Uneven GC Skirt Length

[detox]

My Lyman .35 gas checks have uneven length around skirt (varies about .005"). Who makes a precise gas check with even length skirt?

[MUSTANG]

With a lot of attention to detail, anyone on this site who uses either the Pat Marlin or FreeChecks gas check tools.

[Dale in Louisiana]

I do! Freechex III and some of Yonky's soft aluminum strips and a little care to make sure that the strip is all the way back in the feed notch on the tool.

Of course, I only do .30 cal and 8mm.

Like many other things in handloading, there are tools available and YOU get to control the quality.

dale in Louisiana

[Blammer]

I sell some.

check out blammersboard.com

[35 shooter]

I may be doing something wrong but but i've noticed on some of my homemade checks a bit higher on one side with the recommended material size. I was told by the maker of the tool that was normal to see that sometimes because of how the tool is made a little more open on the feed side to keep material from getting stuck in the die. He also said it wouldn't affect accuracy. Anyway it's barely noticeable and so far his accuracy prediction has held up. The thickest material i've used so far is .004" thicker than recommended and is predictably high sided because of that but so far it shoots the best. Got a 1 inch group right off the bat with that very check @ 100 yards which is the same i get with hornady checks in the same load. Having said that i have to say when using correct size material for the most part it does make even sided checks and seems to do better with use. Also noticed when run thru the sizer even the thicker check material kind of evened up when seated. Boolit holes in paper showed no signs of yaw. I'm impressed with the little Free-ChexII hand tool. With the proper material the checks look better than factory checks to me.

[338RemUltraMag]

I have 35 Cal checks for 19 dollars shipped.

[MUSTANG]

Detox and 35shoooter:

See the following thread (post #8) that provides some dimensions, tolerances, and a schematic type drawing for gas checks:


http://castboolits.gunloads.com/showthread.php?11997-Gas-Checks-vs-Shank-Size

[detox]

Blammer and 338UltraMag, What are the demensions of your .35 caliber gas checks

[w5pv]

Does it matter after the powder charge hammers the gas check in place?Does it affect accuracy?I cannot tell that it does in my shooting.If some one can tell me I would appreciate it.All of this takes place in a nano-nano second during the trip down the barrel.

[detox]

Does it matter after the powder charge hammers the gas check in place?Does it affect accuracy?I cannot tell that it does in my shooting.If some one can tell me I would appreciate it.All of this takes place in a nano-nano second during the trip down the barrel.

You may be talking about uneven seating. I am talking about uneven side skirt length. This will put bullet more out of balance down range...especially at 100 yards

[w5pv]

Ok ,I see where your concerns are.I was trying to find out for my own info because I really didn't know.I can see where uneven gas check side length could affect down range performance.

[35 shooter]

Detox i think you have a valid concern about any imperfection and the effect of downrange imbalance and possible affect on accuracy and i am too. I'm running tests now as i can on this very thing although hunting season's holding that up somewhat. I tend to be brutally honest about results too. At this point i can honestly say i got the same accuracy as usual @ 100 yards with a obviously high sided check, once i found the thickness in material that the rifle seemed to like. What i don't know yet is what happens when that same boolit slows down further down range? The man who made the dies said the imperfections of the boolit itself both internally and externally would have more effect than the small effect of such a check and that makes sense too. As i said in the above post , i noticed that when seating checks they tended to even out more so maybe upon firing and under that kind of pressure they iron out evenly? I'll feel better about it when i can look at some after firing and shoot at longer ranges. The effects so far are nil. Still a legitimate concern though. I'm sure someone here has already done that kind of testing and just hasn't posted on it.

BTW the high sided checks are my fault for using thick material not the fault of the tool.
Still hoping i can find a thinner material the rifle likes and then make a uniform check.
I have a contrary rifle so naturally it likes something it shouldn't so far.

[WILCO]

My Lyman .35 gas checks have uneven length around skirt (varies about .005"). Who makes a precise gas check with even length skirt?

You can easily make one of my "Gas Check" trimming tools to fix the ones you currently have:

http://castboolits.gunloads.com/showthread.php?83357-Disk-Maker-GC-Forming-Die-and-GC-Trimmer

[tjones]

You can easily make one of my "Gas Check" trimming tools to fix the ones you currently have:

http://castboolits.gunloads.com/showthread.php?83357-Disk-Maker-GC-Forming-Die-and-GC-Trimmer

Simple, ingenious, when there's a will there's a way! Brovo.

[WILCO]

Simple, ingenious, when there's a will there's a way! Brovo.

Thank you Sir!

[detox]

You can easily make one of my "Gas Check" trimming tools to fix the ones you currently have:



Maybe i could glue several to a flat surface (small piece of glass) using 3m spray contact cement. Then block sand skirts even using 600 grit wet or dry paper...measuring as i sand. I could glue sandpaper to piece of scrap MDF board using the spray contact cement. I know i could sand 100 at one time. The contact cement could be removed with some type of solvent.

Maybe alox would work at holding gas checks while sanding. I could remove dried alox by soaking glass and checks in mineral spirits.

[WILCO]

Maybe i could glue several to a flat surface (small piece of glass) using 3m spray contact cement. Then block sand skirts even using 600 grit paper...measuring as i sand. I could glue sandpaper to another piece of glass using the spray contact cement. I know i could sand 100 at one time.

The beauty of the gas check trimmer is that the washer thickness does the "measuring" for you and it'll only take a pass or two on the file to square them up. In a few minutes, you can do any amount you'll need.

[35 shooter]

WILCO thanks for the answer and detox thanks for asking it. So simple and easy... now a trip to the hardware store tommorrow. I have now read back through 50 pages on the gas check site but i had missed that one i guess. Cast boolit members always come up with an answer.....thanks again!

[wistlepig1]

Wilco, great idea, I have no shame about stealing a great idea.:smile::smile: Too the shop!

[35 shooter]

WILCO i tried it out today and it worked perfect. The skirts were same height all the way around. I just super glued a nut to the washer to try it out. Now to weld it and make it a permanent setup.:smile:

[detox]

Here are 100 38 caliber gas checks glued (light mist coat) to flat MDF board using 3M 77 contact spray adhesive. Checks were laid out on paper with bases facing up. Then i sprayed adhesive on base of checks and seperate block of MDF wood. I then aligned then laid MDF over checks to make contact. I made sure all check were laying flat by pressing each check down using pencil eraser. Now skirts will be block sanded evenly using fine wet or dry paper. After sanding gas checks will be removed then soaked and washed in mineral spirits to remove adhesive.

The adhesive cannot be cleaned off the MDF wood. So flat glass or something else will be better to use. I quickly tried the MDF just to see if this will work. Sand paper will be glued or taped to another perfectly flat surface and checks will be sanded evenly

[detox]

Checks are sanded evenly flat using 220 paper taped to glass stove top. All Skirt lengths now measure .060". Skirt edge is very sharp and should "scrape barrel" better.

When sanding be sure to sand just enough to remove high spots

[detox]

I removed checks from MDF block using sharp puddy knife, soaked and agetated checks in mineral spirits to remove adhesive (clear soda bottle), then tumbled in dry media.

[wistlepig1]

Wico, I made one of your check skirt tools and used it. It worked well and one thing I noticed was the the fileing causes a "burr" that helps grip on the check shank. That is a good thing! Had you noted that? Martin

[detox]

Bullet shank size can vary. I have one bullet with a shank size of .341 and another that measures .346. The .346 size is much harder to seat without shaving lead. The gas check must be flared slightly wider to prevent. This requires a custom flaring tool that i must make.

[.22-10-45]

This lopsidedness of gas checks has bugged me for years..why can commercial jacket makers supply precision jacket blanks for bench-resters and yet they can't seem to punch out a uniform height little cup? And although it would probably take a very accurate target rifle to notice, I do believe an uneven height check...at the very moment the bullet base starts to clear muzzle..will allow high pressure gas to escape on the short side affecting bullet flight.

[338RemUltraMag]

This lopsidedness of gas checks has bugged me for years..why can commercial jacket makers supply precision jacket blanks for bench-resters and yet they can't seem to punch out a uniform height little cup? And although it would probably take a very accurate target rifle to notice, I do believe an uneven height check...at the very moment the bullet base starts to clear muzzle..will allow high pressure gas to escape on the short side affecting bullet flight.

I agree about the check height, now I must say my checks have a uniform wall height. But the bullet exiting the bore will be most effected by the base of the check as the walls have cleared before the seal is broken. This is why a lopsided (unsquare seated check) is so detrimental to accuracy.

[detox]

Here is my .358 caliber gas check flaring tool i made from RCBS top punch. It mounts in my RCBS Lubri-matic. I chucked top punch in fast spinning drill press and ground tip to a taper...checking gas check fit as i ground and polished. Finer polishing will help prevent gas check from sticking to tool.

I have a couple of RCBS moulds that have bigger gas check shanks that measure .346 so this will help make seating checks much easier without shaving lead.