Why do we need gas checks

[Cico7]

Q - 1 Why do we need gas checks on molded boolits?
I expect this is a repeated question and there are many replies so if you could point me to a link I would be happy.

Q - 2 If I powder coat a boolit do I still need to lubricate it? again, links are perfect instead of rewriting the book.

Q - 3 Can you suggest a publication on casting?

Thank you.

-Newbie2
Don

[El Bibliotecario]

https://castboolits.gunloads.com/showthread.php?110213-From-Ingot-to-Target-A-Cast-Bullet-Guide-for-Handgunners

The above reference may be where I read the apt comment that gas checks forgive a lot of mistakes, which was my personal experience as a beginning caster of handgun bullets when I knew bupkis about how proper lead hardness and diameter matched to a specific weapon and powder charge can greatly reduce or eliminate the need for gas checks. Gas checks apparently allow higher velocity with rifle bullets. I say 'apparently' because my limited experience with cast rifle bullets has always been with gas check bullets, so I have no standard of comparison.

The Lyman Cast Bullet Handbook is in my opinion an excellent reference.

I personally avoid powdered bullets. I have heard too many stories about how they may cause ovarian cancer.

[Cico7]

:) Cool! Thank you so much.

[Bazoo]

Gas checks are a bandaid for a gun that isn’t dimensionally ideal. So maybe you have a slight constriction at the threads for example. Gas checks are an easy cure.

PCed bullets don’t need gas checks most of the time. They may benefit though.

Gas checks scrape the leading out as they go down the bore. They also allow higher velocity all else being equal.

A publication on the techniques conducive to good casting? I’m not aware of one. The cast bullet handbook 4th is better than others I’ve read. My techniques are partly the same as the books I’ve read and partly what I’ve learned from trial and error. A book called the art of bullet casting from Wolff publication had some good info that helped me.

Howdy and welcome to the forum. Ifn ya need help feel free to reach out to me.

[gwpercle]

You can get by without gas checks in handgun boolits quite nicely .
Elmer Keith disdained them ... Skeeter Skelton used them in hot 357 Magnum loads .

In small bore rifles ... anything under 40 cal. ... they just make load development easier , quicker and more enjoyable ... and I rather like ...easy , quick and enjoyable !

I can't help you with powder coating ... I don't do it . Lithium-Beeswax (Lithi-Bee) Lube has always worked for me so I stick with it .

Buy yourself a copy of the Lyman Cast Bullet Handbook 4th edition ... and read the information chapters preceding the loading data sections ... loads of great info nat you finger tips .
If you can find a copy of the 3rd edition of the Lyman Bullet Casting Handbook ... the information in the chapters preceding the loading data, is completely different and perhaps more valuable ... but only buy a reasonably priced 3rd edition .
Not very many manuals have cast boolit data .
RCBS published their Cast Bullet Manual number 1 in 1986 ... and never published another manual !
It's nice to have but don't pay more than 40-50 dollars for one ... Lyman's are better !
Gary

[Winger Ed.]

Some powders burn hot enough to vaporize a bit of Lead at the bottom/back end of a boolit.

Some of this can and will get deposited inside the barrel as Leading.
Look at a recovered boolit, and sometimes you'll see pits in the base.
It's from the Lead being vaporized by a speck or so of powder imbedded in it and burning during firing.

A gas check prevents this, and grips the rifling enough to get a higher speed without the boolit 'stripping'
or going down the barrel with a little less twist rate than the rifling is cut for.

Sometimes you can see Leading start to build on one edge and the maybe bottom of the groove, and not the other side.
I interpret that as pushing a boolit a little too fast for what it is, and it's trying to strip in the rifling.
Using a gas check would be the first way to stop that.... at least to a point.

[Bazoo]

Oh, and if you PC, no you don’t need to lube it. Though there are those that do lube pc bullets when they are trying push the envelope.

[Bigslug]

When you start getting up into rifle velocities, there is an insane amount of rotational torque getting applied to the bullet as it engages the rifling. Your lead alloy is a plastic material, and when subjected to that torque, the nice, tight fit you had hoped for can turn into gaps, gas leakage around the base of the bullet, plasma cutting lead off the sides of the bullet, lead deposits in the barrel, poor accuracy, and premature baldness.

It can also come in handy at lower velocities when you want to use a softer alloy than would normally be appropriate for the load pressure at hand; for example, if you wanted a hollow point to reliably expand.

El Biblio and Bazoo are correct in that they are also something of a band aid if for whatever reason you don't have full control or knowledge of all the variables. If you have fully nerded out on this process and can lap out a revolver's barrel frame crush, have used pin gauges to determine both bore and cylinder throat diameters, slugged the barrel for groove diameter, and have a good knowledge of what alloy your load needs, you can live without a gas check quite happily until you start creeping up into the 1600 fps range. If, on the other hand, you're just starting to dip your toe in, gas checks are a decent safety harness.

[GhostHawk]

I shoot a lot of loads that are well below 1400 fps that do not have gas checks.

I shoot some that are above 1600 fps that do and get the advantage of no leading to clean and peace of mind.

Depends on the situation.

One of my more fun loads was in the .223rem with the 55 gr bator boolit and used 3 grains of Red Dot and no gas check.
At least as accurate as my Ruger 10/22 at 100 yards they were all minute of squirrel head assuming I was aiming at the eye. 10 out of 10 would have killed the squirrel.
Which for a gas check boolit without gas check or PC I felt was pretty good.

I don't consider it a hard and fast rule, more like good advice. If planning to go over 1400 fps use a gas check.

For 1000 it may not be needed, or it might prevent issues that could otherwise crop up.
But its YOUR call.

[MT Gianni]

Get Veral Smiths book, Jacket Bullet performance with cast bullets. He explains 5 things that checks do.

[fredj338]

IMO, for handguns, gc is just a pita especially if you are PC. I have had them removed from a couple molds. Even running 1400fps in my 357mag with PC & moderately hard alloy, no leading issues. Nope, no extra lube req'd, for PC bullets. I have run PC no gc to 2000fps with decent 100y accuracy in my 6.8/AR.

[FredBuddy]

Cico7:

I powder coat many of my boolits
and avoid using gas checks to save
money. So far I'm up to 1800 fps in a
Marlin 30-30 micrgroove and most
pistol cartridges.

Stop by if you want to discuss more.

[Milky Duck]

so will a skinny wad/piece of card under boolit achieve the same base protection???
.45/70 rifle at middle of chart levels... driving me nuts.

[charlie b]

Yes it can. BPCR folks frequently use wads We used to use poly wads (1/16 to 3/32) instead of gas checks in hot .357mag loads. I don't recommend them for necked cases since the wad 'could' drop into the case. BACO sells poly wads. We used to cut our own from various sources.

[Tim357]

I remember an article in Handloader magazine by John Haviland some time back discussed gas checks. He was lamenting the cost of same, so he made 3 or 4 homemade checks and shot them. I don't remember the issue, but if I run across it at home I'll post it up

Ran across this during a search:

Quote Originally Posted by Maven View Post
tchepone, No, unfortunately I can't recall the date, but possibly within the last 4 or 5 years, and late Spring - late Summer issue.
Maven: Got it! The article is by John Haviland as you said. It is in Handloader #255, the October-November 2008 issue. He covers different materials and rifle & pistol calibers. It is an interesting read. That said, I think much of what was covered in the article has been rehashed here on the forum a few times. For anyone interested in obtaining a copy, I'm sure it is still available from Wolfe Publishing, as a back issue.

I'm not sure about the legality of copying and posting the article here on the forum. I would not be able to do that anyway because mine are all hard cover bound. Perhaps someone with the complete set of Handloader issues on DVD may be able to do it.

I wouldn't consider Haviland's use of different materials as "gas checks" in the true sense of the term, but more like an "over powder" wad that is glued to the base of a bollit. Even his use of aluminum was just a flat disk and not a skirted check as created by the FreeChex and Checkmaker tools. His use was more likened to the Jim Harvey Prot-X-Bore Zinc Washers of years ago. It might be food for thought more than anything else, but interesting anyway.

Thanks for getting me in the ballpark. I really didn't want to search through 27 books of magazines.

[Soundguy]

Another vote for the Lyman cast bullet book.
As has been mentioned..a gas check is great for high velocity..and prevents base cutting..and if your alloy is a little soft..it helps.

[mdi]

Along with the good Lyman Cast bullet Handbooks, another great source of cast bullet info is; http://www.lasc.us/Fryxell_Book_Contents.htm

[Castaway]

Try the below;

http://www.lasc.us/Fryxell_Book_textonly2.pdf

http://www.lasc.us/ArticlesFryxell.htm

[Milky Duck]

thanks Charlie....food for thought definately.

[JonB_in_Glencoe]

You can take 'em
OR
you can Leave 'em.

need more to read, this sticky has some info.
https://castboolits.gunloads.com/showthread.php?41033-The-real-story-on-Gas-Checks

[rintinglen]

If you want to learn about casting, a copy of the Lyman 3rd edition is better. They are available on line
https://www.scribd.com/document/366588877/Lyman-Cast-Bullet-Handbook-3rd-Edition-1980
The only draw back to the 3rd edition is the obsolescence of the load data due to the discontinuance of older powders and the introduction of new calibers and powders.