Gas Check vs Plain Base....Loading Question

[wtfooptimax200]

Good evening everyone....I have been lurking here for quite a while and just joined. This place is full of amazing information. I feel well prepared to begin casting. I do have one question to which I have not been able to find a clear answer......I have purchased several manuals attempting to acquire data for loading my newly acquired 480 Ruger SRH. I am wondering if GC loading data can be cautiously applied to plain base bullets (provided there is no leading). I assume that GC bullets would result in slightly higher pressures than PB, is this true? I would also assume that applying PB data GC bullets may result in elevated pressures. Any information is appreciated.

Thanks in advance.

[peerlesscowboy]

I'm guessing the difference (if any) would be so small as to be inconsequential. Other things such as crimp groove placement/seating depth would be a bigger factor. ........I think?

John C. Saubak

[geargnasher]

Generally speaking, it should be perfectly safe to substitute unchecked or plain-based boolits for loads that were developed for checked boolits provided you start with the minumum published data and work up. You might not like the results, since many loads for the .480 are quite stiff and gas checks are practically required for full-house loads. That means that the heavy, slow-burning powders might not light well with your checkless boolit, and the boolit might fail structurally during "launch" creating gas blowby which leads to leading and wild groups. If you're in the range of Unique to 2400, you should be fine substituting data, but Lil-Gun, 296/H110, 4227 etc. might do better with a check.

Gear

[PacMan]

Recently i have read two other members refering to the same thing about GC vs PB and presure.I have no way to prove it but i would think that the GC bullet would decrese presure if anything. One member sugested that the tiny bit of hard copper would cause higher friction.Someone would have to prove that to me in a sientific way for me to belive it.

One of the jobs of a GC is to keep the base of the bullet from distorting and to limit obturation. I would come closer to beleiving that obturation would raise presure faster.Once again that is only my thoughts and have no way of proving it.
Dwight

[onondaga]

Another generalization is that plain base bullets that don't fit well enough to be driven to obturate lose pressure by gas jetting. Plain base bullets driven harder than they need to be driven for obturation are at risk of detrimental deformation that also allows gas jetting. Gas checks are a standard remedy to extend the velocity/pressure range of boolits and they enhance accuracy by uniforming boolit bases with a material stronger than lead alloys. Gas checks also have a scavenging effect by their scraper action that can keep leading under control for a wider span of alloy hardness than is possible with plain base boolits.

Gas checks are an added expense and require additional steps in loading. Not using them when they are necessary for a load ends up being more expensive and frustrating to hopes of accuracy.

I have seen no excellent ten shot group targets from shooters that use bullets designed for gas checks and don't put gas checks on . Doing that leaves a pathway for gas jetting to begin where the under bore size gas check shank of the bullet transitions to the over bore size driving band. A gas funnel is created when the check is absent. If you cannot get a good 10 shot group, I don't consider that accuracy.

Gary

Gary

[Bass Ackward]

I assume that GC bullets would result in slightly higher pressures than PB, is this true? I would also assume that applying PB data GC bullets may result in elevated pressures. Any information is appreciated.

Thanks in advance.


It only matters if it does. Things like bore condition and hardness and lube. So a PB "can" act like brake pads on a car if pressure raises above hardness and the lube doesn't perform. So how do you plan to shoot them?

Truth is, you can't always tell and it's the unforseen that bites you. So that's why you always start low and work up.

[thunderthud]

my experience with PB boolits in just about any given handgun caliber is with an identical boolit weight the PB boolit vs. the jacketed uses about the same or a bit less (ususally a grain or a little under) powder with usually the close to same pressure and fps. It would seem a jacketed boolit doesn't take as much pressure to get it out of the barrel. The loads I looked up came out of Modern Reloading by Richard Lee.

[44man]

Good evening everyone....I have been lurking here for quite a while and just joined. This place is full of amazing information. I feel well prepared to begin casting. I do have one question to which I have not been able to find a clear answer......I have purchased several manuals attempting to acquire data for loading my newly acquired 480 Ruger SRH. I am wondering if GC loading data can be cautiously applied to plain base bullets (provided there is no leading). I assume that GC bullets would result in slightly higher pressures than PB, is this true? I would also assume that applying PB data GC bullets may result in elevated pressures. Any information is appreciated.

Thanks in advance.
I made one GC mold for my .475 and it has to use 1/2 gr less powder then PB but it is due to a slight difference in the boolit, not the GC.
All of my other boolits are PB for the .45, .475, .500 JRH, .500 Linebaugh, .50 Alaskan and 45-70.
All I use is water dropped WW metal. I get no leading and the BFR revolvers will all do 1" at 100 yards.
I was making my molds for the 45-70 with GC's because of the velocity until I found PB shoots exactly the same. I found there is no need for a GC in any of my revolvers if the boolit is tough enough.
The Linebaugh is Whitworth's little beast :mrgreen: with so much recoil it ripples to my toes so I can only do so-so with it from the bench. I refuse to shoot his Alaskan with the grips it has because I don't want to ruin my hand! :drinks: But both do fine for him with PB.
A fine boolit for the .480 is the Lee 400 gr and it is a PB.
I am never going back to GC's unless I need a softer boolit for deer in my 45-70, softer needs one.
The .480 does not need soft for hunting and none of the other calibers I listed do either.
A GC only stops skid at the base band by grabbing the rifling but you can do the same with a tough enough PB.
You will read a lot about gas leakage but it only happens with a boolit too small for the bore or one that is too soft and skids the rifling too far to open gas channels. Don't worry about the boolit while in the throats.
Gary said some good stuff except for one thing. If the boolit is too soft and skids, a GC can also skid and you can lead the bore and lose accuracy too. If you leave a GC off of a boolit designed for one you create 2 problems. You shorten the drive area so the boolit does not have enough to completely halt skid and you can make a mismatch to the twist rate. If the boolit design has enough drive area before the GC to halt skid you can leave it off but make the boolit too soft so it keeps skidding and you are back to square one.
Understand what the GC REALLY does and how alloy choice can change what you need, a PB will do what you need.

[44man]

my experience with PB boolits in just about any given handgun caliber is with an identical boolit weight the PB boolit vs. the jacketed uses about the same or a bit less (ususally a grain or a little under) powder with usually the close to same pressure and fps. It would seem a jacketed boolit doesn't take as much pressure to get it out of the barrel. The loads I looked up came out of Modern Reloading by Richard Lee.
That sounds backwards. Jacketed has more friction and needs LESS powder to raise pressures.
Given the same seating depth, cast can use more powder and still have less pressure then the J word stuff.
Either way, all loads MUST be worked for each bullet or boolit.

[felix]

Also, the boolit has to be long enough to bridge the cylinder with the grooves to get the supreme performance 44man is talking about. His boolits are long enough to make the BFR's fast twist valid for the bore size, and his cylinder loose enough to allow any needed flex to make the bore alignment exquisite. ... felix

[Packy]

I shoot the lee 400 in my Taurus raging bull. The Mix is 50/50 stick on, clip on ww water dropped. sized at about 4775 had to ream out the rcbs sizer to get this. 20 grains of 296 is the charge, and they shoot well at 100 yds. No leading at all. Have tried the lee 325 and haven't has much luck with it.