.357 Magnum size question

[Schwing]

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]

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!

 

[AABEN]

Clean it after shooting 38 Sp before shooting 357.

 

[TfflHndn]

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.

 

[RPegram]

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.

 

[Walkalong]

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?

 

[brickeyee]

Get a chamber brush.
Scrub thoroughly.

 

[RPegram]

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.