Newbie gas check question

[DeanoBeanCounter]

In layman's terms if possible. What are the pros and cons and limitations of gas checks? :confused:

[DLCTEX]

Pro: aids in preventing flame/gas cutting of the boolit. Acts as a scraper to remove fouling. May let you increase velocity.

Con: can fall off and become an obstruction if boolit is seated deeply. Can damage chronograph if it comes off in flight. If not properly seated, can cause offbalanced boolit. Adds a step in preparing boolits= expense and time. Have to be used with molds with gas check shanks. Fit from brand to brand can be a problem. Requires seating/sizing device.

Limitations: doesn't compensate for poorly fitted boolits. Won't allow pushing velocity to J word limits.

I'm sure there are more, but this is a start. DALE

[arkypete]

Everything Dale said.
Plus
I use the gas check for all loads above those achieved by black powder.
I've not chronographed any of my loads in my 30-06, 375 Whelen, 243 Win, or 405 Win, but I used the same data that I used for red boolets.
There's a careful investigative process that I go thru, involving the alloy, heat treatment, boolet diameter, powder, cartridge length, case neck diameter.
All of my gas checks are annealed to soften them so they grip the boolet base, I believe they stay on the boolet, as I never found one any place other then the back stop. But some of them I never found and I don't really go looking for them, either.
Jim

[Maven]

DoBC, Let me add to Dale's post. Gas checks (hereafter GC's) allow you to drive a bullet cast of a fairly soft alloy such as wheelweights (BHN ~8-9) faster than you can without them. Apparently they also greatly strengthen the base of the [cast] bullet, thus enabling it to better withstand higher pressure and velocity. To the extent that the last two are accomplished, accuracy will improve. As Dale already mentioned, a well-fitted GC'ed cast bullet will reduce bore leading. Please understand that adding a GC doesn't automatically improve accuracy and that plain-based cast bullets have an enviable reputation with respect to accuracy.* As for the cons of GC's there is the expense of the checks themselves as well as that of some kind of device to seat them and possibly to lubricate and size them.** Then too, adding and seating a GC is an extra reloading step that may be seen as a "cost" since it does take time (not all that much).

*Lyman #311403 is one such example

**GC seating & sizing devices can be homemade or purchased. Lee Precision, Lyman, RCBS, Saeco, (in ascending $$$ order), et al. produce & sell them.