cerrosafe castings do i really need it done?

[edadmartin]

id like opinions on cerrosafe casting. I get along with my Smith pretty well and understand also hes in business,needs to make a profit etc. he said my newly purchased 1992 marlin micro groove 336 in 30-30 should be both barrel and chamber cast to determine what size bullet to cast and col and head space.he mentioned that anytime you buy an older rifle its worthwhile to get castings done.to verify what you have, its not cheap. and the rifle will be R&R, and cast.plus all necessary action parts will be cleaned and polished barrel cleaned out too.
now that im writing this it seems worthwhile but at 160 dollars im cringing a bit,your suggestions??

[William Yanda]

Have you shot it yet?

[Wayne Smith]

Cerrosafe is available from Brownells and from Rotometals, both sponsors here. It is not hard to use, it melts at a low temperature. You can do it yourself if you have a kitchen stove or a propane torch and something to melt it in. It can be reused once you get measurements off it. It shrinks at a predictable rate and then expands at a predictable rate. Keep a record of when you cast it and the size related to your chamber is easily figured. Once you cast knock it out as soon as it hardens. It is literally easy. No point in paying someone else to do something this easy. Save money for what you can't do.

[shredder]

It is so easy to do your own chamber and throat cast. For a 336 lever gun in 30-30 I wonder why. Load up some lee 160 RN under 10 grains of Red Dot or something similar with a proven record in 30-30 and you should be good. I use the chamber and throat cast when things do not go as planned and I need some answers. I have never done it right from the start, though some will chime in to state the necessity of doing that. YMMV.

For 160 bucks , go get a good mould for that rifle and a can or 2 of powder to boot!!

[Yodogsandman]

Cerrosafe shrinks. You can just do a pound slug of your throat as described in the stickies. The pure lead slug won't shrink and will answer all of the same questions. Easier and much less expensive, too.

[runfiverun]

find the sticky on doing a pound slug [goodsteel started it]
this will tell you everything you need to know about your rifles throat.
and the measurements don't change over time.

[Tom Myers]

find the sticky on doing a pound slug [goodsteel started it]
this will tell you everything you need to know about your rifles throat.
and the measurements don't change over time.

This is a link to GoodSteel's post. It is in two parts so be sure to scroll on down a couple of posts to the second one.

http://castboolits.gunloads.com/showthread.php?218414-FYI-This-is-how-I-do-a-pound-cast

Below is a link to the Precision Bullet Design ~ Ultimate help file for a slightly different method of a Chamber Impact Impression.

Chamber Impact Impression

This following details a method of making your own hardwood slug mold for impact impressions.

Making a hardwood slug mold for impact impressions


Another Link to some details of measuring Cerrosafe Chamber Casts.

Cerrosafe Chamber Casting

Hope this helps.

[44man]

I have used the stuff many times and never got as accurate as pure lead. No matter how I timed it, numbers were always under size.

[matrixcs]

I have used the Rotometals chamber casting alloy with good results. There is a necessity to be paying attention to the time when measuring and casting..
According to Rotometals
Melts between 158 and 190 degrees Fahrenheit

Should be melted in a clean iron ladle without direct flame on the product.

The chamber being cast should be cleaned thoroughly and a thin coat of oil or graphite applied.

Reusable

Contraction expansion factor versus time, measured in inch per inch compared to cold mold dimensions. Test Bar x 10
2 minutes - .0004"
6 minutes - .0007"
30 minutes - .0009"
1 hour + .0000"
2 hours + .0016"
5 hours + .0018"
7 hours + .0019"
10 hours + .0019"
24 hours + .0022"
96 hours + .0025"
200 hours + .0025"
500 hours + .0025"

[Bent Ramrod]

Edadmartin,

Your own signature line answers your question. If the rifle is in sound condition (and your gunsmith can tell you that for a lot less than 160 scoots) you should be able to get all the data you need to have with the making of a dummy cartridge and twenty reloads using any flatnose .30 caliber cast boolit in the 150-170gr range and 0.311" diameter.

If you were buying a bench rest rifle, a wildcat or an antique of unknown caliber and provenance, maybe those operations would be necessary. But in your case, they aren't.

I have a bunch of "older" rifles and have done chamber casts on maybe three of the weirdest calibers and slugged the bores of about ten more. Unless I can't figure out the chambering to order loading dies, or encounter some accuracy problem in shooting, these measurements come under the heading of "too much information."

[MostlyLeverGuns]

For $160 you can pleasantly experiment with a lot of bullets! Tap a .310 or .315 round ball through the barrel if you want the diameter. Spend some of that $160 on a decent dial caliper. See how that .311 cast bullet chambers. BENT RAMROD has it right. I have ' bunch of old/older rifles', mostly 30 cal, I start with a .310 flat nose 160-180 grain gas check with 18-20 grains Rldr 7 or 4198 and go from there. Works for .30-30, .300 Savage, .303 Savage, .308 - Marlin 336's and Savage 99's. Maybe .309 or .311 might be better. 16 grains or 21 grains better than 17grains. 4227 or 2015 better than 4198? Only SHOOTING can answer these questions. There is a lot/tremendous amount of information on the .30-30 and reloading techniques for it. RELOADING and SHOOTING provide the answers, not chamber casts or bore measuring. Observe your results, on target and at the loading bench. You can enjoy that $160, OR your gunsmith can.

[edadmartin]

I agree that casting seems not necessary for this rifle after all.I did nt know it shrunk and accurite measurements depends on how long you wait after popping the casting, alot of variables having never done it my self.still seems not definitive enough to spend 160 bucks on.ill shoot my commercial rounds to see how she shoots, then slug the barrell and see what size bullet is needed,from everything ive read it will slug larger than .309, so ill have to be on the look out for a bigger mold than i have .
ill borrow a friends col guage,i think it a hornady, in fact ill watch him first .
great input from everyone,thats why i like the forum.

[Tom Myers]

I have used the stuff many times and never got as accurate as pure lead. No matter how I timed it, numbers were always under size.

44man,

I believe that the correction factor that is supplied with the Cerrosafe alloy is actually taken from an original test performed on a rectangular bar of fairly large size.
While correct for that particular size of bar, It sure does not work for smaller sized bullets.

After collecting many measurement values of different chamber casts taken at varying time intervals, I came up with a formula that seems to work quite well when applied to the data that I have collected.

Just out of curiosity, if you have an old Cerrosafe casting lying around, try this method and see what the results are.

I will use one of my several years old Cerrosafe castings of a Marlin 94 25-20 chamber that I had relined to provide an example.

Measure a diameter on the casting - I'll use the chamber neck as it is clean and free of the dings caused by quite a few years or being banged around.

My micrometer shows a measurement of 0.2788".

My records show that an impact impression made of the chamber resulted in a neck measurement of 0.2776"


25-20 Cerrosafe chamber neck measurement of 0.2788"





This is how to manually do the calculations.

Multiply the Cerrosafe measurement value by the Hours-Since-Cast
0.2788 x 1000 = 278.8
Multiply this value by 177.62
278,8 x 177.62 = 49520.456 = (value # 1)

Multiply the Cerrosafe measurement value by the Hours-Since-Cast
0.2788 x 1000 = 278.8
Multiply this value by 178.39
278.8 x 178.39 = 49735.132
Subtract 1 from this value
49735.132 - 1 = 49734.132 = (value # 2)

Now, divide value #1 by Value #2 to get the correction factor.

49520.456 / 49734.132 = 0.9957036 = the correction factor

Finally, multiply the Cerrosafe measured value times the correction factor.
0.2788 x 0.9957036 = 0.2776 = the actual measured value of the chamber neck from an impact impression of the chamber.


I measured the groove diameter on the Cerrosafe casting and this is the result of the calculations. (Not perfect but "Close enough for Government Work")

[edadmartin]

Love the comment " reloading and shooting provide the answers"
we live in an age of wikii and you tube.

We cant make a move until weve searched the net for truth,you cant start anything until you spend your dollars on unnecessary stuff,like a right of passage.
i continually have to remind my self to use the brain God gave me ,and do it my self. Let common sense and logic prevail, not the wallet. Confiring with a band of brothers in arms also never hurts.

[Char-Gar]

OK, truth telling time! Paying a gunsmith to do a cast is a waste of money and doing a pound slug is a waste of time.

The 30-30 Marlin MG barrels tend to run large in the grooves and lands and have a short or non-existant throat. Many cast bullet designs won't work well in these barrels. Fortunately there are some that will. Get a copy of Ranch Dog 165 grain gas check bullets, which was designed for this rifle. Lube and size it .311 and go shooting.

311407 Mod. as sold by NOE will also do well in your rifle.

That is all there is to this. No sense in making it difficult and esoteric. Many have gone on this road before and know the way.

[sghart3578]

OK, truth telling time! Paying a gunsmith to do a cast is a waste of money and doing a pound slug is a waste of time.

The 30-30 Marlin MG barrels tend to run large in the grooves and lands and have a short or non-existant throat. Many cast bullet designs won't work well in these barrels. Fortunately there are some that will. Get a copy of Ranch Dog 165 grain gas check bullets, which was designed for this rifle. Lube and size it .311 and go shooting.

311407 Mod. as sold by NOE will also do well in your rifle.

That is all there is to this. No sense in making it difficult and esoteric. Many have gone on this road before and know the way.

This plus 1.


SH

[44man]

Agree with Char-Gar too. My Marlin likes a .311" boolit and a .301 bore ride.
RD will work.
Good work from Tom too, I have timed the stuff to the second to get false readings.

[edctexas]

Cerosafe castings work well but... IF you screw up putting the liquid metal in the chamber you pay heck trying to get it out. In a semi-auto pistol, where the barrel comes out it is easy. Still if you wait too long for it to cool, it may get stuck in there.

I have tried several ways. There is a Sticky about doing a "pound cast". This is a great way for a non sophisticated shooter to measure the chamber, throat, and bore near the chamber. In most rifles, there can be a compromise between throat, freebore (if any), and bore dimensions. The pound case is a safe way to get all of that info. I would do a pound cast and spend your $ on lead, primers, and powder.

Ed C

[Hang Fire]

To each their own, but I much prefer the impact method using dead soft lead. Are you aware that Cerrosafe castings are only accurate within a certain timeframe after casting and will continue to change dimensions over time?

https://www.google.com/#q=impact+met...ber+dimensions

id like opinions on cerrosafe casting. I get along with my Smith pretty well and understand also hes in business,needs to make a profit etc. he said my newly purchased 1992 marlin micro groove 336 in 30-30 should be both barrel and chamber cast to determine what size bullet to cast and col and head space.he mentioned that anytime you buy an older rifle its worthwhile to get castings done.to verify what you have, its not cheap. and the rifle will be R&R, and cast.plus all necessary action parts will be cleaned and polished barrel cleaned out too.
now that im writing this it seems worthwhile but at 160 dollars im cringing a bit,your suggestions??

[Outpost75]

Most .30-30 Marlins I have measured were sloppy in the chamber neck and in the barrel groove diameter.

If you have bullet sizing dies of various diameters, the easiest way to check is to assemble DUMMY rounds with FL sized case and sized bullets of various diameters, and try to chamber these in your rifle. I would bet money that your Marlin will probaby accept dummy rounds assembled with .311" diameter cast bullets without felt resistance, and that you will feel hard closure of the lever, resistance to action locking, and that the dummy upon extraction will show rubbing on a tight neck with .312" diameter bullets.

If I were to guess out of the blue the proper diameter for any Marlin .30-30 it would be .311". In the remote possibility that a dummy with .311 bullet chambers hard and shows rubbing on the neck, then you know to use a .310". In the equally remote possibility that it gobbles up a dummy with .312" bullet, try a .313" and see if you get resistance.

Fit the bullet to the chamber neck and brass wall thickness, NOT to the barrel groove diameter.

Use the largest cast bullet diameter which chambers and extracts in dummy rounds freely with NO resistance.