Theoretical Load Question: Bullet Weight & Bullet Seating Depth

[Scooter1942]

Hi all. I've been lurking for a bit, but this is my first post...I hope this is the right forum for this question. Be gentle!

Curious to know what your thought would be on this question.

I recently developed a load for my S&W 1854 lever gun in 44 Magnum. It spits a Rim Rock 255 gr (260 actual) Keith SWK-G/C bullet at 1720 fps from a 19" barrel. Bullet sits atop 23 gr. H110 with WLP primers. The load was holding multiple 5 shot 1" groups at 50 yards from my rifle with open sights. Extreme spread was 25 and Std. Deviation was 10.4. This is a pretty hot load but doesn't quite max out based on load data I've found on LoadData.com.

Recently I received some 280 gr (279gr actual) Montana Bullet Co. WFN-GC bullets. Given that they are 20gr heavier, my initial plan was to back down to about 21-22gr H110. But upon closer inspection, I also recognized that these bullets are shorter behind the crimp groove than the RimRock 255's, which then effectively decreases seating depth. I also have to consider that H110 likes a full case of powder and very little air space for maximum consistency and minimum deviation. Reducing the charge would be working against me in this regard.

So, that left me to wonder, should I keep my load at 23 gr given the bullet isn't seated as deeply, or back it down? In other words, how much consideration should I give to bullet depth vs. bullet weight when building up a load? My goal would be to get this 280 gr slug above 1600fps and to maintain the accuracy I achieved with the Rim Rock bullet.

Thoughts?

[waksupi]

I would start at the lowest recommended charge, and work up. You are developing an entirely new load.

[Kraschenbirn]

If your boolit isn't seated as deeply, then your OAL is going to be greater. First thing I'd do would be to make up a dummy round using the Montana Bullet and make sure it cycles through my rifle. Once upon a time, I went through something similar with an early "JM" Marlin 1894...very, very touchy on OAL. Fortunately, I'd only put together a 20-round 'trial run' for load testing so pulling the boolits and reseating wasn't too much of a PITA.

Otherwise, I'm with Waksupi...back down to the recommended "start load" for the 280 grainer and work up from there.

Bill

[Der Gebirgsjager]

Welcome to the Castboolits Forum, Scooter1942. Glad to have you aboard.

DG

[gwpercle]

#1 Since the boolit is shorter behind the crimp groove ... and heavier , the first thing I would do is seat a boolit to the crimp groove in a dummy round or two and check if the dummy rounds will feed from magazine into the action and then cleanly extract without leaving the boolit stuck in the throat ...

No sense working up Theoretical Loads if the oal will not function in the rifle !
Been there , Done that !
Gary

[Barry54]

Welcome to the forum!

Excellent question for a first post! I feel like I read somewhere that H110 loads get a 3% reduction from maximum and most other powder calls for a ten percent reduction from maximum.

I myself will be following this thread to see responses from others.

[Scooter1942]

Bill & Gary,

Yep...that's the very first thing I did. These 280's cycle fine when seated to the crimp groove. They have a very slight taper at the nose and smaller meplat than the 260's I loaded. Live and learn...Last week I loaded up 20 rounds of 260 gr. WFN-GC from Montana Bullet Works and they would NOT feed in my lever gun. So, I assumed I might have the same issue with the 280's, but I was surprised to learn that they cycle just fine at 1.640 OAL, which happens to be right at the crimp groove.

[Delkal]

Different bullet shapes can give very different OAL's so for loading an unknown bullet with another published data the printed OAL is little more than a recommendation (think a flat nose bullet vs round nose vs a spitzer). To determine max OAL of a cartridge in the chamber I take a sized case and cut two slots in it with a dremil by the mouth. This makes it so a bullet can be pushed in with only a slight effort using your fingers. I seat the bullet long in the case, blacken the bullet with a dry erase marker, then gently chamber and gently take it out. The bullet will be seated by the lands and that is your max OAL for any unknown bullet. The dry erase marker is because sometimes a cast bullet will stick and pull out some when you take it out. With the dry erase markings this will be obvious and you push the bullet down with your calipers till the lines match up and get your reading.

I seat most bullets 0.025 off the lands but more is OK. You have to make sure they fit in the magazine and cycle.

[Bazoo]

Howdy and welcome scooter1942! First off, have you looked for data specific to the LBT bullet? I'd expect there to be data specific to that since LBT bullets are quite popular. You could probably find someone that loads it over on singleaction.proboard forum, if you don't here.

I'd be comfortable with your suggested workup plan, and I'd expect the max charge for the LBT would be similar to (maybe more) the Rim Rock Keith, given the differences.

Regarding your gun; did you get the standard version or the fancy version with wood stock?

[Bass Ackward]

For 17 years, I used 20.5 grains H110 / 296 with that slug. Got another gun and had to kick it up to 21.5 grains. But as others have stated, you change a single component and you ALWAYS start low & work up. That’s the reloaders creed.

[Scooter1942]

Howdy and welcome scooter1942! First off, have you looked for data specific to the LBT bullet? I'd expect there to be data specific to that since LBT bullets are quite popular. You could probably find someone that loads it over on singleaction.proboard forum, if you don't here.

I'd be comfortable with your suggested workup plan, and I'd expect the max charge for the LBT would be similar to (maybe more) the Rim Rock Keith, given the differences.

Regarding your gun; did you get the standard version or the fancy version with wood stock?

I bought the standard version. I have the new Ruger made Marlin's in 44 and 357, but wanted something a little more "all weather" for this gun. Slapped a Aimpoint T1 on the rail and love it.

[Bazoo]

Cool. I think you're the first person that I've seen that says they have one.

[gwpercle]

Bill & Gary,

Yep...that's the very first thing I did. These 280's cycle fine when seated to the crimp groove. They have a very slight taper at the nose and smaller meplat than the 260's I loaded. Live and learn...Last week I loaded up 20 rounds of 260 gr. WFN-GC from Montana Bullet Works and they would NOT feed in my lever gun. So, I assumed I might have the same issue with the 280's, but I was surprised to learn that they cycle just fine at 1.640 OAL, which happens to be right at the crimp groove.

Awesome !
Gary

[Scooter1942]

Quick update.

Last night I loaded up 20 rounds of the 280's. Did half with 21 gr and the other half with 22 gr of H110. Given that I found a load with a 325 gr bullet with 22 gr. I think I've left plenty of margin. Hopefully I can get out this weekend to see what kind of velocity and accuracy I'm getting.

[fredj338]

Bullets are rarely plug & play. Change to a diff one, you should back off & work up. At max, everything matters.

[Sandspider500]

What does that rimrock 255 measure? On rimrocks website it says it's .812, and has a nose to crimp of .373, is that correct? If you're using the 429244 or 429421 as a reference, those have a pretty long nose. By that I mean there's more bullet outside the case that inside. You may want to check out this site, it's pretty neat, and valuable tool in my opinion.

https://bulletmatch.com/bullets?bmsc...er_page=20&s=0

[Scooter1942]

Hi all. Thought I'd follow up with my last loads.

Yesterday I headed to the range with the same S&W 1854 and three loads.

First, I had the RimRock 255's SWC-Keith with GC under 23gr of H110 as before. I had about 10 rounds from the last loading session. Then I loaded up about 15rds each of the Montana Bullet Works 280 WFN-GC with 21 gr. and 22 gr. of H110

Sadly, the test was a bit of a flop because the top rail on the S&W 1854 had not been properly tightened and it loosened up over the shooting session, so accuracy testing was a no-go. But, I did gather some ballistic data gathered with my LabRadar.

RimRock 255 gr. SWC-K-GC. This one surprised me because these 10 rounds were nothing like the data I collected before, even though they were from the exact same loading session.
23 gr. H110
Win Cases
WLP primers
1.666 OAL
1541 fps avg
201 fps E.S.
68.2 fps Std. Dev.

Montana Bullet Works 280 gr. WFN-GC
21 gr. H110
Win Cases
WLP Primers
1.649 OAL
1575 fps avg.
129 fps E.S.
52.6 fps Std. Dev.

Montana Bullet Works 280 gr. WFN-GC
22 gr. H110
Win Cases
WLP Primers
1.649 OAL
1636 fps avg.
62 fps E.S.
24.5 fps Std. Dev.


No cases showed signs of pressure. But, I'm a bit disappointed with my extreme spread and standard deviation. Both of my previous loads with H110 and 2400 had standard deviation in the single digits. Those were 23 gr. of H110 and 19 gr of 2400 with the 255 gr. slugs. Interestingly, my 2400 load which I put on the back burner because it was considerably slower (1565 fps) than my 23 gr H110 load (1720 fps), actually tested a little faster than my H110 load this time. I may have to revisit that 2400 load.


Anyway...I'd appreciate any musings ya'll might have. I think my next steps are to:
1. Try H110 .5 gr. lower and .5 higher than my last try. So, 20.5 gr. and 22.5 gr. with the 280 gr bullet to see if it positively impacts velocity spread.
2. Load up some 2400 with the 280's to see if I can get a low std. dev., 1600 fps, and reasonable accuracy.