I just aquired a .218 Mashburn Bee on a Martini-Cadet action. Mounted up an old scope and went to the range. Finally got the scope adjusted (holes offset to the left!) and with Win Factory .218 Bee ammo, 46gr bullet, the best group I could get is 5/8" at 50 yds.
I know nothing about Bees, Mashburn or otherwise. Question, if I reload the Mashburn case, can I expect to get better accuracy?
5/8" at 50 does not seem very good to me for what the cartridge is designed for.... It does shoot nice 3 shot cloverleaf groups, though.
The bbl is a Remington RF takeoff, apparently, and -appears- to be in good shape, as far as the bore is concerned.
Although leaving a lot to be desired cosmetically, the mechanicals seem to be well done.
Thanks for your response.....

The Bee was never known to be a "tack driver". It can shoot quite well in certain rifles. I have a #1 in 218 that shoots right @ 1'' (+/-), a buddies Model 43 does 1 1/2 (+/-).
Will the Mashburn loaded rounds be more accurate? Hard to tell and only one way to find out, find a set of Mashburn dies and load your fireformed brass. IIRC, there is more than one version of the Mashburn Bee wildcat. I'd make a chamber cast before investing in the dies.

For a martini cadet action with a Rem barrel that is excellent accuracy. My .218 Bee No.1S also shoots 1" groups at 100 yards for five rounds.

All you get with the Mashburn case is larger case capacity for a wider choice of powders. The .218 Bee case will run compressed loads with most rifle powders.

The old discontinued powder WW680 was THE powder for the .218 and I now have to run 296. The Mashburn will increase the number of powders that will fit.

Well, a rimfire barrel will usually have much shallower lands and a slightly smaller bore than a centerfire barrel, so you can't expect benchrest accuracy from it.

Certainly careful handloading should be able to improve over factory loads (as this is true with most any rifle.) Try a variety of bullets, but keep them fairly low weight (45 grains and under) to give the slow twist of the rimfire barrel a better chance to stabilize them. You might try some .223" bullets made for the Hornet while you're at it.

I haven't loaded for the Bee, Mashburn or otherwise, but if Code4 says that Winchester 680 was a great powder for it, then you can still find the same spec powder in AA1680. AA1680 does great things for me in both .22 Hornet and .221 Fireball. Since those cartridges bracket the .218 Bee/Mashburn in capacity I would think that AA-1680 would do well for you.

I've owned two different Mashburn Bees on Cadet actions, one in .20 caliber and the other a .218. If you're using a rimfire barrel, the twist may be pretty slow and the bore tight. I'd try the 35 grain .223 diameter bullets designed for the .22 Hornet and see if that improves your group sizes.

FWIW, the .20 Mashburn would do about 0.7" for 5 shots at 100 with the best loads. I'm still working on load development for the .218 Mashburn, which is a relatively recent acquisition. To date, it has not performed as well as the standard .218 Bee I have which is also on a Cadet action.

More discussion:
Careful measurment of the fired case confirms it's the Mashburn version -at least it agrees with the specs for that cartridge in the "Handbook of Cartridge Conversions".
I do have some Bee rounds loaded with a Berger 40 grain bullet, which I did not shoot. They might shoot a bit better. So, the plan is another trip to the range, shooting at least most of the remaining ammo at 100yds, to get cases formed, and compare the two different loadings, and an accuracy check. (Been using a Caldwell Lead Sled for this, it sure does make it easier-especially for my old eyes)
I ordered a neck sizer and seater die from RCBS. Did not want to invest yet in a full Mashbern die set, as the rifle may get rebarreled (thinking hard on 30-20).
Don't have any AA-1680, but do have some IMR 4198. But I think the only 22 bullets I have are 55grns, left over from a 22-250 project, so maybe I can pick some up with some lighter bullets.
One small problem is a lack of Mashburn loading data. Of course, easy enough to start at Bee levels and work up, but it would be nice to have some comparisons.
Later,

From Ackley's book:

16.5 - 17.3 grs 4198 with 55 gr bullet, 3005 - 3316 fps.

Best powders in my std Bee are H110 and R-7.

I have R-7, in fact, that's what I use in my .17 Ackley Bee.