Rem 380 UMC Bulging


PDA






docsleepy
May 30, 2010, 05:37 PM
Has anyone else seen this?

New Taurus .380 738. >50 Winchester .380 white box through it, no problems at all.

Bought a box of Rem .380 UMC and was very surprised that every round (upon firing) had a bulged case on one side, from the web to a couple of millimeters forward. This did NOT happen with Winchester - all retrieved cases were perfect. The winchester was flat point, the Rem was RN.

The bulging fits perfectly an area of the barrel where the feed ramp connects/enters, which does not seem to be supported. From the shape of the bulge, the case had moved slightly backwards during the event. I have not yet investigated other .380 designs to see if the Taurus is unusual in this respect.

I concluded I would just pull the remaining 30 or so bullets and reload the cases with a weaker charge. Upon attempting to pull them with a kinetic (whackamole) puller -- I cannot pull them at all. I have whacked harder than I ever have before, and they do NOT come out. They are IN there hard. I *was* successful in pulling a Win.380 (to measure how much space was left between powder charge and base of bullet).

Measuring the COAL suggests also that for my particular barrel, the bullet may be nearly touching the lands -- it is about .020 farther "out" than I had planned to seat my Berry's RN bullets. This, too, could be increasing the peak pressure, in addition to the really firm taper crimp.

Seems I am getting higher pressure with the RemUMC than I did with the Win -- both commercial ammmunition. I don't think I'll fire any more of the Rem in that particular gun. I've used Rem UMC 9mm and .223 with complete satisfaction before; this is my first .380.

Has anyone seen this before?

If you enjoyed reading about "Rem 380 UMC Bulging" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
KodiakBeer
May 30, 2010, 07:48 PM
Does the Taurus have a section of unsupported chamber like Glocks?

Robert101
May 30, 2010, 11:42 PM
If you are suspecting that the bullet is not completely champering then this could be a serious issue. Is the slide going completely into battery? It should and must completely close.

Might I suggest that you remove the barrel and place a round in the champer. Confirm that the bullet completely seats as it should. I'm one of the few that reload .380 for my Browning DBA. I have not had a problem with OAL or to short of a barrel throat.

Cracked brass in a factory loading is unusual and the reason should be explored more thoroughly.

AS a last thought, with the barrel out of the gun, try chambering varios types of ammo and see if they fully seat or chamber.

Full Metal Jacket
May 31, 2010, 12:21 AM
UMC is the worst ammo i have used. after about 15 years of using it, on and off, i will no longer buy it (not even if it's on sale anymore lol)

i've gotten entire boxes where every bullet was sunk down into the shells, and light powder charges where the bullet barely made it out of the barrel.

docsleepy
May 31, 2010, 07:33 AM
Thanks guys, for the great info.
1. There appears to me to be a small section at the junction of the feed ramp and barrel where, just like the Glocks, the case is unsupported.
2. I'll check the UMC seating into the barrel later....good point.
3. I dont have any proof tht it isn't going INTO battery;

what I suspect is that the case, during backwards recoil movement, was still experiencing high pressures (due to the tight crimp) and therefore as the case disengaged from the barrel in the course of recoil, it bulged. This is a locked breech design, and my understanding of that is that the bolt/case/barrel move backwards as a unit for a bit during recoil, and THEN begin to separate. However, if the crimp is making it harder to get that bullet free, then the timing of all this migght be different than a case that had released its bullet earlier.

4. Yes, I do think RP brass might be softer and this might be part of it; aggain I NEVER saw this in any Winchester brass.
5. I don't have another 380 so I can't test this.
6. The brass did NOT split; it just bulged....but that was very concerning to me. The only other brass that I've seen bulged was some .223 I picked up at the range in huge quantity that I think must have come from a semiauto .223---every shell was bulged....and I thinik that was RP brass also. I've never had any bulging in my Taurus 99 (9mmm).

I'll pull the barrel out later and compare to the barrel of the Taurus 99 and see how the support of the case compares, and also check seating of the UMC ammo. thanks for the info!

Steve 48
May 31, 2010, 11:00 AM
Never had a problem with UMC brass with the TCP. In fact I shot 100 of the in a full size target in the head area without a malfuntion or bulged brass.

bannockburn
May 31, 2010, 11:20 AM
docsleepy

Is the UMC ammo new Remington Green Box ammo?

docsleepy
May 31, 2010, 12:26 PM
Thanks for the additional info.
1. Yes, the TCP738 appears to have a section of the case that is unsupported, based on my comparison of the view of a .380 shell in the TCP barrel, compared to a 9mm shell in a Taurus PT99. In the 99, only the barest part of the web way in the back is unsupported. In the TCP738, there are a couple more millimeters that look unsupported. There is a clear difference to my eyes.

2. The Remington that bulged was Remington 380 UMC Automatic 95 grain MC L380AP. It was newly purchased.

3. When I place a fired (range pickup) PMC or Win case in the barrel, the base of the case is exactly flush, to 0.5 thousandths below the "tang", the furthest rearward extension of the barrel. I had also some fired Rem UMC (range pickup, not my gun) and they were a little tighter and I didn't get them into the barrel (they appeared to have expanded more than the PMC or WIN, but that could be the firearm chamber in which they were fired).

However, when I place a new Rem 380 UMC from this box into the chamber, the base of the case is .010 to .014 ABOVE the tang, suggesting what I was concerned about--that the bullet is hitting the lands, and the shell is being headspaced on the BULLET, not the case mouth. In my own planning for a RN Berry's Bullet, I planned to seat the bullet somewhat deeper (more than .020 deeeper) than this Rem UMC is, just to be certain the case headspaced on the mouth, not the bullet. I made those calculations prior to purchasing the Remington; I did them by just a lot of measuring and planning, which is what I always do prior to starting up using a new caliber or bullet.


So the remington seems
1) tighter crimped than the Win ammo (unscientific comparison that I can successfully remove Win380 bullets with a kinetic tool and I cannot remove the bullet from the Rem) -- which would lead to somewhat higher pressures
2) somewhat significantly unsupported by the TCP design (which seems to favor guaranteed success in getting the case up the feed ramp, rather than guaranteed support around the entire circumference)--the lack of support favors bulging (but had no problems with the Win380 ammo)
3) headspacing on the bullet, not the case (meaning even more of the case is unsupported)

I don't have any velocity data and since I can't disassemble the Rem I can't tell you how many grains of powder are in there, and of course I can't tell what KIND of powder. I remember when I disassembled the Win, I was impressed with the somewhat high number of grains, and I concluded it might be a powder similar to 700X, and at max loading based on my Sierra manual, but this is pure conjecture since I don't know what powder it is!

dwhite
May 31, 2010, 01:16 PM
Take those rounds you could not pull the bullets from and try seating the bullet a little deeper to break any sealant that may be holding them. Then get out the kinetic bullet puller and give them another try.

All the Best,
D. White

Full Metal Jacket
May 31, 2010, 03:29 PM
So the remington seems
1) tighter crimped than the Win ammo

exactly the opposite. the main issues i have with umc is a weak crimp (or no crimp at all), and the round already sunk in their shells while in the box.

bannockburn
May 31, 2010, 04:05 PM
docsleepy

I compared three .380 rounds that I have; Remington (same as yours), Blazer Brass, and Aquila. All three chamber to the same depth with the case well supported by the chamber. The Remington and Blazer ammo have near identical dimensions, both being 95 gr. FMJ designs. The Aquila is a 90 gr. slightly truncated hollow point.

docsleepy
May 31, 2010, 07:44 PM
bannock: were your measurements in a TCP738? Perhaps they have more than one barrel design!!

Made up test rounds for reloading and found the following:

DISCLAIMER: THESE DATA FROM MY EXPERIENCE ONLY. CONSULT PUBLISHED DATA. DO NOT RELY ON MY EXPERIENCE.

100grain Berry's (plated lead) RN FB. Approximately 80 degrees F.

Win231: COAL 0.937 (chosen to leave .020 gap before lands from ogive)

2.0 grains 481 fps 51 ft lbs: would not cycle action
2.5 grains 600 fps 80 ft lbs: cycled action x 5 (100%) brass fell within 3 feet
2.8 grains 676 fps 101 ft lbs: cycled action x 5 (100%) brass long way away
(no bulging on RP brass)
3.0 grains 735 fps 120 ftlbs : cycled action 100%, brass a long way away, and barely perceptible bulging noted on RP brass [way way less than noted with commmercially prepared RP brass--this is a weaker loading]

for comparison:
WINCHESTER white box 95 grain 858 fps, 155 ftlbs This is fairly "mid range" in my Sierra book, which shows loadings all the way to 1000 fps, 211 ft lbs.

The max for 95 grain FMJ using Win231 in the Sierra book is 3.4 grains, while the Hodgdon site suggests 3.1 grains; hence I stopped at 3.0 grains.

The RP brass seems a bit weaker, and my particular TCP738 may have a barrel with a bit less support. I don't know if other Taurus' have the same barrel or not. I'm actually quite happy with this 380 handgun; it cycles perfectly over a very wide range of loadings -- all the way from 600 fps (and possibly lower) to 860 fps. Recoil at the lower ranges was very, very light, and quite tolerable even with the commercial loadings. For my purposes (target and concealment), this is filling the bill perfectly. I think I'll just stick with Winchester brass!

docsleepy
May 31, 2010, 07:49 PM
I found a photo of the chamber of a TCP738 on gunblast.com

http://www.gunblast.com/images/Taurus-PT738/DSC09589.JPG

and my chamber looks very similar. I think you can see what I think is a somewhat unsupported segment above the feed ramp.

As several have noted, Rem UMC ammo appears to have considerable variability! It is possible that I just got a box with a lot tighter crimp than many others....

If you enjoyed reading about "Rem 380 UMC Bulging" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!