Keith Type Bullet Dimensions

[wcwhitey]

https://rimrockbullets.com/xcart/-44-260-gr-keith-swc-fb-per-500.html

Hey all. I finally ran out of my Lyman 429421 cast bullet stash of many years. Being a fan of RimRock Bullets I ordered up some of these. As usual the quality is outstanding. They are advertised as a Keith Bullet. A quick look would tell you that the base is much longer than the 429421 (250 Grains). I measured the base to crimp grove on the 429421 at .32 and that of the Rimrock 260 at .36. It is .04 longer from base to crimp.

I emailed RimRock and asked "what mold does this bullet most closely resemble for reloading data purposes". The response was "This is our version of the original Keith Style SWC" so use any starting load data and work up from there". Duuh!

I don't have a Lyman 250-K on hand to measure but it looks closest to that, neither have I been able to find a schematic with measurements. Does anyone care to take a minute and check to see if this measurement of .36 is correct for my assumptions of the 250-K or does it resemble another bullet your aware of.

I have worked up some .44 Special target loads with this bullet already and it is obvious that it doesn't need as much powder as the 429421. 6.0 grains of Unique is a decent shooter, 6.5 even better but you can tell its getting up there. I want to develop some .44 Mag loads where specific data will be necessary.

Thanks in advance!

 

[GeoDudeFlorida]

https://rimrockbullets.com/xcart/-44-260-gr-keith-swc-fb-per-500.html

Hey all. I finally ran out of my Lyman 429421 cast bullet stash of many years. Being a fan of RimRock Bullets I ordered up some of these. As usual the quality is outstanding. They are advertised as a Keith Bullet. A quick look would tell you that the base is much longer than the 429421 (250 Grains). I measured the base to crimp grove on the 429421 at .32 and that of the Rimrock 260 at .36. It is .04 longer from base to crimp.

I emailed RimRock and asked "what mold does this bullet most closely resemble for reloading data purposes". The response was "This is our version of the original Keith Style SWC" so use any starting load data and work up from there". Duuh!

I don't have a Lyman 250-K on hand to measure but it looks closest to that, neither have I been able to find a schematic with measurements. Does anyone care to take a minute and check to see if this measurement of .36 is correct for my assumptions of the 250-K or does it resemble another bullet your aware of.

I have worked up some .44 Special target loads with this bullet already and it is obvious that it doesn't need as much powder as the 429421. 6.0 grains of Unique is a decent shooter, 6.5 even better but you can tell its getting up there. I want to develop some .44 Mag loads where specific data will be necessary.

Thanks in advance!

Quite possibly closer to the Hensley & Gibbs 503 than the Lyman 429431 or 429421.

 

[edwardware]

Unless you're talking to an extreme enthusiast (like a small-shop mold maker, or a CadtBoolits regular), "Keith" is any truncated cone semi-wadcutter with a lube groove. There's only a few people left who know or care closer than that.

 

[wcwhitey]

Unless you're talking to an extreme enthusiast (like a small-shop mold maker, or a CadtBoolits regular), "Keith" is any truncated cone semi-wadcutter with a lube groove. There's only a few people left who know or care closer than that.

I guess I am one of those. It’s not a big deal when you are just throwing lead downrange. I try to find the fine line between overthinking things and getting them right. Every once in a while I get it right!

 

[GeoDudeFlorida]

I guess I am one of those. It’s not a big deal when you are just throwing lead downrange. I try to find the fine line between overthinking things and getting them right. Every once in a while I get it right!

It actually makes a big difference. The H&G seats deeper than the Lyman 429421 - higher pressure for identical powder chargers - so they are different loads.

 

[wcwhitey]

It actually makes a big difference. The H&G seats deeper than the Lyman 429421 - higher pressure for identical powder chargers - so they are different loads.

I started with some math. Reduced the 429421 load data by .89 to make up for the case capacity difference with the Unique. Not perfect but it puts the 6.0 load in standard pressure Special range and the 6.5 in the Skeeter range. Seems to be about right, no worry about being excessive. .44 Mag will be another story even at the old 10 Grain level. Unique for me loses accuracy quick at the top end. If I cannot find specific data I will start at the 8 grain level and work up. Would love to get a 1050 to 1100 fps field load that shoots like the Classic 10 Grain 429421 load. But more than likely it will be accuracy over velocity that ends the exploration.

 

[GeoDudeFlorida]

I started with some math. Reduced the 429421 load data by .89 to make up for the case capacity difference with the Unique. Not perfect but it puts the 6.0 load in standard pressure Special range and the 6.5 in the Skeeter range. Seems to be about right, no worry about being excessive. .44 Mag will be another story even at the old 10 Grain level. Unique for me loses accuracy quick at the top end. If I cannot find specific data I will start at the 8 grain level and work up. Would love to get a 1050 to 1100 fps field load that shoots like the Classic 10 Grain 429421 load. But more than likely it will be accuracy over velocity that ends the exploration.

I buy that bullet from Stateline Bullets in Pennsy. They state clearly it's the H&G 503. But, I use IMR 4227 and a pretty stiff load based on older Ideal data. I forget the exact velocity out of my 7.5" RSBH but it's pushing the limits of my arthritis lately. Last time I loaded up I backed it down a few grains just to keep my fingers from aching. Yup, gettin' old sux but it beats the alternative.

The classic "Skeeter load" is 10gr. of Unique for a 6" bbl to get 1100fps (+/-) and 7.5gr for light target work at more modest fps - and recoil. Castboolits prolly has about 100GB worth of posts on the subject.

I switched from Unique to 2400 to IMR 4227 to No.4100 a few times and back but always end up using either 2400 or IMR 4227. 4100 and No.9 just don't "do it" for me in the heavier loads. Now, if we were talking a 200gr. BNWC, that would be different.

 

[black mamba]

I ran your load through Gordon's Reloading Tool and with Unique @ 6.5 grains, the .04" deeper seating increased the pressure from 12.5 kpsi to 13.5 kpsi, and the velocity went up 20 fps. The same increases are equal to the shallower (.32") seating with 0.25 grains more powder.

 

[wcwhitey]

I ran your load through Gordon's Reloading Tool and with Unique @ 6.5 grains, the .04" deeper seating increased the pressure from 12.5 kpsi to 13.5 kpsi, and the velocity went up 20 fps. The same increases are equal to the shallower (.32") seating with 0.25 grains more powder.

Thank You! My math isn’t too bad then. I am probably going to work from 8.5 grains or so in Magnum cases using the same thinking. I don’t chronograph my loads but once in a while. I find what I think puts me in the ballpark and then go with the most accurate rung in the ladder. Then when I can get my buddy to drag his chronograph out and check my work. Maybe once or twice a year.

 

[41 Mag]

So ya got me thinking and rummaging around on this a bit. I pulled out one of my HG bullets and best as I can eyeball the measurements mirror the drawing posted above.

It's been a few years back but there were also group buys on Castboolits.com for true to design Keith bullets. There were a couple of folks who produced the 358, the 410, and the 429 versions of the Keith SWC that were used to make the molds.

I completely understand the added depth of the bullets being an issue but if they shoot well I could easily work around the shorter powder charge.

 

[Bazoo]

I have an RCBS 44-250-K. It measures .350 from the base to the crimp groove. Mine weighs 265 grains from my 50:50 WW: Pb+Sn alloy.