Commercial cast plain base in milspec barrels

Going thru my stuff I've found a few boxes of 30 cal plain base 165 grain heads. Bands measure .309 to .310, the nose is under size at .297. Most are bevel base but I've some flatbase also. I've a 2 groove A3 I want to use them in. The nose falls into the barrel as expected but the band diameter is about 1.5 cals long.

Being of a moderately hard alloy as commercial cast tend to be what can be used for loads that may work for 40-50 rounds of firing? I've overcoated them with 50/50 LLA and mineral spirits hoping that may help to a degree.

Not fixed on a velocity window, just whatever may hold up ok for the 40 round match.

What are your past experiences on something like this?

I will be posting results good or bad when we get some downrange.

I’d try 5-6 grs of bullseye with those and see if they will shoot with that undersized nose . It’s a low power load but will still shoot 10’s at 50 yds with a bullet it likes . I’ve shot many many of the lee 155 without the check with that load and would hold pretty darn good out to 100 yds when I used to shoot reduced high power matches with my 03A3

Try 9 grains of blue dot, 7 of red dot 8 of unique if you have those powders of course.
The 03a3 is one accurate puppy!

The above loads should work fine for you. I shoot plain based 309 bullets in my 30 cal military rifles, and 313 plain based in my Enfield and 1909 Argentine Mauser. With my military rifles I found great accuracy until I started trying to push up in the 1400-1500 fps range. As long as I stayed lower plain base was fine with good accuracy and no leading. 1000 to 1200 fps or so was particularly good and accurate. Fundamentally, there is nothing wrong with shooting plain based lubed bullets-- they just can't be pushed to as high a velocity as you can with gas checks.

Rule of thumb in my neighborhood for plain base is about 1400 fps. max.

Thanks for the replies. I'm loading some for a range trip this week. My main concern was 'harder' commercial vs softer that I can cast. I'll try the commercial but save some for a run off against some home cast. I've some 22 backstop material that should work for this.

The 2-groove barrels are generally very good with bore- riding designs when they fit. You might be able to seat them out far enough that the front driving band is supported in the throat. Lacking that, they're unsupported out front and fail to start straight and centered. I had a two-diameter H&I die made so I could properly size the nose of a mold that cast too big, but it works just as well to bump up noses to land diameter that are a bit small. Previously, I had some success using a standard die. If you have a Lyman or RCBS lubrisizer, you might try setting the stop screw waaay down and runnimg the boolit into the die until the top punch hits the top of the sizing die. While holding the lever down, turn the stop screw back up until it stops against the ejector pin. Bring the lever up and turn the stop screw up another eigth of a turn or so. Bring the lever down until the boolit bottoms out and bump down on the handle until the top punch contacts the top of the die again. This will shorten the boolit just a bit and fatten the bore-riding nose. If it's still too small, turn the stop screw up a touch more and do it again. Once the nose is a friction fit in the bore, you're set to do the rest of them to the same dimensions.

Don't be too rough on the lever, because some of the linkage parts on this type of lubrisize are fine for sizing, but they aren't terribly strong.