SB1 with cast bullet rifle loads?

[tturner53]

I understand the limitations on using an SB1 frame. I believe it is pressure based. Factory .357s and .44 Magnums come on SB1 frames, which get in the 40,000 cup range at the top end. Any reason a cast bullet rifle load(such as a .308 Win.) that's way under 40,000 cups would be a bad idea? This is assuming a good barrel fit, lockup, and small firing pin hole,(all of which I have now). The importance of controlling the possession of this combo is obvious, wouldn't want it to get shot with full power loads. Some people will ask 'why do it all?'. I just want to know if there's a good reason why not? Is there an issue besides pressure? I'm talking about cb loads in the 20,000 cup range.

[quickdtoo]

Pressure isn't the only factor in breech thrust, the size of the case head, or more specifically, the internal area of the case head plus pressure determines case head thrust,  more commonly referred to as bolt thrust. The larger the case head, the lower the pressure needs to be to be safe.  http://www.riflebarrels.com/articles/custom_actions/bolt_lug_strength.htm

I don't think it's a good idea personally, what if you died unexpectedly and some unknowing new owner ended up with the rifle and loaded it up with factory ammo? 

Tim

[tturner53]

Thanks quick, I appreciate the input. Your point is a good one, I am responsible for whatever happens if someone else got a hold of the incorrect combo. Just mostly thinking outloud, I don't really need to use an SB1 for these loads, I'll have 3 SB2 frames by next Friday, so will keep this one in the what if category, not try it. I tried doing that formula for bolt thrust, lost me completely. I don't know some of the symbols in the formula, but I was real impressed with the chart showing the psi ratings for different Rockwell hardnesses.

[Spanky]

A 44mag has a larger case head and is loaded to 40,000cup. The factory offers it on the frame you have. I wouldn't think shooting a 20,000cup load with a smaller case head would cause any problems. The factory used to sell 30-30, 44mag, 45-70, 357mag/max, 22jet, etc. all on the iron frame also. The 45-70 has a much larger case head and some of the trapdoor level loads are approaching the 20,000cup level you are talking about. Just use some common sense and be safe.



Spanky

[quickdtoo]

The 308 has a .470" case head, the 44mag is .457", rim size is irrelevant. 

Tim

http://stevespages.com/page8d.htm

[Spanky]

Aaaahhhhh... and the 45-70?
I'm just saying use some common sense. All this voodoo nonsense about using the SB1 is just that... nonsense. If they used 'em before then why ain't they any good now. The new SB1's are probably stronger than the old frames.



Spanky

[mechanic]

I haven't tried to Rockwell my SB1, and it wouldn't be a good number anyway, as the cast will still be more brittle than steel.  When time allows however, I may check my SB2.  For comparison, most ball peen hammers of good manufacture, are about 55-59 that I have checked.

I have an anvil that will exceed 60.

I have a cast steel anvil as opposed to my forged steel one, that is plenty hard, but brittle, and especially along the edges will break off chunks suddenly.  Cast steel can be hardened and tempered, but not to the same degree as forged steel.

A cast iron anvil of the type Harbor Freight and some other market, will not sustain blows from a hammer.  It will dent, it will crack, and it will shatter under the right circumstance.

I would expect the SB1 when it fails would likely fail in a major way with lots of pieces going everywhere........

[quickdtoo]

Speculation will get someone hurt, that's pretty foolish IMO since we have no idea what the frame strength of the old frames is compared to an SB1. Common sense would be using an SB2 frame for a 308Win regardless of the load plans.

Tim

[mechanic]

Speculation will get someone hurt, that's pretty foolish IMO since we have no idea what the frame strength of the old frames is compared to an SB1. Common sense would be using an SB2 frame for a 308Win regardless of the load plans.

Tim

+1

[Spanky]

Point taken fella's.
I ain't trying to start another pissin' match.



Spanky

[parson48]

Nothing much to add to the conversation except to say that clearly marking the frames couldn't be a bad idea. I've had guys in a gun shop tell me that a rifle was on SB2 because of barrel markings. I had 'em go get the box, which stated SB1.

[NFG]

There is a whole lot of difference between cast IRON and cast STEEL...Ruger makes cast STEEL receivers...they are as strong or stronger than Rem, Win, Mauser etc. NEF SBI receivers are cast STEEL not cast IRON...but only NEF KNOWS what the composition of the steel is or what level of shear/tension/malleability/ductility/tensile strength etc, the SB1 receiver is designed for.

A whole bunch of people don't know the DIFFERENCE between the two...It's just cast "something" to them.

You also need to remember that ALL METALS are CAST at some point, then extruded, pounded, stomped, hammered, drilled, cut, reheated and so forth, to become some object of desire.

NEF/REM is the sole authority on WHAT caliber goes with what frame...NO ONE KNOWS except NEF if there has been any changes in the steel formula and that information isn't something that gets bandied about.

The bottom line is USE YOUR HEAD...there are always reasons for things.

As far as the "stuff"(no diss or flame intended) about case head size and "Thrust" is concerned you can calculate the thrust with the simple formula for the area of a circle...Pi X Radius squared...then multiply that times the pressure.  The difference between a .470 s and .532 size case head is about 2000 psi at 40KPSI...understand this information and all you need do is reduce the load pressure, if and when the cases start to stick.

What a person does in the way of changing parameters belongs on HIS/HER shoulders, irregardless of anything else.

While there is more "thrust" with a magnum size case head and much less with a .223 size case head you only need be concerned if you go nutz and push the pressure way beyond reason, but after you calculate the numbers you should be surprised and maybe start rethinking some of the "stuff".

FWIW...Dan Lilja has some very interesting information on bolt thrust/shear concerning bolt lugs and Varmint All has some interesting stuff on the same WITH some engineering drawings.

I built 17 FB and 6mm BR a couple years ago that both stick the cases in the chamber similar to Freds 25-06, but the pressure is WAY below anything that could cause the frame to come apart and no where near max pressures for that cartridge.  My BC will also locks sometimes at pressures way below max but will pop out the case without a hitch when I do get it open.  (The 17FB uses a the original NEF 17 HMR barrel and the 6mmBR a section out of the middle of a barrel originally a 6mm-284...maybe I need to rough up the chamber a bit.0

All that information aside....NEF says how the cow ate the turnip about their products so I would follow their recommendations...it does'nt matter WHAT the calculations or anyones conjecture says.

Luck

[quickdtoo]

Now ya got me wondering about the cast vs iron, the SB1 frame has been referred to as ductile in all my correspondence with my Marlin/H&R tech, he never stated whether it was iron or steel, I wasn't aware there was ductile steel tho either, here's one of the replies concerning the prefix change after Remington's acquisition of H&R, he refers to the SB2 as a steel frame, and the SB1 as ductile.

Tim

Effective May, 2008 , the prefix for steel frames is CBA. On ductile frames, the prefix is CAC. I do not know when the prefix will be updated to reflect a new year of mfg.

[petemi]

My 7mm-08 barrel and scope are sitting in a corner pouting cause they don't own a frame or a stock.  I recently acquired a .30-30 barrel that fit perfectly on the 7's frame and stock, so there it stayed.  All my rifle barrels go on SB2 frames........period.  That way, there's no questions, no problems.  To me, sitting around and second guessing on this issue is looking for trouble.  What happens if barrels are changed out and an '06 barrel is put on the SB1 frame and loaded with super hot ammo?  Yeah, we may not do it ourselves, butcha gotta look down the line somewhere.

Pete

[quickdtoo]

I just got an email reply on SB1 frame material, they're ductile iron, not steel.

Tim

[Spanky]

Not really sure where the poster above got the "sb1's are cast steel" info but thanks for setting things straight Tim.



Spanky

[NFG]

I didn't mean to muddy the waters, or stir the pot or confuse....ductility has a specific meaning in engineering-eze.

The point I was trying to make is people have different understandings of terminology...and that point was misunderstood as I didn't make myseft specifically understood.

Many people envision "cast Iron" like in cast iron skillets...whack it hard with a hammer and it will break or shatter..."ductile iron" is a metal that can be hammered, or cast or shaped under pressure, "hammered" into thin sections without shattering, splitting, cracking etc...it has specific engineering parameters determined by the engineers designing specific metal mixture to produce the product parameters they desire...ductility, malleability etc...all words with specific engineering meanings, and mostly outside the understanding of the average person...me included.

This internet is read by so many people it is almost impossible to convey a precise meaning without confusion...that's why I quit posting...I didn't want what I understood to be misconstrued and get someone hurt...it is all too easy to read something into a post that wasn't meant, by someone that didn't quite understand the full meaning or intent of the words.

The other point I was trying to make is NEF decides WHAT to call their product...they are the sole authority...and no matter what ANYONE outsided NEF says, it AIN'T NECESSARILY SO.

If you follow the rules layed down by NEF you shouldn't get hurt...if you go outside those rules YOUR bacon is in the skillet(pun intended).  Sometimes blindly following the rules is the better course of action...and keeping quiet is many times even better...I think I will go back to that course again...just following various threads without commenting.

My desire to pass on what I've learned overrides my better judgement many times.

Luck

[NFG]

FWIW...and for those who want a "better" answer GOTO

http://www.ductile.org/

All the information reguarding what "Ductile Iron" is, all the parameters the strengths, composition, how it was discovered and so forth are well covered...

Anyone interested can also check out Wikipedia and/or the different standard representatives like AWS for the various engineering specs of the different "iron/steels" used in the manufacture of the NEF shooters.

That is only good for the time being...Remington might decide to change some of the parameters and then all bets are off.



Tim...you might see if NEF would give you some engineering technical information on the composition of their mix...it has a wide range of strengths just as ANY "iron/steel" metal has.

Then put up a sticky for the REASONS WHY NEF uses different compositions for their SB1 and SB2 frames...it might put a stop to the continuing saga of SB1 vs SB2 and what you can do with each...although I doubt it.

Luck

[quickdtoo]

The best info we've ever got from H&R was from Gordon in Gardner on SB2 frames being heat treated investment cast alloy steel which is in the FAQs, and the change on '96-'99 SB2 frames not being eligible for any accessory rifle barrels other than 357 and 44 mag as well as shotgun barrels due to being outsourced, likely for liability reasons related to the change of ownership, not necessarily frame strength. No info on the composition of SB1 frames to speak of, the confirmation that they're ductile cast iron was the result of this thread.

My H&R source no longer works for H&R as of Dec '09, so he's not in a position to get more specs even if he were able to share them, which in the past no one has been publicly willing to do other than what Gordon shared.  I have gleaned barrel material, 1137 for rimfire and shotgun, 4140 for centerfire rifle and 400 series w/magnetic properties for stainless, but that's about it.

Tim