In loading hard cast bullets where do you start to need gas checks? Rifle or pistol?
Jim
Jim
Jim n Iowa
Far as I can tell, gas checks do three things.
First, they give a solid even base to bullets...at least is even if the gas check is applied evenly and not "cocked". An even solid uniform base is an aid toa ccuracy...can have that without gas checks, but gas checks seem to make up for some small imprefections.
Second, they "check gas"...they offer a bit better seal so gas has a much harder time passing the gas check and eroding the sides of the bullet. Even after the bullet is run through a sizing die, the gas check is a bit larger in diameter than the bullet itself (the gas check material has more spring back).
Third, they act a bit like base wrenches..the grip of the gas check and bullet base is greater than the sheel strength of the lead bullet alone, so if the bullet starts to "strip" in the rifling, the gas check offers more resistance to stripping.
There is a 4th item, that many people firmly belive in: they protect the base from the effects of the high pressure/temperture gas of buring powder. It is debatable...and even if it does do this, it's the least imporatant item a gas check does (becasue a card or fiber wad would do it just as well if that's ALL a gas check did).
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Don't use them in 95% of my shooting. Do use them in centerfire rifles moving over 1800 to 1900fps...or if I desire a handgun load traveling over 1400fps. GEneraly, once I reach 1400fps in a revovler (that 1000fps isn't engraved in stone, but is a good ball-park figure) or 1800fps in a rifle, if I want more power will switch to a heavier bullet rather than push them any faster.
Guess that's part of the reason I'm a big-bore cast bullet believer ...if i'm going to toss it out there at 1800fps or less, then the only way to gain power is by bullet weight...and there are strict limits on how heavy a .308" bullet (or whatever "small bore" you pick as an example) can wrok in a given barrel.
First, they give a solid even base to bullets...at least is even if the gas check is applied evenly and not "cocked". An even solid uniform base is an aid toa ccuracy...can have that without gas checks, but gas checks seem to make up for some small imprefections.
Second, they "check gas"...they offer a bit better seal so gas has a much harder time passing the gas check and eroding the sides of the bullet. Even after the bullet is run through a sizing die, the gas check is a bit larger in diameter than the bullet itself (the gas check material has more spring back).
Third, they act a bit like base wrenches..the grip of the gas check and bullet base is greater than the sheel strength of the lead bullet alone, so if the bullet starts to "strip" in the rifling, the gas check offers more resistance to stripping.
There is a 4th item, that many people firmly belive in: they protect the base from the effects of the high pressure/temperture gas of buring powder. It is debatable...and even if it does do this, it's the least imporatant item a gas check does (becasue a card or fiber wad would do it just as well if that's ALL a gas check did).
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Don't use them in 95% of my shooting. Do use them in centerfire rifles moving over 1800 to 1900fps...or if I desire a handgun load traveling over 1400fps. GEneraly, once I reach 1400fps in a revovler (that 1000fps isn't engraved in stone, but is a good ball-park figure) or 1800fps in a rifle, if I want more power will switch to a heavier bullet rather than push them any faster.
Guess that's part of the reason I'm a big-bore cast bullet believer ...if i'm going to toss it out there at 1800fps or less, then the only way to gain power is by bullet weight...and there are strict limits on how heavy a .308" bullet (or whatever "small bore" you pick as an example) can wrok in a given barrel.
If the design calls for a gas check, use it. Its been proven that a bullet with a gas check groove is more accurate when you use them vs if you dont. As for plain based vs gas checked bullets, well its hard to say really. For pistols i prefer plain based keith style bullets in every caliber i can get my hand on. Their proven designs, work well and are very accurate. Only rifles i cast for are my 444 marlin and 45-70...both get a diet of gas checked 325 grain bullets for the 444 and 400 grainers for the 45-70. In rifles where the velocity is usually greater i tend to get a bit less fouling with gas check design bullets. My 444 for example: Loaded to nearly identiacal specifications, 250 grain plain based keith bullets foul my bore signifcantly faster than a 250 grain(or close to) gas checked design. Both are nearly identical in hardness, used the same powder, primers, cases. Now not every gun will be the same and theres a million factors in terms of accuracy to be acheaved. Accuracy between the two is neglegable with a good load...i can load up plain based bullets to shoot just a well as and gas checked one. It just depends on what your gun likes, whats available to you and how much time and effort your willing to spend to make your gun shoot correctly.Jim n Iowa said:
No one has yet been able to convince me that the advantage of gas checks is that they protect the bullet from 'hot gases' or 'erosion', thereby eliminating leading.
I am firmly convinced that any benefits they have are due to their providing the same service that a 'scraper ring' does for a engine piston. In other words, they follow behind the bullet and scrape off all the crud that was already deposited by the bullet body so that there will better shot to shot uniformity of bore condition.
I am firmly convinced that any benefits they have are due to their providing the same service that a 'scraper ring' does for a engine piston. In other words, they follow behind the bullet and scrape off all the crud that was already deposited by the bullet body so that there will better shot to shot uniformity of bore condition.
Real simple - if you have a perfect bullet base, and perfect bore, then no, you probably don't need them.
Any imperfection in either lets powder gasses squirt past. Then you basically have created a cutting torch.... the hot gasses carry molten lead with them, mixed with bullet lube (think 'flux'), and solders all of this mess to the inside of the bore.
Why is the bullet base more important on this account than the driving bands farther up the bulllet? Because as the escaped gasses expand, they'll cool down (ideal gas law). Plus, they'll impart some heat energy to the bullet as they go by, further cooling them. Cool them off enough, and they can't melt the bullet metal anymore.
The copper gas check can absorb a lot of heat before it melts.
I agree that the gas check also can physically scrape lead deposits from previous shots, but if that was all it did, we could put them on the bullet nose for the same effect.
Any imperfection in either lets powder gasses squirt past. Then you basically have created a cutting torch.... the hot gasses carry molten lead with them, mixed with bullet lube (think 'flux'), and solders all of this mess to the inside of the bore.
Why is the bullet base more important on this account than the driving bands farther up the bulllet? Because as the escaped gasses expand, they'll cool down (ideal gas law). Plus, they'll impart some heat energy to the bullet as they go by, further cooling them. Cool them off enough, and they can't melt the bullet metal anymore.
The copper gas check can absorb a lot of heat before it melts.
I agree that the gas check also can physically scrape lead deposits from previous shots, but if that was all it did, we could put them on the bullet nose for the same effect.
Got bored one summer (about three years back) and had a pile of good 130gr. .310" plain based bullet on hand.
So decided to do four tests:
1. plain based
2. plain based with a card wad under
3. plain based lathed to a gas check shank and gas check seated and crimped (but using a .310" sizer so as not to size the bullet)
4. plain based lathed to a gas check and gas check applied by hand with no sizing at all.
(Took the longest time to make a collet that would hold a .310" bullet solidly, not mark or distort it, butr allow lathing that gas check base.)
Used a very accurate .308 (first year Remington PSS...one of the green park.ed 5-grooved ones).
Detils are complex, but the genralk out come wasn't.
Past 1400fps the plain based bullets were losing accuracy. Adding a card wad helped a little bit, but by 1500 they were done. In neither case was leading a casue of initial inaccuracy...would lead PAST the point where accuracy sucked, but accuracy sucked well be fore leading became a problem. Crimped and uncrimped gas check didn't make any difference in this barrel, they shot well until 1950fps.
A lot of recovere bullets...all showed some slippage as speed increased...the plain based slugs that were wild and leaded showed fuyll slipage all the way to the base (not stripped...just that the land impressions in the bullet were WIDER at the base than the actual width of the lands). SO slippage didn't seem to hurt...so long as the back 1/3 of the bullet held engravemnt widths near to the actual width of the lands, no slippage, no gas leak, no real accuracy loss.
The gas checked bullets would show the same slippage (After all, was the same alloy) but so long as the rifling markes on the gas check were the same diameter as the actaul land's, would shoot well. Some of the recoverd gas checked bullets that did shoot widly (above 1950fps) showed slippage of the gas check OR rifling engravment larger than the actual land width (most of them were too tore up from impact to get dood readings, but that's waht was indicated by the ones that were recovered in measuring shape).
OF coures, if the alloy were harder the slippage would have been delayed to higher velocity...andnif softer would ahve happened eariler....but I wasnt doing this test twice.
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Measuring the uncrimped gas check found that the gas check runs about .322" at it's widest uncrimped lip. Seated and then pulled, it measures .318" A(and leaves a bit of a visible "ring" in the neck that can bee sean when seated).
SO...trotted out a .303Brit. This one has a .303" bore and .314" grooves, but it's a two-groove barrel.
Just tested palin based vs. non-crimped gas checked bullets. May as well not have bothered with the plainbased bullets...started leading from the get-go and never shot well at .310" (gas blow by). The .310" ones wearing .318" gas checks (at least the lip measured .318") shot FINE to about 1500fps....then scattered to the winds.
One of the widl plainbased bulelts was recovered. Where ther should have been goove's, there were erosiopn channels..deep full length eroded areas where gas had not only by passed, but had gas cut deep lines as it squeezed past the bullet in those deep grooves. PLATED the rifle bore in dry gray leading.
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DOes a gas check keep a bullet bazse form the effects of heat?...yes. Waht I am not sure about isa if ther rifling produces long thin "fins" as the lands drag bits of lead backwards from the base. A gas check wouldn't allow this finning...and belive the fins would be much more suseptable to melting as they (1) have more surface area expoded to the heat of the gas (3) are distant from the main lead body, and unable to conduct heat to that larger body fast enough.
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Sorry guys...read this and it's full of typos...but it the ideas stillg et though, so i'm not proofing it.
So decided to do four tests:
1. plain based
2. plain based with a card wad under
3. plain based lathed to a gas check shank and gas check seated and crimped (but using a .310" sizer so as not to size the bullet)
4. plain based lathed to a gas check and gas check applied by hand with no sizing at all.
(Took the longest time to make a collet that would hold a .310" bullet solidly, not mark or distort it, butr allow lathing that gas check base.)
Used a very accurate .308 (first year Remington PSS...one of the green park.ed 5-grooved ones).
Detils are complex, but the genralk out come wasn't.
Past 1400fps the plain based bullets were losing accuracy. Adding a card wad helped a little bit, but by 1500 they were done. In neither case was leading a casue of initial inaccuracy...would lead PAST the point where accuracy sucked, but accuracy sucked well be fore leading became a problem. Crimped and uncrimped gas check didn't make any difference in this barrel, they shot well until 1950fps.
A lot of recovere bullets...all showed some slippage as speed increased...the plain based slugs that were wild and leaded showed fuyll slipage all the way to the base (not stripped...just that the land impressions in the bullet were WIDER at the base than the actual width of the lands). SO slippage didn't seem to hurt...so long as the back 1/3 of the bullet held engravemnt widths near to the actual width of the lands, no slippage, no gas leak, no real accuracy loss.
The gas checked bullets would show the same slippage (After all, was the same alloy) but so long as the rifling markes on the gas check were the same diameter as the actaul land's, would shoot well. Some of the recoverd gas checked bullets that did shoot widly (above 1950fps) showed slippage of the gas check OR rifling engravment larger than the actual land width (most of them were too tore up from impact to get dood readings, but that's waht was indicated by the ones that were recovered in measuring shape).
OF coures, if the alloy were harder the slippage would have been delayed to higher velocity...andnif softer would ahve happened eariler....but I wasnt doing this test twice.
-------
Measuring the uncrimped gas check found that the gas check runs about .322" at it's widest uncrimped lip. Seated and then pulled, it measures .318" A(and leaves a bit of a visible "ring" in the neck that can bee sean when seated).
SO...trotted out a .303Brit. This one has a .303" bore and .314" grooves, but it's a two-groove barrel.
Just tested palin based vs. non-crimped gas checked bullets. May as well not have bothered with the plainbased bullets...started leading from the get-go and never shot well at .310" (gas blow by). The .310" ones wearing .318" gas checks (at least the lip measured .318") shot FINE to about 1500fps....then scattered to the winds.
One of the widl plainbased bulelts was recovered. Where ther should have been goove's, there were erosiopn channels..deep full length eroded areas where gas had not only by passed, but had gas cut deep lines as it squeezed past the bullet in those deep grooves. PLATED the rifle bore in dry gray leading.
----------
DOes a gas check keep a bullet bazse form the effects of heat?...yes. Waht I am not sure about isa if ther rifling produces long thin "fins" as the lands drag bits of lead backwards from the base. A gas check wouldn't allow this finning...and belive the fins would be much more suseptable to melting as they (1) have more surface area expoded to the heat of the gas (3) are distant from the main lead body, and unable to conduct heat to that larger body fast enough.
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Sorry guys...read this and it's full of typos...but it the ideas stillg et though, so i'm not proofing it.
Back in my salad days when I was real poor,I used to use nothing but home cast bullets in my .357.
I used the Lyman U328156 gas check bullet mold exclusively.This bullet uses a gas check and it is installed before you size the bullet.
Whether the gas check design is better - I don't know.I do know that I never encountered any barrel leading with that design during those days even though I went thru over 10 boxes of gas checks (1000 per box).
I used the Lyman U328156 gas check bullet mold exclusively.This bullet uses a gas check and it is installed before you size the bullet.
Whether the gas check design is better - I don't know.I do know that I never encountered any barrel leading with that design during those days even though I went thru over 10 boxes of gas checks (1000 per box).
Great thread on a great board I just stumbeled across.
I've been hacking around with cast bullets--- and have even cast, loaded, and shot about 5,000 pounds of them in the last 20 years--- with and without gas checks. Mostly in .45ACP and .30cal rifle.
In the replies to your post, after all these years of digging around trying to discover more and more on this subject; I have learned a couple of things. And, even found a person who would believe the world really is flat,,,,, just because he thought it was, and refused to be confused with facts.
I've been hacking around with cast bullets--- and have even cast, loaded, and shot about 5,000 pounds of them in the last 20 years--- with and without gas checks. Mostly in .45ACP and .30cal rifle.
In the replies to your post, after all these years of digging around trying to discover more and more on this subject; I have learned a couple of things. And, even found a person who would believe the world really is flat,,,,, just because he thought it was, and refused to be confused with facts.
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