.358" cast bullets for accuracy?

[DanM]

Greetings....The bore of my byf41 slugs to .357-.358". I want to try loading some 125gr, .358" cast RN pills (38 Special) in hopes of improved accuracy.
I assume that you guys have 'been there, done that', so any suggestions would be appreciated....DanM

[lugerholsterrepair]

Dan, Even though your bore may be .358 this does not necessarily make your chamber large enough to accommodate the expanded case mouth. This could result in the casing pressing hard against the chamber wall and causing the bullet to stick in the chamber. Huge pressures could result and your pistol could become a grenade.

If this is something you are determined to do, I would suggest you plug the chamber and get an accurate idea of the exact demensions of the chamber area as well as the mouth of the bore. There are many members out there that put my knowledge of reloading to shame. I hope they chime in and give their opinions. Jerry Burney

[DanM]

Thanks for your reply, but I have to disagree. That fishing weight went down the entire length of the bore, and was swedged down to the exact diameter of the bore at its tightest point. If the chamber was tighter, then the slug would have been squeezed down to match. There is just no doubt about the process. Also, in my experience, the most shooting wear will be at the chamber end of the bore, with less twoard the muzzle end. There is not a safety issue here, I just figured someone had already been down this road, and was wondering about their results. Thanks....DanM

[lugerholsterrepair]

Dan,

"If the chamber was tighter, then the slug would have been squeezed down to match. There is just no doubt about the process."

From your discription I have a doubt about the process even if you don't!


Have you considered the thickness of the brass cartridge casing in the chamber? Pushing a slug down the bore tells you nothing about the diameter of the chamber. The bore will be much smaller than the chamber because the chamber must accomodate the brass casing while the bore does not.
Try this...Load up a dummy round with the bullet diameter you desire and see if it will chamber , cycle and extract. If it does not stick in the chamber and the bolt goes fully forward it is possible you would be safe. I suspect that when you load this up there will be a considerable bulge in the case mouth. This could also lead to head spacing problems. The 9MM Luger is a tapered cartridge and ruining this taper could affect headspace.
I could be totally off base here but I know this much, I still have two eyes and all my fingers. Jerry Burney

[pipeman45]

A chamber cast is the best way to settle this. The supplys and instructions you need for this can be had at any of the better gun supply stores or internet outfits.

[DanM]

Before I got my Schmidt-Rubin K31, I would have said that a tight chamber in an old military weapon was pretty much non-existant, but that rifle has proved me wrong. I have to be very precise with the OAL on my 7.5 Swiss loads because the chamber was designed for the gently tapered, VLD bullet used in their ball ammo. A very advanced design that seats much further out than is possible with US made match bullets. So, you do have a valid point. Considering the amount of wear in the bore (.002-.003"), I just assumed that the chamber throat would be equally loose. You have to admit that a tight chamber on a 60+ year old military self loader would be highly unusual. To be certain, I made a test round, and it does chamber easily and fully. It drops in just as far as my regular ammo, so there is no problem. I hope to test fire some of these loads tomorrow, and will let you know how they do....DanM

[DanM]

Well, I tested the first batch of 125gr., .358" RN slugs today, and the results were less than spectacular. I made up a soft load with 6.3grs. of Blue Dot for an average velocity of 1003fps. My Mecgar mag just won't keep up with my usual, 1120fps 125 gr. loads that work well in my BHP. The 1.160" soft loads did cycle pretty well, but grouped poorly, 4-5" groups were the best I could do, which is similar to what I have been getting with Winchester 115gr. Wal-mart ammo at 25 yards. Groups were 6" high, but that should improve when the new mag springs arrive, allowing me to shoot faster loads. I still think that slugging the bore, and loading cast bullets to fit, is the key to best accuracy from an old firearm. Many, if not most, of the shooter Lugers out there are likely to have bores worn .002-.003" over standard, and could potentially benefit from this practice. Well, I still have 450 of these bullets to play with, and will be trying other powders as time permits. When I finally cook up a winner I will post the results.

[pipeman45]

Do you know how hard the bullets you cast are?

[Karl]

Dan,

I am not a reloader, however, 4"- 5" groups at 25' are not satisfactory for a Luger and suggest to me that ammunition is not the primary reason for such poor accuracy with your gun. I am no longer an especially good marksman due to failing eyesight, but I can shoot a group within about 2" at 25' using crappy Walmart ammo. I suggest that you explore other reasons for poor accuracy before advancing to experiments with fancy hand loads. Best of luck. KFS

[DanM]

The range was 25 yards. Bullets were ordered from Tru-Cast, and are quite hard. I don't have a hardness tester, but they compare favorably with other premimum bullets I have used. I would guess 18Bhn or better. I cast my own bullets for many years, but eventually I could not justify the time involved. Especially since a couple of suppliers started selling at local shows. These guys sell good bullets for $14-16/500, so I decided to get out of the bullet casting hobby. BTW, I never found any relationship between hardness and accuracy in pistol bullets. When properly sized, bullets cast from plain wheel weights, with a Bhn of only 12-13, are as accurate as any. I do prefer a harder bullet in 9mm, at least 15Bhn. In low pressure calibers, like .45acp, plain wheel weight slugs work fine. There are some experts, like Veral Smith of LBT, who recommend plain wheel weight bullets for everything.

[Sieger]

Hi Dan:

Your Luger's groove is in factory spec. at .357 to .358, per the original DWM drawings.

I tried this same little project, about one year ago, with .356, .357 and .358 cast lead bullets.

As the diameters of my test bullets got bigger, groups got tighter!!! At .3565, the action of my byf 41 closed totally (first time, every time) and I got really fantastic groups (7 or 8 touching at 25 yards!!!!). These were cast moly coated bullets.

At .357, groups continued to improve, but reliability got "iffy", as the outside of the case was just out enough to "catch" on the inside of the forward chamber.

Well, how do we solve this little problem (how to keep the outsides of the necks within spec)? That's simple, I purchased two custom neck reamers and ream the inside of the necks the few thousands necessary to clear.

Call Forrester and have them make some up for you. Order exact diameters .356 and .357. This will give you a .001 grip on your lead bullets and should do the trick.

Regarding your accuracy, your loads are not well matched to the Luger.

You will need to concentrate on your powder selection, your OAL and, perhaps, the design of the bullets you are using.

I'll be happy to give you some advice here, as I have been handloading for the Luger since 1978.

Sieger

[unspellable]

Be aware that the Parabellum chamber nominal dimensions are sized to the cartridge nominal dimensions but the barrel nominal dimensions are over sized. There is a risk here of having a cartridge over sized in neck diameter making too tight a fit in the chamber neck area. This WILL drive pressures up! If you disassemble the pistol, the loaded cartridge should fall all the way into the chamber of its own weight and then fall out of its own weight. Any tighter is treading on thin ice.

This neck clearance thing is an often over looked point but I run into the problem with my 400-360 Nitro and with my 454 Casull. In the 400-360 the original brass had a very thin neck and I have to ream the necks on my brass. (They weren't thinking of reloading.) In the case of the 454 Casull the nominal chamber dimensions are very tight and I run out of room with a cast bullet that is slightly over sized compared to a jacketed bullet.

[DanM]

I am glad to hear from someone who has tried this little experiment with good results. I really enjoy shooting older weapons, and always try to match the bullet diameter to the bore diameter for best accuracy. Perhaps the fine construction of the Po8 makes this process unnecessary, but I feel better knowing the exact bore diameter of a vintage weapon, and tailoring my loads to fit. I was very interested to hear that a bore diameter of .357-8" is normal with these pistols. You guys are right of course, and with a new untried bullet I always drop a round in the chamber to make sure it fits. If it sticks out further than a factory round, then it is either too long, or too fat. That is not a problem with the bullets I am using.

I did have some success with one load. The .357 Rainer 125gr flat point copper plated bullet shot very well for me with Winchester Super Field powder. I managed a nice group with four touching and one about an inch out, at 25yds. The load chronoed at 1055fps, and 'felt snappy', which we like. This bulllet is intended for the .357 Sig, but works well in this Po8 at an OAL of 1.125". Any longer and they started binding in the magazine.

BTW, I received the new mag springs and bases from GT, and they are very nice indeed. I have converted one Mecgar mag, and it is working great. I hope to find another at the Greensboro show, and will convert it also. Thanks GT!

[Sieger]

Hi:

Your OAL sounds a bit short to me. I'd have to see one of your bullets to determine this.

If you would P.M. me your phone number, I can give you a lot of tips on how to make a Luger shoot accurately, and above all, reliablely.

Sieger

[DanM]

Update:

Since my initial post, I have made some changes to my P08. The main change was the addition of a new recoil spring from Gun Parts Corp. The cost was $6.00, and function is greatly improved. The new spring was indeed longer and stronger than what was in it. With this new spring, function is near perfect with my unmodified Mecgar mag, and Winchester white box, or my Ranier .357" flat point load. Function is also good with my period mag, although it usually fails to lock the toggle open on the last round. The Mecgar mag that I modified with the GT parts now only works well with hot loads, so I am not using it much. I have no complaints with accuracy. The Ranier load hits at exact point of aim at 25 feet, making ragged, one hole groups, at that distance. At 25 yards, they also group well, but about 8" high. I am also having fun hittting my 50 yard plates, just aim at the base, and they ding every time!
I also had to change the grips. Unfortunatly, the right hand factory grip broke. The thin strip of wood that rides against the front strap, came loose, allowing the right grip to rotate forward during use. Since this one is a byf41, I added a set of aftermarket black plastic brips, also from GPC, (cost $25). They required some work for a flush fit, but look right, and feel great.
So, I am now able to enjoy the Luger experience with an accurate, and good functioning byf41. Thanks to all for the helpful input....DanM

[DanM]

I must revise my statement about my GT modified Meggar mag. I tried it again this past Sat., and it worked perfectly with my 125gr., .357" Ranier load which chronos at 1055fps. I usually load 125s to about 1150fps, so this load is mild for me. I am glad to find a mild load that runs well in my P08.

[Rod WMG]

I don't know anything about Raniers except what little I've read. Aren't those plated soft lead? If so, that may be why they work well for you, giving good obturation in your bore.

At any rate I'm happy for your success.

[DanM]

Yes, the Ranier plated bullets are quite soft. Swaged soft lead core with a thick copper plating. Also, they are the correct size for the bore, .357". IMHO, the tighter fit in the bore makes this mild load build a little more pressure, and allows for better function.