I have recently acquired a 325B .30-30 and need some info about the rear sight. It is not the Dockendorff dial-type rear sight, but the notched twin-ramp variant. Does anyone know what increments these were graduated in, and, if so, at what range they start?

Incidentally, I would also like to know, if possible, when, in the 1947-50 life cycle of the 325, was the "B" produced? Mine either has no serial number or it is so well hidden that neither I nor my dealer could find it, so dating it that way is a non-starter.

Any help is appreciated.

Afraid you are on your own regarding the rear sight's graduations, as they are a trial and error sort of thing.
Would suggest shooting it at its lowest setting at a moderate distance and go from there. These guns were not serial numbered
(S/N's were not required until pasaage of GCA 68), but there may be a barrel code in an oval. One of the knowledgeable folks here should be able to interpret it for you. I had a 325 a long time ago, but never bothered to pay much attention to it. Never figured them to be a possible sleeper...

If it was made in 1949 or later, it should have a small oval ring with numbers and a letter inside it. Small, maybe 3/8" long, probably very faint, and located I-don't-know-where on a 340/325. It is a combination inspection/date code, the letter of which will tell what year it was made. Look for it and report back, and we can tell you it's birth date (or close). (A=1949, B=1950, etc. They skipped some letters, but not 'til long after when you think it was made.) Pre-1949, you're SOL.

There is a circle with a "B" inside it, but no numbers, and what appears to be a proof mark. Both are on the barrel just ahead of the action and behind the rear sight.

The brand name of the rear sight is "Marbles, Gladstone, MI, USA." I did shoot it at the lowest elevation and it hits about 8 inches high at 100 yards with 170 grain SPs, and about 4 inches high with 150 grainers. I plan to try 130s and see if I can get the thing to hit near POA.

"B" = 1950 ("A"=1949)

Possible remedies:
- Remove the elevator completely?
- Reduce height of notch in rear sight leaf?
- Put a taller front sight into the front sight ramp dovetail?
- Given lighter bullets hitting lower than heavier, is it possible that you are just getting a pattern instead of groups? (Are you shooting 3 or more rounds to determine where bullets are grouping?) Maybe barrel is dirty or pitted?

I seem to remember some Marbles rear sights having an adjustable rear sight blade (sliding, with retainer screws).

It groups consistently high with the given bullet weights. I shot full 3-round mags and had a spotter. It shoots straight as an arrow down the pipe, elevation seems to be the issue. I don't want to alter the weapon in any permanent way, so reducing the notch height or changing the front are not options.

The rear sight does, indeed, have a sliding adjuster, but it is already set as low as it appears to go.

I understand original. However, factory org sight was not Marbles, likely too high 4 front sight. This ain't fun w/ iPhone...

Also try 125 gr. bullets; should drop your groups and OK for anything thru deer at decent open sight ranges.

In agreement with changing out the rear sight. It's not factory, so why not? If keeping it in it's current form is important for some reason, swap the sight out and put it in a drawer for posterity.

Adopting light bullets may lower the group, but will drastically limit your flexibility.

Spend the couple of bucks it'll take and replace the sight. 'Taint rocket science!