Loadings for Boolits with Gas Checks

[Dogbone13]

Can you use standard loading data for cast boolits when shooting them with gas checks or do you have to reduce the load to account for the increased pressure? Is there some kind of formula to apply?

Thanks for your help!

[tja6435]

Pretty sure Larry Gibson did a pressure test on checked vs plain base and found less pressure with checks.

[Chris S]

You could, up to 2500fps or so, but it's always wise to work up from a bit less than the listed values.

What specific chambering are you working with?

Chris

[Conditor22]

IF they are gas-checkable boolits the load books will have taken this into concideration.

1 you need to find the diamiter of your barrel (either slug the barrel or pound-cast the chamber) [use the search box at the upper right of this page]

2 you'll need to find the diamiter .001-.003 over the barrel size that works best for your gun

3 use the hardness (BHN) that's best for the speed you intend to push the boolit

4 look up load data, start with the lowest load and work your way up to where you get the best accuracy

[gwpercle]

Can you use standard loading data for cast boolits when shooting them with gas checks or do you have to reduce the load to account for the increased pressure? Is there some kind of formula to apply?

Thanks for your help!

No need to change loading data . The load listed for a gas check boolit can be used for a plain based boolit and vice versa ... all other things being equal of course .
If I remember correctly member Larry Gibson did some testing which revealed the gas checked boolit developed LESS pressure than plain based boolits !
Larry G. ...correct me if I'm wrong on this .
Gary

[Bazoo]

Gas checks produce less pressure due to controlling obturation.

[Dogbone13]

You could, up to 2500fps or so, but it's always wise to work up from a bit less than the listed values.

What specific chambering are you working with?

Chris

45-70. 405 gr cast.

[Dogbone13]

No need to change loading data . The load listed for a gas check boolit can be used for a plain based boolit and vice versa ... all other things being equal of course .
If I remember correctly member Larry Gibson did some testing which revealed the gas checked boolit developed LESS pressure than plain based boolits !
Larry G. ...correct me if I'm wrong on this .
Gary

That's just it. I have not been able to find any listed load data specifically for gas checked boolits. Less pressure. Interesting. Thanks.

[Dogbone13]

Thanks guys. Great information. Just what I was looking for. Appreciate it.

[Conditor22]

:There are 3 different loading levels for 45/70 for different strength firearms:
Lightest For 1873 Springfield
Medium For 1886 Winchester & 1895 Marlin
hotest For Ruger No 1 an No 3

You don't want to use load-data for a category above what your gun is rated for.

I'd suggest staying safe and sticking with the lowest category, it should achieve anything you want to do with that gun

I have not seen a need to GC 45/70 boolits even though I have GC molds

[Wayne Smith]

If you are not shooting a trapdoor you are likely to find your shoulder is more sensitive than the gun/barrel is! That is, you will want to stop before you reach any limitations of the gun.

[Dogbone13]

I have several loading manuals from both powder and boolit manufacturers. They all show loads for jacketed and cast boolits, but none of those manuals show loads specifically for cast boolits with gas checks. Unless I'm reading your responses incorrectly, any appropriate load for casts boolits (without gas checks) listed in these manuals will work for boolits with gas checks. Am I wrong? Thanks.

[richhodg66]

I have several loading manuals from both powder and boolit manufacturers. They all show loads for jacketed and cast boolits, but none of those manuals show loads specifically for cast boolits with gas checks. Unless I'm reading your responses incorrectly, any appropriate load for casts boolits (without gas checks) listed in these manuals will work for boolits with gas checks. Am I wrong? Thanks.

If the load works with a plain based bullet, it will be fine with a gas checked bullet of similar design. Vice versa would work too, except, the limits you can push a plain based bullet with good accuracy and no leading is lower than it is with a gas check design.

So, yes, any apprpriate load from a manual for a plain based bullet will work fine with a gas checked bullet of similar weight and design.

The .45-70 with 405 grain lead alloy bullets is very well-plowed ground. You should be able to easily find load data for any design of bullet with any safe powder combination you want without having to try very hard. As stated, mind the level your rifle is and go from there, but I honestly never saw a need to go above Trapdoor levels in the .45-70.

[Dogbone13]

If the load works with a plain based bullet, it will be fine with a gas checked bullet of similar design. Vice versa would work too, except, the limits you can push a plain based bullet with good accuracy and no leading is lower than it is with a gas check design.

So, yes, any apprpriate load from a manual for a plain based bullet will work fine with a gas checked bullet of similar weight and design.

The .45-70 with 405 grain lead alloy bullets is very well-plowed ground. You should be able to easily find load data for any design of bullet with any safe powder combination you want without having to try very hard. As stated, mind the level your rifle is and go from there, but I honestly never saw a need to go above Trapdoor levels in the .45-70.

Thank you. That's exactly the answer I was looking for. Yes, load data is readily available in the manuals I have so I feel I'm good to go ahead and start loading safely.

[richhodg66]

If you're a beginning reloader, just read a lot, ask a lot of questions and double check everything. Don't push the envelope. I have found there are two cartridges out there that really seem to attract guys who want to hotrod them and the .45-70 is #1 in that regard. Just have to shake my head, the .45-70 is powerful even when it's not.

In another thread that's going now, I and several others express that we like 12 grains of Unique as a load in .45-70 and it works beautifully, but I don't think you'll find it in modern load manuals, I got mine from an old Lyman. There's a lot of us on here who like fast powders and light charges and it works great, but there is always the danger of a double charge and 24 grains of Unique would make for a very bad day. I charge mine in a loading block and visually check all of them with a strong light and just the other day, that check caught a double charge and the one I missed that had no powder (wife came in and asked a question). Would have been a disaster if I didn't have that check my Dad ingrained in me for reloading. Everybody has a method, just make sure you do some kind of secondary check before seating a bullet.

[Dogbone13]

Thank you for the information and for the advice. Much appreciated.

Hope you guys have plenty on hand cause Unique is out of stock everywhere.

[Chris S]

"Hope you guys have plenty on hand cause Unique is out of stock everywhere."

If they have it, Trail Boss works very well for light loads in the 45-70 as well. And no way to overcharge, so long as your not compressing the powder.

Chris

[Dogbone13]

Thanks Chris.

[pworley1]

You normally would not need a gas check for the 45 70 unless you are using a Ruger No. 1. My Lyman manuals only list data for gas checked bullets for the Ruger. Shooting the 45 70 is much more enjoyable when kept below 1600'/sec.

[Dogbone13]

Again, thanks for the input/advice.

[Larry Gibson]

No need to change loading data . The load listed for a gas check boolit can be used for a plain based boolit and vice versa ... all other things being equal of course .
If I remember correctly member Larry Gibson did some testing which revealed the gas checked boolit developed LESS pressure than plain based boolits !
Larry G. ...correct me if I'm wrong on this .
Gary

My initial testing did indicate that. However, subsequent testing with other cartridge bullet combinations tend to indicate "it depends"..... Thus like numerous pet theories we used to assume were correct there are variables that can skew measured results one way or the other. The biggest variations are the cartridge type used and the seating depth (not to be confused with the OAL). The biggest variation I've found so far is going to be in handgun cartridges because of their smaller case capacity over larger rifle cartridges. Those variations include bullet design which influences bearing surface and close weight of the bullets within practical consideration. Example; in the 44 magnum with a given load a 240 gr Lee TL SWC seated to the 1st lube groove and the Lee 240 GC'd SWC consistently give higher psi than the heavier 429421 (252 - 255 gr) bullet. Both the Lee bullets seating depth is the same and the psi with a given load are also pretty much the same. The Lee 240 SWC GC'd However, a 429360 PB'd 240 gr SWC gives less psi than all the other bullets because the seating depth is less than the others.

In handgun cartridges the seating depth [with a given load in a given cartridge] appears to be the critical variable that effects pressure the most over GC'd vs PB'd or even with jacketed bullets. In larger regular bottle larger rifle cartridges variation in seating depth and GC'd or PB'd falls within test to test variation and is basically meaningless. In smaller capacity rifle cartridges such as the 22 Hornet, 30 Carbine, cartridges based on the 223 Rem case and other AR length cartridges seating depth can also be a critical factor if approaching maximum pressure loads.

This is why we should follow most all manual suggestions to work up loads watching for pressure signs. The use of a chronograph is very beneficial if developing maximum psi loads or approaching those. If you are getting higher velocities than expected with a load combination then you can pretty much bet you are also getting higher pressures. I do not believe in "fast barrels". Those barrels that give higher velocities with a given load have chamber/bore/ rifling dimensional differences that create higher pressure with that given load/cartridge.