Chambering issues with USP-C .40

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bottlerocket

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So I went to the range last weekend to try out some reloads I put together. This was my first time so I made a variety of rounds with a variety of powders but left the dies set the same way. I loaded very light since they were Berrys Plates Bullets.

Basically my problem was, I could have the slide open and put the mag in, click the slide release and it would chamber a round just fine. But after anywhere from 1 to 3 shots it would fail to return to battery and a round would be just about halfway up the feedramp into the chamber.

I talked to a few friends, and two of the most common opinions are either the loads are too light and the slide isnt getting enough momentum, or the resizer isnt set right and the brass is too large for the chamber.

Well I took a few (10) survey rounds from each of my reload batches and every one of them would fall with only gravity helping them, into the chamber with the barrel out of the weapon. Does this rule out the brass sizing? I also checked all of the dimensions to the specs of the round as well as to some factory ammo and everything is within .002"

Is this just a light load problem and I need to step it up a few tenths of a grain?
 
You could always try a little higher charge. Also:

Your OAL might be too long to reliably feed in the magazine.

You might need a little more taper crimp.
 
OAL is actually right on with every factory round I tested within .002", even the ones that failed to feed. More taper crimp? How would that help? Just help it up the feed ramp a little more?
 
Looks like you just need to increase the powder charge.

For semi-auto rounds, you should apply enough taper crimp so the finished rounds drop in the chamber freely and at the most .020" + diameter of the bullet. So for .401" diameter Berry's plated bullet, I use less than .421" taper crimp that will freely drop in the chamber with a "clink".

1. Once you determined the max OAL that will freely drop in the chamber of your barrel without hitting the rifling and

2. Determined the ideal OAL (for Berry's TCFP, I use 1.125" OAL) that will feed/chamber reliably from the magazine when the slide is manually released by incrementally decreasing the OAL (say by .005"),

3. Then next conduct a full work up from start charge of load data with .1-.2 gr increase in powder charge to identify the load that will reliably cycle the slide and produce accurate shot groups.

Like you, I also load 10 rounds of each incremental powder charge from start charge and look at accuracy trends of shot groups. Most powder/bullet work ups will produce increasing accuracy as you approach the max load but not always. Some powder/bullet combination will produce comparable or plateau of accuracy soon above the start charge.

Typically, I look for powder charges that will reliably cycle the slide and extract/eject the spent cases while producing acceptable accuracy. For me, acceptable accuracy from most semi-autos is 1" average shot groups at 7 yards, 2" at 10 yards and 3" at 15 yards.
 
I loaded very light...
Click to expand...
Bingo.

40's tend to deliberately be high-pressure rounds, so your stock recoil springs are designed to accommodate the resulting slide recoil. Since everything else you tell us says your "loading" is OK (cartridge drops into chamber w/ req'd "plunk" sound; first round goes home out of the magazine when the slide catch is released, etc, etc), it's probably just your "load" that needs to increased to mid pressure standards so that the slide move full cycle.

Now you can do that, or you can also get a lighter spring out of Wolffe Springs
http://www.gunsprings.com/
(Cheap.)

I have four different springs for my 45/1911, ranging from 16# (standard) down to 9#
It makes shooter light/target loads fun.
 
I'll try to work up some hotter loads for my USP. Unfortunately Wolff Springs only makes replacements for the full size, not the compact USP. Either way, I need to work on the charge some, so time to hit the press :)
 
It's hard to say without some info.

What where your loads and dimensions. What bullet/weight, powder, weight etc??

My USPC has never even hiccuped.
 
All measurements are averaged
OAL: 1.125"
Diameter: 0.421"
Bullet dia: 0.400"
Case length: 0.839"

Powder used for...:
Berry Brass Plated
-6.9gr IMR800X
-5.4gr Alliant Bullseye
170gr Lead SWC
-4.7gr 231
 
I going through a similar issue with the Berry's 155's. Ive emailed them and they are supposed to be getting me some load data, I'll let you know when they do.
 
I could have the slide open and put the mag in, click the slide release and it would chamber a round just fine. But after anywhere from 1 to 3 shots it would fail to return to battery and a round would be just about halfway up the feedramp into the chamber.
Click to expand...
I had this happen on older Glock magazines with weak springs. It would feed most of the rounds, but would jam on last 1-3 rounds. Replacement of spring fixed the problem.

When you say the first 1-3 shots fed, are you starting with a full magazine? Can you put 1 to 3 rounds in the magazine only and see if they feed/chamber?

Just to rule out if your mag spring is not pushing up on the mag follower enough. It may feed the first few rounds but the spring tension may decrease on the subsequent rounds. As the case rim clears the mag lips, spring tension on the mag follower pushes up on the case rim to line up with the chamber. If the spring tension is not enough, it will hang with nose of the round on the ramp/chamber.
 
So I tried a little more powder (about 5% more) and slightly longer and still had the issue occasionally. When it did happen I ejected the round and set it aside. Every time I took the gun apart and tried to drop the round in the barrel, it fell in flawlessly. It seems the problem is coming from when it tries to push the round up the feed ramp. Could this be a crimping issue?
 
Most likely that the slide is going back far enough to extract/eject but not enough delay to reliably grab the next round. Add mo' powder!
 
I had similar issues with my Beretta PX4 Storm in .40. I was using Titegroup and worked my loads into the mid range and still had issues feeding issues, the rounds ejected but didn't fly far, the slide would come back but not fully close.

I switched to a slower burning powder, HS-6, and have not had the issues even with lighter loads.

I just noticed your powders Bullseye is similar to Titegroup and 800X is similar to HS-6 in burn rates, so this my not work for you. Have you notice any better performance with 800X than Bullseye? I also played with the crimp and OAL to try and get my Beretta to feed better, powder did it for me.
 
Feeding Problem-Extractor-Rim Diameter

It seems the problem is coming from when it tries to push the round up the feed ramp.
Click to expand...
The rim has to slide under the extractor as it slides up the bolt face. If extractor is to tight, little clearence, case head movement is slowed causing a jam. Another problem can be rim diameter not fitting the bolt face correctly. Measure the rim of rounds that do not feed. There can be high spots on damaged rims. Happens with a tight bolt face. 45acp rims can get larger in diameter from many hot loads. Then rims will not fit the bolt face as the have become oval shaped. BoltFace.jpg
 
@Stormin.40

I refuse to use IMR800X in anything anymore unless I am using a powder trickler and loading each one by hand. I have a Square Deal B so the 800X doesn't meter very well. I was getting as much as a -/+1gr variation in my loads so that scares me. I really regret buying the powder to be honest. The first loads were so light that even if it went +1gr it wouldnt matter, but loading a little hotter where I am now, the 800X could easily go over max.

@243winxb

Yea I'm familiar with how it works. It seemed that the extractor was grabbing it fine, but I'll check to make sure its not having issues as well. Thanks for the input!
 
I thought maybe the slower powder would help, but that was my experience and every gun is different. I talked to the LGS about my Beretta and they said that it has stiff springs, as mentioned before the .40 is a high pressure round, so light reloads are going to struggle.

I vote go with more powder, bullseye is a highly recommended powder for many calibers so you should find a sweet spot with a little more tinkering.
 
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