.357 Magnum size question


July 7, 2013, 06:57 AM
I purchased a Ruger GP100 .357 Magnum a few months ago and reload for it along with a couple of .38 Spc (S&W and Rossi) and a 9MM Ruger SR9. I am running into an issue with the .357 rounds dropping into the cylinder. Some fit tight and after shooting, actually come out easier. These same rounds that are tight in the GP100, will drop right into either of the .38's with no problem. They don't go all the way down, but will fall down to the point the .38 round would sit. I would say 90% of the .357 reloads will drop into the GP100 without effort, 8% to 9% will go in the cylinder with a push and 1 or 2 out of a hundred will just not go. I use 158 gr LSWC from MBC. I also use mixed head stamp once fired brass. The rounds which fit tight in the GP100 will have resistance to going in when the brass starts entering the cylinder and then all the way. I have cleaned the cylinder very well so there is no carbon ring from shooting .38 rounds in the .357. The cylinder is mirror clean all the way down to where it reduces in size. I have taken the gun to a local gun smith and he told me the Ruger has tighter tolerances than either of the .38's, so he believes the issue lies in my rounds I loaded. The issue is not related to just nickel plated or a particular head stamp. I seat and crimp in two different steps with the same die. I use Lee dies and it is the carbide 3 die set. I start off with a very slight crimp, just enough to basically straighten the brass out and remove all the flare. The rounds that won't go all the way into the cylinder, I can crimp again and squeeze a little more, and then they will go into the cylinder with some effort. Strangely enough, they will eject easier than when put in. I resize, deprime and prime with the first die, all in one step, then flare and drop powder on the second step, all done with a Lee single stage press. I am using .357 dies. I originally thought it could be related to using .38 dies, so I purchased the .357 with same results. After shooting 200 rounds, there is little to no leading in the barrel.

Is it possible that some of the brass is just so much thicker that when used for cast lead it causes this issue? Has anyone else run into this and if you did, what did you do to take care of it?

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July 7, 2013, 07:32 AM
It may not be your problem but something to look at.

25 years or so ago, I had a carbide die that did not size the 357 Magnum/38 Special case quite far enough down to the base of the case. It left a little "bulge" for lack of a better term that after several firing/reloading cycles would get to the point the case would not chamber.

Generally, this was not an issue with low power 38 Special loads but was with mid to full charge 357 Magnum loads.

At that time, a steel resizing die that I had would iron out the bulge. Frankly, I have not loaded or shot much 357 Magnum lately so I do not know if the new carbide sizer I bought has the same issue.

Anyway, take a magic marker or Sharpie and blacken the side of a few cases that do not chamber. Insert them in the chamber and the marker will get scraped off where you have a problem. You may have to cycle the cartridge through a couple times and if loaded cartridges do this in a safe manner.

Hope this helps.

July 7, 2013, 07:44 AM
Make sure your resizing die is set correctly. Needs to be screwed down to shellplate. I use Lee pistol dies, they work great. I doubt your factory crimp die has anything to do with your problem. Is your brass name brand stuff? I had to chuck a bunch of CBC brass in the garbage, They'd wrinkle the cases in the center upon seating.

July 7, 2013, 09:39 AM
mixed head stamp once fired brass. Case trim length must be close/the same when crimping. Long brass, when crimped, will get a bulge if the die was adjusted with a short case.

July 7, 2013, 11:19 AM
Wow! I have the same exact problem with the same exact gun. 148gr DEWC/3.4 gr HP-38/WSP
I thought it was getting some buildup from the 38 would sit of in the cylinder but it is clean.
The same rounds are fine in my 686. I ended up using a heavier crimp which helped.
I finished off that box of bullets and got some 125gr Berrys FP which have no problem at all.

July 7, 2013, 12:25 PM
I will try the sharpie trick and see what happens. Right now I'm leaning toward the thickness issue to be in the area of the case where the bullet sits. I say this because the rounds are hard to push in the chamber all the way from the end of the brass until fully seated in the chamber.

The resizing die is correctly seated to the best of my knowledge. I install the die with the press rod all the way up and turn the die until it just makes contact with the shell plate and then snug up the locking nut. I cheaped out and did not buy any of the quick change bushings, so I have to set each die every time I change steps.

The only brass I've noticed that makes a difference is Hornandy in relation to case length. There is enough difference in those I have to separate and load separately from other headstamps. Hornandy is considerably shorter brass, enough my flare die won't do anything to the opening.

Interesting to hear the same problem encountered with the same type gun. The gunsmith I took mine to told me he thought it was a combination of the tight tolerances of the Ruger, slightly larger diameter of cast bullets and a little extra thickness of some brass. Take away any of the three variables, and all is well. Different gun, rounds fall right in, different bullet, round falls in Ruger. I do remember loading some JSP and JHP with no issues of dropping in cylinder. I had forgot about those as that was quite a few months ago.

I have entertained two ideas:
1 - have the chambers in the cylinder reamed out .002". Just that little bit removed would probably make all the difference.
2 - Buy a FCD and use that only on the stubborn ones. My concern with that is reducing the size of the bullet and the issues that come with undersized lead.

July 7, 2013, 12:52 PM
You described setting your sizing die in a way that I think is your problem. If you are "just touching" the shellholder then locking it down, this is probably not far enough. Presses has some slop in them, along with the shell plate. So to get a full sizing, you should follow Lee's instructions.

Screw the die in until it touches the shell plate, then lower the ram and screw in an additional 1/4 turn. This ensures the slop in the holder/press is taken out of the equation.

I would also recommend using your seating die as a seater only then using a factory crimp die.

July 7, 2013, 12:56 PM
Here is a ink that shows what Lee recommends: http://www.youtube.com/watch?v=S0ZCahQp05U

July 7, 2013, 12:59 PM
I second the notion of seating and crimping in separate steps. I think some of your brass is long and bulging the case below the crimp.

July 7, 2013, 01:00 PM
Screw the die in until it touches the shell plate, then lower the ram and screw in an additional 1/4 turn.That is not correct for Lee carbide handgun dies.

(It is correct for Lee bottleneck steel rifle dies.)

If you screw a carbide handgun die down an additional 1/4 turn, you are likely to break or loosen the carbide sizer insert in the die.

Don't do that.

Lee instructions for carbide handgun dies.
Screw the full length sizer in until it touches the shell-holder and
tighten the lock ring finger tight


July 7, 2013, 01:07 PM
Not according to the official Lee video on the Lee website - http://leeprecision.com/single-station-die-adjustment.html

July 7, 2013, 01:15 PM
Not according to the official Lee carbide die instructions.

It has long been known to not adjust carbide dies for hard cam-over shell holder contact as broken carbide rings can result.

They should just touch the shell holder at full ram travel.


July 7, 2013, 01:23 PM
Not according to the official Lee carbide die instructions.

It has long been known to not adjust carbide dies for hard cam-over shell holder contact as broken carbide rings can result.

They should just touch the shell holder at full ram travel.

Conflicting instructions for sure between video and paper instructions. Interesting.

July 7, 2013, 01:40 PM
I would look more towards the crimp or fouled chambers from shooting .38 Spl.

July 7, 2013, 02:20 PM
The instructions that came with my dies say turn the resizing/depriming die down until it contacts the shell holder with the ram all the way up and that is what I have been doing. I have chambered resized/primed brass and they fall right in the cylinder. My problem happens when the cast bullet is seated in the brass.

With a light crimp, most of the reloads will fall into the cylinder with no problem. Those that are difficult, they require a little heavier crimp. Those that won't go at all the first attempt, require a couple of recrimps, and eventually they will go with some pressure. I simply take my thumb and push hard and they will go all the way down. With each recrimp, I tighten the die down a little more.

Last weekend I spent over 2 hours cleaning just the cylinder. I used solvent on a brush wrapped with a patch on a drill. I would do oil patch first, then follow with 3 different patches per hole soaked with Remington 40-X bore cleaner, then an oil patch followed by a dry patch. The inside of all chambers look like a mirror all the way down to where the drop in size is. I did this complete process many times. It took a lot of cleaning patches.

The gunsmith thought the same about shooting .38, but when he looked down the cylinder he remarked how clean it was. He looked after the cleaning, but before any shooting.

July 7, 2013, 02:24 PM
Your sizing die is adjusted correctly and has nothing to do with your problem.

Try this:
Take a couple of the tight rounds and color them completely with a black Magic-Marker.

Then force them to chamber.

Where the black rubs off is what is wrong.

I just have a feeling you are buckling the case with too heavy a roll crimp.
Maybe not enough to easily see, but enough to cause chambering problems.


July 7, 2013, 04:04 PM
make sure your cases are not too long. trim if necessary.


Lost Sheep
July 7, 2013, 04:52 PM
If you still have not identified the problem by any other means (including measuring your brass' diameter and length with calipers), you might want to take the trouble to do this:

With a representative sample of cases and bullets (each brand of cases and type of bullet where the combination is giving you problems, plus one combination that does not give you problems).

After sizing and depriming (re-priming is optional), chamber the cases. Observe how much free play there is and write that down. Measure diameter at the base, middle and mouth of several cases. Also length. Write down the measurements and keep the measurements identifiable with each individual case.

Flare the cases as normal (powder is optional, but if the cases are not primed, do not charge with powder for obvious reasons). Measure the diameter of the cases at the mouth and at the point where the base of the flaring mandrel was and at the middle of the case. Observe any changes in diameter. If the flare permits, chamber the cases. Observe how much free play there is and write that down. Compare with your earlier observations

Try to seat a bullet with your fingers. Will it go?

Seat bullets in the cases as normal, but without applying any crimp whatsoever (flattening out the flare is OK, but just to bring the case mouth into alignment with the rest of the case near the mouth, no more than that).

Measure the diameter of the case at the base, the middle, the base of the bullet and the case mouth. Write them down.

Chamber the cases and write down your observations.

You now have a blow-by-blow detailed record written down of how each bullet/case combination behaves/misbehaves. Plus one control combination of well-behaved bullet/case.

If you did not discover, during the process of loading interrupted by all the chambering and measuring, where the problem is developing, studying the behavior side-by-side of the well-behaved combination and the misbehaving combination should reveal the problem.

If the problem(s) doesn't/don't reveal itself/themselves at this point I will have to think a little harder. Problem with the dies? Misalignment of the press? Shellholder off-center?

Lost Sheep

July 15, 2013, 07:22 AM

Yesterday I spent some type reloading 200 rounds, in two batches of 100 each. I reload with a single stage, so 100 is a nice round number that is easy to keep up with.

I measured the length of all cases prior to reloading and sorted accordingly. The longest were loaded first. This way I knew the longest cases were used to set flaring and seating dies.

After resizing and repriming, all cases dropped in cylinder flawlessly. Turn gun upside down, and all fall out without help. Outside diameter of brass showed very little variance when measured with digital caliper.

Flared slightly, just enough to feel the flare and bullet would sit on brass with no help. Could not push bullet into brass with fingers after flaring. When I did seat the bullet, there was resistance inserting the bullet, not a lot, but you could feel the drag. Prior to seating, I measured diameter of bullets, 158 gr. LSWC from Missouri Bullet Co. and all were extremely close in diameter.

When I crimped, just enough to straighten cases mouths. I had 6 that would not chamber and a few more that would bottom out, but were snug. I crimped a little more and got down to 2 that would not chamber due to bulging cases. Prior to crimping tighter, the difficult rounds all showed a bulge from the neck opening to the base of the bullet with no bulge below bullet. These rounds when inserted in the cylinder showed marks from just below crimp to base of bullet with no contact of brass and cylinder below bullet.

On the next 100 reloads the adjustment I made was with the flare. I flared less. Flare was barely noticeable and bullets would just barely sit on top and some had to be guided into the seating die. I did not get any shaved lead. When I crimped this batch, I went with a medium crimp. I had 5 that would not chamber and only a couple that were snug. Less flare and a medium crimp the first crimping round helped with snug issue, but did not eliminate the non-chamber issue. This time I ended up with 3 that would not chamber even with heavier crimping.

The first batch that would not chamber both had a headstamp that looked to be Russian? 357 magnum was stamped, but had three symbols appearing like Russian letters.

Second batch that would not chamber also had the foreign looking stamp, a WW Super and G.F.L.

When diameter of brass was measured where bullet was seated, the bad ones were .001" to .002" larger. The bulge was consistent from neck to base of bullet. Hopefully a picture will show the foreign stamp. The rounds that would not chamber were not the longest nor shortest, but actually in the middle of the group. When seating with the first batch, one or two would scrape the inside of the seating die when the bullet was being seated. This is the reason I opted for less flare the second batch. The second batch, none scraped the inside of the seating die. On the second batch, I would test brass after flaring to make sure none would make contact inside of die by inserting them by hand in the die.

With all the measuring and chambering, the two loading sessions took around 4 hours. I narrowed down the headstamps to three. All the weird looking stamps were difficult or impossible to chamber, fortunately I have few of these. All the Winchester, Remington, Federal, Blazer and several others all drop in cylinder perfect. Nickel plating made no difference, they worked fine except the WW Super. Length of brass made no difference, all bad ones were mid length. Bullets are extremely consistent in size. No bulges below base of bullet. Bulge is consistent in size from neck opening to base of bullet, in other words, no looking light a light bulb. Less flare and medium crimp helped reduce number of rounds that were tight when loaded in cylinder, but made no noticeable difference in number that just would not chamber fully and had to be discarded. I would crimp a little harder trying to get rounds to seat, until a bulge would develop below the bullet.

I'll try any ideas and let you know the results.

July 15, 2013, 07:23 AM
Trying the pic of weird stamp:

July 15, 2013, 07:28 AM


July 15, 2013, 11:28 AM
RC is correct, according to the instruction in my carbide pistol dies. I actually broke a Lee 9mm carbide sizing ring a few years back because I had too much cam over, or pressure as it were, against the shell holder. And RCBS dies are very specific about this as well in their die instructions. It's OK to make light contact with the shell holder, just not heavy cam over as you would with a standard steel die.

If you are not making contact with the shell holder, you can still bring the die down a bit more until it makes light contact. That may be all you need to solve the issue? I also know a few who actually take a few thous off the shell holder, I'm not one of them.


July 15, 2013, 12:09 PM
I don't believe resizing is the issue. I say this because after resizing, depriming and repriming, the brass will fall into the cylinder and fall out without any help. They completely bottom out with no resistance whatsoever. All brass did this with no difference in headstamps. Thanks to Walkalong, I now know the PRVI brass dropped into the cylinder with no issue at all. I had not tried this earlier, but yesterday I did this test with the brass prior to flaring.

I install the resizing/depriming die with the ram all the way up. I will screw the die down until it just makes contact with the ram and lock the nut down. I keep one hand on the handle to make sure the ram does not drop any at all.

The issue was after seating the bullet. The bulge in the case where the bullet is inside was the tight area with all the marks on it. The bulge was uniform in shape from the neck of brass all the way to the bottom of the bullet. It was a perfect print of the bullet inside. No bulge prior to bullet seating. After flaring, all brass uniform in size from below flare to base. No other marks anywhere on the brass.

July 15, 2013, 12:35 PM
It's also possible you have bullet seating bulges, though these are more common with 180 or 200 grain cast bullets. Inspect your sticking rounds to see if you can notice or feel any slight bulge around the base of the seated round.

July 15, 2013, 01:44 PM
Tight chambers. Have gun smith adjust.

July 15, 2013, 02:00 PM
I have a GP100 and have a similar issue. From what I have read, this is almost universal with the GP100. I still believe it is due to carbon buildup in your cylinder from shooting .38s. Ruger does not leave much wiggle room at all. In some ways, this is not a bad thing since it is great for accuracy. Like some others have mentioned I also shoot a 686 and my GP100 side by side and have never had any issues with the same rounds in the 686.

Right out of the box, I took it to the range, fired about fifty .38s through it and then tried unsuccessfully to seat any .357s. The .357s I was shooting were factory ammo and they still would not seat all of the way. I was convinced that there was a problem with my gun until I did some research about this problem. This was before I even had .357 loading dies so a problem with the ammo didn't even occur to me. After a cleaning, the same ammo had no issues.

I have found that I have to keep the cylinder 100% immaculate to avoid this problem. This means thoroughly cleaning it every time after shooting .38s. Even shooting 6 rounds of .38 is enough to stop mine up. I have never had the issue just shooting .357s. I have also started using an over sized brush to clean out the cylinder and have had much better results since then.

Hondo 60
July 15, 2013, 02:03 PM
I can't say that I've ever seen the OPs issue.
But it sounds to me like it may be an OVER crimping issue.

If you crimp too much it'll ever s slightly buckle the case.
If you can post a pic of the finished rounds, we can better diagnose the problem.

Anyways, welcome to The High Road!

July 15, 2013, 02:21 PM
Clean it after shooting 38 Sp before shooting 357.

July 15, 2013, 03:45 PM
Try M-Pro 7. Comes in a black pump spray bottle. Spray on, leave for a few minutes, carbon, led and copper almost fly off the gun. You'll know it's clean and eliminate carbon or lead fouling as any potential cause.

July 15, 2013, 05:21 PM
Another update after reloading 100 rounds.

First thing was to remove all PRVI, WW Super and G.F.L. headstamps. I left one WW Super in the batch just for giggles. I did not measure lengths as I could not tell length made any difference before.

After resizing, depriming and repriming all brass, all would still fall into the cylinder with no problem.

Next to flaring and dropping powder. I flared just barely and brass would still drop in cylinder, although one or two pieces were a little snug, but all went. A few snug is expected as there is some variance in length of mixed headstamp brass. All brass, just as times before, was once shot range pickup.

Seated bullets. Tested many, but not all. Again, drop into cylinder without much issue.

Onto crimping. Went with a medium crimp. My test WW Super round was in the middle of the batch and when I came across it, tested to see if it would chamber. No, it would not. Crimped and still the same, no chamber, would barely start in cylinder.

After testing, fit test all again. All of them, except the WW Super fit. That one got trashed. I did find another headstamp, S&W that had a little drag going in and would pop right out with a tap of the ejector rod. All other brands dropped in without the slightest drag. Turn the gun upside down and all others fall out without touching the ejector rod.

My conclusion. There are at least three different brands of brass I cannot load LSWC's into: PRVI, G.F.L. and WW Super. I can use S&W, but it will have to pushed down into the chambers and won't just fall in like all the rest. Sometimes the G.F.L. can be crimped a little heavier and work, but most times not. Evidently those three brands have just a hair thicker case walls than the others. No problem with jacketed or plated, but an issue with cast in a GP100. They may work with a smaller diameter cast bullet, but these do so well, I don't really want to spend the money and find out.

If I had not put the one WW Super in the batch, I would have had a 100% success rate, but that one helps me figure out the brass is the issue with my gun, not my reloading.

The previous owner may have shot some .38's, but I have not. The cylinder is spotless inside. I bought a .357 Magnum because well, I like the kick of a magnum. I don't load to max, but I do use a good strong powder.

July 15, 2013, 06:13 PM
Well, it's obviously the crimp causing problems. .357 Mag brass lengths are all over the place, so my guess is that some of the cases are not getting crimped into the cannelure, whether above or below the center of the cannelure where it has some depth cor the case mouth to roll into.

Should look something like this.

Or this.

They don't go all the way down, but will fall down to the point the .38 round would sit.Cleaned the cylinder yet?

July 15, 2013, 06:27 PM
Get a chamber brush.
Scrub thoroughly.

July 15, 2013, 07:01 PM
In post #15 I described how I cleaned the cylinder. Killed one battery in the drill and had to get the second.

Here is a pic of three of the rounds I loaded today, just randomly picked out of the box.

What I found today is the problem exists before crimping. I had one WW Super headstamp brass that had previously given me issues and that round would not go in the cylinder after seating, but prior to crimping. All other rounds (99) went fully into cylinder after seating and after crimping.

I did see a little difference in the amount of flare today due to differences in length of brass. Since I reload on a single stage press, I get to feel the flare of each piece. The ones that felt a little larger would still go into the cylinder prior to seating or crimping. The 99 out of 100 that fit prior to crimping, still fit after crimping with no change.

The one today that would not go into the cylinder was not seated deeper than the others. The top of the canulure was just visible above the brass.

If the WW Super brass was not included today, I would have had 100% success. The first time since switching to cast.

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