David Reiss
posted this
31 December 2016
Recently reading Fouling Shots & Cast Bullet back issues, I came across this letter to the editor, which deals with a similar issue with light loads in the .30-06. I will reprint it for those that don't have access to the article, but edited for content.
David Reiss
Preventing Case Shoulder Set-Back (The Cast Bullet issue no. 98 July - August 1992)
Dear Glenn,
Back in October of 1990 I wrote you about a problem I was having with light loads pushing the shoulder back on my .30-06 cases................................... Your advice was to make up some loads using jacketed bullets jammed against the lands. This solution did not appeal to me for three reasons: 1) I did not have any suitable bullets, 2) my supply of 4895 was about gone, 3) and did not want the job of getting the copper out of the bore so I could shoot cast bullets again..............................
As you pointed out in your letter, the case expands as the powder pressure builds up and grabs the chamber wall. If the pressure is too low, friction will hold the case against the wall and the case will not blow out properly. It seemed that one possible solution to this problem would be to reduce the friction between the case and chamber wall. Case lube or oil would probable work but are too messy and would pick up dirt. The best solution would be some kind of dry non-sticky lube. It happened that I had a can of silicone spray lube handy and tried it on a few cases. The stuff dried quickly and gave the cases a very slick non-sticky coating.
I had 40 rounds on hand using 20 grs. of SR4759, a 205 gr. bullet and cases with the shoulder pushed back. So I decided to give the silicone lube a try. It worked like a charm. The cases were nicely blown out. This trick has been tried several times now and has never failed to work. This is how I spray the cases. A number of them are spread out on a paper towel and sprayed. They are then turned 180 degrees and sprayed again. I don't know how many firing the lube job is good for, bt it is not necessary to lube after every firing. My guess at this point is to lube after 3 or 4 firings. It may not be a good idea to shoot to shoot lubed cases with full loads. The thrust against the bolt face might be excessive. (Glenn Latham's Note: Definitely do not use lubed cases with full loads!)
The accuracy of my loads still leaves a lot to be desired and I don't know what the problem is. A sinclair case concentricity gauge has been ordered and may shed some light on the subject. If I come up with anything interesting I will pass it on.
Sincerely,
James F. Saltsman
P.S. I have used the silicone trick since I wrote this letter and it is still working fine.
David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
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