Gas check required at what MV?

[greenjoytj]

At what muzzle velocity can you drive a cast bullet to before it requires a gas check to prevent leading?

I'm looking for a general rule, if there is one.

I'm sure the condition of the rifles bore would play a major roll as to whether or not it could exceed the rule or required a gas check before the rule threshold is reached.

Of course bullet fit to the bore is vital too.

I am driving a 250 gr. Lyman 452664 bullet cast with 20:1 alloy to about 1240fps.
I do get a little leading that is easily removed during regular cleaning without too much effort.
The bullet is lubed with homemade Emmerts Improved and sized to .452" in a Redding lubricant-sizer. Miroku/Winchester M73 45 Colt 24 inch barrel.

[pworley1]

Every gun is different and many factors come in to play, but in general I start using a check at around 1500.

[centershot]

Well, if we're talking handguns, you probably won't need a gascheck. I have shot 250 gr Keith boolits @ 1500 fps from my Contender (lubed with NRA 50-50 lube), no GC and no leading. If it means anything to you, Elmer Keith used 16:1 alloy and didn't use gaschecks. And he was pretty happy with his results!

[MT Gianni]

General rule with good lube is 1500 fps. The caveat is that if a bullet is designed for a gas check it almost always shoots better with one than without one.

[Larry Gibson]

My "general rule" is 1400 - 1600 fps depending on alloy and bullet design along with other variables. I was just recently working up a load with some PB'd 311-232-FNs in my 308 CBC rifle. Unknown what alloy but the BHN was 12. They were lubed with 2400+. At 1380 fps accuracy was excellent with no leading or fouling at all. At 1455 fps key holing (at 50 yards) was evident, group opened from .7" with 1380 fps load to 3.48" with this load. Leading was evident all along the bore. Same bullet but with 18 BHN with same loads went to 1525 fps before giving any evidence of leading.

I regularly push 20 - 1 alloy bullet to 1300 - 1400 fps without leading so given your cartridge, bullet alloy and 24" rifle barrel if the leading is close to the chamber I would size larger. If closer to the muzzle the lube is giving out (or not enough of it). If leading is in entire length of bore or sporadic I'd definitely try another softer alox based lube.

[megasupermagnum]

In handguns I'm not so sure it is as velocity dependent as it is pressure.

[smkummer]

I size all my 45 colt bullets at .454, use lee tumble lube ( even on bullets that are not a tumble lube design such as Lyman) and observe little or no leading in my handguns or colt burgess repro. I am guessing I am getting about 1200 FPS with 9 grains unique and Lyman 454190 in the 20” burgess. I also water quench my wheel weight alloy, so that is getting close to 20 bhn hardness.

[charlie b]

First, I'd go through this and see what they say about leading and how to prevent it.

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

My biggest problems with pistol leading were either too hard a bullet or lack of lube in the bullet grooves (grooves not holding enough lube).

[mnewcomb59]

1:30" twist Rossi lever actions shoot magnum loads just fine without gas checks. I have 3 158 bullets that I use in 357 and by far the least accurate is the Lee 158 SWC GC. It shoots 5 MOA at 100 yards with 2000 fps MV, while the 158-RF at same speed shoots about 3 MOA. My NOE 154 WFN GC is slightly more accurate, about 2 MOA at 2000 fps, but gas checks cost me so much time. Not worried about the cost, but the time it takes to true the bases and seat the check square for minimal gains over PC 6 banger 158-rf.


My Marlin 45 colt 1:38shoots 260s at 1800 fps into 3MOA. I usually use ACWW or AC 2-2-96, but three Rossi 357 rifles shoot the Lee 125-rf in ACRS 9 BHN into 3 MOA at 100 yards for 10 shots at 2100 fps MV with powder coat. The soft lead and high pressure completely obturates the lube groove and slightly cups the base but they durn shoot gud.

Between the velocity, diameter and accuracy, you will never catch me burning 35 grains of gun powder to shoot a 150 gr 30 cal with a gas check to only get 1800 fps. I am getting the same accuracy, same or better velocity, using half the gun powder and I can make 10 plain base powder coated bullets in the time it takes to make one good, square, well seated gas check bullet. If you wanna hunt or get quick success, skip right over the small bores and get yourself a slow twist pistol cal magnum rifle. Maybe I would be interested in a slow twist 30 bore someday like Larry Gibson runs , but at the same time if I had the inclination and cash, I would be hard pressed to not make it a Whelen.

[MT Chambers]

I find that as bore dia. goes down, you need a gc at lower velocity, an example would be the 45/70 which is okay with plain base at 1800 + whereas a .22 cf. doesn't tolerate that speed.

[robg]

I find that as bore dia. goes down, you need a gc at lower velocity, an example would be the 45/70 which is okay with plain base at 1800 + whereas a .22 cf. doesn't tolerate that speed.

i think that sums things up pretty well.i like to use fairly soft boolits so i use gc from about 1200 fps .