Proper cast bullet fit?

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jphendren

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Hello,

I am wondering how tight a cast bullet should fit the cylinder throats of a revolver? I have a Registered Magnum and a Colt Python that I am trying to find the right bullet for. I pushed a commercial cast SWC through both of them and the RM takes a little pressure to get it started, but then slides through easily. The Python takes a bit more force to get the bullet into the throat and gets stuck. Measuring the bullets after they've been through the throats, the registered magnum bullet measures .358, and the python bullet measures .3575. What size should my bullet ultimately be? .359 for the RM, and .358 for the Python?

On another note, I am looking for a .357 mold for these. I am considering the Lyman 358429 Keith, or the RCBS 38-150 K. Also like the H&G #51, but they are very hard to find.

Thanks,

Jared
 
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I'd slug the barrel of that Colt and see if the throats match the barrel. Undersized throats cause problems.
I use .358 lead in my S&W.


How do they shoot with commercial .358 lead? Nice to be able to use same loads unless your are forced to customize for each.
 
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I just checked my S&W model 29 .44 magnum and my Ruger .357 Vaquero. The jacketed bullets will drop through the cylinder and throat and the cast bullets have to be pushed through the throat. Bottom line the throat should match your cast bullet diameter. When the throat is smaller than cast bullet diameter is when your problems start.

The links below cover throat diameter, fire lapping and tapered bore for cast bullets.

A Contemporary Look At Barrel Leading and Related Sixgun Issues
A Contemporary Look At Barrel Leading and Related Sixgun Issues

Accurizing the Ruger Single Action Revolver
by Roy Seifert
Accurizing the Ruger Single Action Revolver

Below click on the image to get more info, correct diameter, reaming, fire lapping etc.
revolver cylinder throat - Google Search
 
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I think you should be OK with .358 for both.
Good luck in your search for a H&G mould.They are of excellent quality and the demand for them is high since they are not made anymore(from what I've heard,Magma has bought the tooling).RCBS makes a very good quality product.I have 4 or 5 of their moulds and they cast very accurate bullets.
Maybe you should also consider Saeco which in my experience are the best of the non custom mould makers with RCBS following closely.
Qc
 
If you're experimentally inclined, and it sounds like you are, try a couple of different sizes in each. There are exceptions to everything, including the rule-of-thumb cylinder throat bullet fit. Slightly oversize (a tight fit when pushing through) or a slightly loose fit may work fine.

Factors like hardness, pressure of the load, and, of course bullet diameter and the amount of obturation ("slugging up" or bullet base swelling upon firing) all may affect accuracy. Only way to know for sure is to try. Varied powder charges and maybe several powders will tell you even more.

Slug the bore if you wish, but I wouldn't be too concerned about bore diameter unless a gun shoots terribly after you've tried everything else. If so, then is the time to slug the bore. Colt's often run real tight in the bores, but I have two Pythons that do well with .358" bullets, just like my S&Ws.
 
Forgot to mention the H&G #51. This is my favorite .38 and .357 Mag. bullet. I've always found it to shoot better than the #358429, though the #358439 (HP version) does almost as well as the #51.

Custom mould makers can probably duplicate the #51. This was the original .357 Magnum bullet as developed by gunwriter/ experimenter Phil Sharpe in the '30s.
 
I like the Lyman 358156 gas check and the 358477 plain base for my Smiths. Never had a leading problem with them. Just sized and lubed some yesterday.

Have a blessed day,

Leon
 
Thanks for the replies,

I haven't shot either of these guns in several years, but my old load was 11.5gr of 2400, a wspm primer, and a commercial 158gr bullet. That load shot okay but leaded the barrel. Those bullets are bevel based and rock hard. I now cast my own bullets for the 44 Magnum and 45 Colt. I use 1:20 alloy, I think it's about BHN 10-11. That alloy seems to work well at revolver pressures.

I would like to try it in the .357 caliber as well, just need to find a mold. I am considering the Lyman 358429, but that bullet is too long for a N-frame or python cylinder I have read. I am also concerned that the heavier weight may not shoot to point of aim on my revolvers. Both of my revolvers shoot to point of aim with 158 grain bullets, I don't want to adjust the registered magnum sights for fear of damaging them. From the pictures that I have seen, the RCBS 38-150 resembles the H&G #51.

Jared
 
The #358429 was an Elmer Keith design for the .38 Special. It will work okay in the .357, but the bullet must be deeply seated and crimped over the shoulder (if that makes sense). I can't remember point-of-impact difference vs. the same for the #51, but I doubt there would be much difference as the #358429 is only about 8-10 grains heavier than the #51.
 
I am considering the Lyman 358429, but that bullet is too long for a N-frame or python cylinder I have read.
Click to expand...

Lyman 358429 and it's H&G counterpart #43 were designed by Elmer Keith and will not damage your gun. The are used in short cylinder guns such as the S&W M27's and M28's by seating them deep and crimping over the top of the top driving band. Perhaps the most popular cast bullet for the .357 magnum is Lyman 358156 (H&G #135) which is a 155 grain gas checked SWC designed by Phil Sharpe. It can be used in either .357 cases or .38 Special cases. It has 2 crimp groove and 1 grease groove. The middle crimp groove can hold lube if the bullet is used in magnum cases. Used in .38 Special cases, it can be seated shallow and crimped in the middle groove allowing near magnum level and 38/44HD loads to be built safely in the shorter case. Seated normally and crimped in the top crimp groove in magnum cases, the loaded rounds fit the short cylinder Smith's. It was Skeeter Skelton's favorite bullet for the .357 magnum. He used them largely in .38 Special cases. At the time, the .38 Special S&W revolvers dominated the LE market and once fired 38 brass was readily available as a reloading component; .357 magnum cases not so much.

Bruce
 
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The #358156 is an excellent bullet, perhaps equal to the #51 in accuracy. Gas check designs usually shoot best with the gas check attached, but I suppose they could be used without.

A gas check doesn't take the place of good bullet fit and proper alloy. If all's not right, a gas checked bullet will lead like a mismatched plainbase bullet.
 
The rcbs 150 is one of my favorites. Size it 0.358", with 20-1 alloy, I would be fine to 1200fps or so with a good lube.
Fwiw, you do not need a mag primer for 2400, accuracy will likely be better.
 
I ended up buying a used RCBS 38-150. I'm going to give that a try and see how it goes.

I was using a mag primer because Hornady listed them in their load manual for 2400.

Jared
 
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I seldom used a magnum primer with #2400 in .357 Magnum loads, but about ten years ago did a comparison of all domestic small pistol primers, CCI, Federal, Remington, and Winchester, standard and magnum.

With #2400 powder and the H&G #51, I fired five, five-shot bench-rested groups at 25 yards with each primer using a 6" Colt Python. In every instance but one, there wasn't much difference in accuracy, but the magnum primers had a slight advantage.

Winchester was the exception, with the magnum primer proving inferior to the standard version. I also shot the largest group average with the Winchester magnum primer, 3.1". Federal Magnum was the best, averaging under 2".

While interesting to me, this evaluation probably proved little. It included only one handgun, a selected assortment of primers that might not be representative of what's currently available, and other component variables. All loads were fired by a not-so-skilled handgunner. It also didn't persuade me to switch from the CCI 500 standard primer that I had been using for a long time in all .357 loads.

Only if I was interested in long-range handgun accuracy would I find a need to evaluate primers again. I'm pretty sure it would make a difference there.
 
An undersize bullet will always lead the bore, regardless of being hard, and a harder bullet might even make leading worse. Rifles and semi-auto pistols might have use for harder bullets than revolvers.

What is needed is a bullet of 12-15 Brinnell, a good bullet lubricant, and the bullet sized to fit the throats of the revolver's chambers. As long as the throats are equal to, or larger than, barrel groove diameter you should not have any leading. If the throats are smaller than groove diameter you will have problems with leading, no matter what else you do, until the throats are brought to barrel grove diameter or up to .002 larger.

Once you have established that you have a proper fit between the cylinder throats and barrel grove diameter, forget the barrel diameter; size the bullets to the throats. This can be a very tight fit and still be OK. The barrel will do the final sizing. There will be no measureable increase in pressure.
 
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My '72 snub nose Python is as follows:

Chamber throats - .3585"

Bore Lands: .348"
Bore Grooves: .354"

I shoot .358" coated SWC from MBC without issue. That gun is very accurate too.

I would suspect most Pythons are very close to the same measurements. My '75 Python 6" is about the same, and that thing shoots like a laser.
 
I size all my .38/.357 for my Smiths to .358, and use a Hornady crimping gas check on the 358156. Always worked well for me.

Have a blessed day,

Leon
 
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