Question about screw size for original Pro-Melt

[Walter Laich]

I was going to replace the screw that holds the nozzle shut-off pin to the handle

RCBS' directions say this is: #81115 Round head screw 5/40 x 3/8

Now I'm guessing the 3/8 is 'of an inch'

But what in the world is 5/40 ????

I took the shut off pin to the hardware store and the threaded hole is somewhere between 4-40 and 6-32 as well as also not being a metric thread either.

thanks in advance

[BorderBrewer]

Hi Walter,
PM sent.
Thanks,
BorderBrewer

[fc60]

Greetings,

5-40 translates to a number 5 sized screw (0.125" nominal outside diameter) with 40 threads per inch.

The 3/8 says the length of the screw from under the head to the end measures 3/8".

#5 screws are not common. RCBS might still have a few laying about. Give them a telephone call.

Cheers,

Dave

[Idz]

5-40 is a standard but not so common UNC screw size. The screw thread diameter is 1/8"

[Walter Laich]

just got a reply from RCBS--they are sending me one

It's that I've never heard of these before--learning something new everyday

I know 4-40 and M4 . . . and now I know another way to represent sizes

[gwpercle]

just got a reply from RCBS--they are sending me one

It's that I've never heard of these before--learning something new everyday

I know 4-40 and M4 . . . and now I know another way to represent sizes

I have gone to quite a few hardware stores and not found gun screws , screws for pistol grips , bolts for shotgun butt stock ... even went to a Fastener Supply Business that swore they had every fastener made ... they couldn't match the bolt for the shotgun butt stock and had to eat crow when I told them the shotgun was a Steven's single shot ...not some foreign made European brand .
Seems like manufacturers like to use uncommon fasteners just so we can't get hardware store parts easily ... I think it may be a conspiracy .
Glad you found a free part ...
Gary

[ulav8r]

just got a reply from RCBS--they are sending me one

It's that I've never heard of these before--learning something new everyday

I know 4-40 and M4 . . . and now I know another way to represent sizes

If you know 4-40, then then you should know that 5 is the next larger diameter of the numbered threads. A number one thread is .060 inches in diameter. Each number up from that is .013 inches larger in diameter. Way back the numbered sizes were used up to a number 14, but 12 and 14 are mostly obsolete. The number after the dash is the number of threads per inch. Larger sizes were specified by inch measurements such as 1/2-13 being 1/2 inch diameter and 13 threads per inch. Nominally a 10-28, 10-32, and 10-120 would all be the same diameter but with different pitch threads. There are set standard pitches for threads in National Coarse, National Fine, and National Extra Fine series. Before the sizes were standardized circa WW2, manufacturers often used oddball diameters and pitches so you had to get replacements from them or have them machined by a lathe operator.

[Walter Laich]

If you know 4-40, then then you should know that 5 is the next larger diameter of the numbered threads. A number one thread is .060 inches in diameter. Each number up from that is .013 inches larger in diameter. Way back the numbered sizes were used up to a number 14, but 12 and 14 are mostly obsolete. The number after the dash is the number of threads per inch. Larger sizes were specified by inch measurements such as 1/2-13 being 1/2 inch diameter and 13 threads per inch. Nominally a 10-28, 10-32, and 10-120 would all be the same diameter but with different pitch threads. There are set standard pitches for threads in National Coarse, National Fine, and National Extra Fine series. Before the sizes were standardized circa WW2, manufacturers often used oddball diameters and pitches so you had to get replacements from them or have them machined by a lathe operator.

guess what threw me is I had not heard of a 5-40 before. and since I know 4-40s are written like this and they wrote it 5/40 I didn't snap to the fact of what it was.

in any event it's a-coming and that's all that matters