so much COL. So issue has devolved from reloading nuance into me deciding to whether to tackle a "fluff and buff" with Dremel and buffing wheel and paste, or taking it to a gunsmith. It eats FMJs like candy, but is not happy with the JHPs

[bruce381]

""I had this happen with an RCBS carbide sizing die and it wouldn't hold a properly sized bullet even when I eliminated the belling step. I switched to a Dillon sizing die and the problem disappeared.""

I had exactly same problem dillion sizer solved it

[richpetrone]

If your reloads are being set back during cycling, this may lead to serious changes of increased pressure, and should be avoided.

A tighter resizing die may be needed, or check the brass as well. Perhaps some of the brass has thinner walls than others?

Your RIA may be experiencing bullet nosediving when the mag is fully loaded, which causes the bullet nose to dip, and some JHP profiles will often take a near 90 degree hit into the feed ramp and may jam on the first few rounds of the mag. Sometimes, this may be caused by a mag that sits low in the frame. If the fully loaded mag is inserted in the frame until it "clicks" then drops a few thousandths, you might feel some vertical up and down play in the mag. You can check to see if the feeding is improved during your next range visit by supporting the mag underneath with your weak hand, and test fire the weapon so the mag sits higher in the frame. If this helps, you may be able to raise the mags with an over sized mag catch from EGW. They have an oversized ledge that will raise the mag up to .020" higher in the frame. If the mag sits too high, you want to make check that the slide will still clear the mag. You can always reduce the mag ledge height if you have the tools.

[gringosalsero]

Originally Posted by DirtyRod

Correct. I thought that's what I was saying. Straight walled cases are held by tension not crimping. All I do is remove the flare in line with what Nick stated above. When I pull my plated bullets, there is only the faintest sign of crimping on some of the bullets. On most of them you can't even tell it's been loaded.

Would 9mm be considered "straight walled", even tho they are slightly tapered?

[Mike Boufford]

Originally Posted by cololab

Possibly it has been mentioned above and I didn't see it, but every now and then you can run across a situation wherein the sizing die itself does not take the case down sufficiently to create the proper amount of tension to hold the bullet in place. I had this happen with an RCBS carbide sizing die and it wouldn't hold a properly sized bullet even when I eliminated the belling step. I switched to a Dillon sizing die and the problem disappeared.

I'm definitely wondering if this is happening as well. I have no issues with my RCBS .45 sizing die. THe Berry's Bullets 230 gr plated are seating just fine and staying right where they were put. The 9mm on the other hand is experiencing set back even with minimal belling. The 9mm bullet being seated is the Hornady XTP we got as a rebate on the LNL I recently purchased will push back when pressed flat against a table, and also set back upon loading into the chamber. This is very strange to me, but I am going to go back and recheck the bell once again, but this time switch to plated bullets to see if the bullet makes the difference.

[richpetrone]

Once in a while you find the resizing die is proper, yet the expander die that flairs the case mouth may be too large in diameter, and inadvertently reduces the amount of case neck tension. Various reloading presses use different methods to expand the case to allow the seating of the bullet, but this should be checked as well. Dillon powder measures expand and bell the case during the upward ram stroke on the powder measure. They use what is called a powder funnel die, and these are designed for specific calibers. An out of spec. or an incorrect powder funnel die will cause bullet set back. For example, using a dillon powder funnel die for a .38special/.357 will open the case to roughly .356". A .38 super case should be resized to an inside diameter just under .355" or less.

[dickttx]

I started reloading 38 Super two or three months ago using the Lee 4die set. I had some of the same problems.
When measuring OAL turning the roller of the calipers would push the bullet deeper.

Cause #1: I was using 9mm 115 and 125 gn FMJ bullets at .355.
Cause #2: The expander in the powder/flare die was too large.

I took a couple of different approaches:

1. I changed to MBC lead TCFP bullets @ .356, which they show for the 38 Super
2. I replaced the expander in my Super with the one in my 9mm
3. For FMJ's, after sizing in the Super die, I "neck sized" the cases for about 1/4" in the 9mm die and used the 9mm expander.

I started with new Starline cases and had no problems with the FMJ bullets on the initial loading. When I loaded them after firing was when I had the problem.

I have found 38 Super to be an interesting adventure.

[DirtyRod]

Originally Posted by gringosalsero

Would 9mm be considered "straight walled", even tho they are slightly tapered?

Yes. Load them like any other straight walled case.

[Rifter]

Originally Posted by Mike Boufford

I'm definitely wondering if this is happening as well. I have no issues with my RCBS .45 sizing die. THe Berry's Bullets 230 gr plated are seating just fine and staying right where they were put. The 9mm on the other hand is experiencing set back even with minimal belling. The 9mm bullet being seated is the Hornady XTP we got as a rebate on the LNL I recently purchased will push back when pressed flat against a table, and also set back upon loading into the chamber. This is very strange to me, but I am going to go back and recheck the bell once again, but this time switch to plated bullets to see if the bullet makes the difference.

Check the headstamp on the cases where you can push the bullet in. Remington often has case walls a bit thinner than other brands. In .45, I've found Starline brass to work very well as far as wall thickness goes.

Years ago, I also had a carbide RCBS sizer that didn't squeeze 'em down quite as much as I liked. I solved the problem at the time by turning down the expander plug by several thou so that all it did was bell the case mouth. I was using military brass back then, however, which seemed heavier to me.

One way that you can eliminate the problem is by using a case canneluring tool to put a cannelure on the case body under the point where the base of the bullet sits. That puts a mechanical barrier in place that prevents bullet setback. That was the fix the military used on their ammo for a long time.

[gunnut606]

Originally Posted by dgo

It eats FMJs like candy, but is not happy with the JHPs

If you really want to shoot JHP, then try some Rem. JHP because they have the profile of FMJ bullets, and they seem to shoot very well in all the guns that I have shot thru.
.

[dgo]

This is great advice guys.

Yes, the RIA is nosediving with mag nearly full and this is apparently a common issue with them. This is my first RIA and it is a great pistol for the $$$. JMB 1911s are technically not supposed to eat JHPs anyway... JHP on 45 ACP at 850 fps is of marginal benefit, but JHP on 38 cal boolit going 1,250 fps is a Good Thing. Per a thread in the RIA section, their outstanding customer service will send you a replacement mag well release and 18.5lb recoil spring for free. Will definitely try this before Dremel!

The 124 gr JHPs are indeed Remingtons and this is the first feeding issue that I have had with them. Bought them in bulk because they were cheap and have ended up really liking them. These Remington bullets work flawlessly in my Sig 226, BHP and CZ75 in 9mm Luger and in my modest collection of Spanish Steel in 9x23 Largo (the REAL 9mm).

I have a Lee 4 die setup in 9mm Luger, but backed out to Largo depths. Will do the belling for 38 Super loads on this setup and see how that works. Brass is Rem nickel plated and is likely thinner than Starline. Starline is my favorite brass.