Any Special Considerations When Loading Oversized Cast Bullets?

[SingleSeven]

I recently purchased some 430gn Oregon Trail and 405gn Cast Performance GC bullets to load for my .45-70 Marlin 1895. I ordered them both in the oversized .459 option (although the Oregon Trails mic around .461-.462 according to my Starrett caliper and the Cast Performance are about .460). My question is do I need to do anything special for these bullets that I wouldn't have to do when reloading .458 diameter slugs? For example, virtually all of the reloading data I have seen are for .458 diameter bullets so is it recommended that I reduce charges below the starting point an additional percentage beyond the recommended 10% reduction when working up a new load? Should I use a wider plug when expanding the cases to accommodate the wider bullet? I own the RCBS cowboy die set. Any other considerations or recommendations? Thanks.

[4719dave]

Did you ever slug your barrel ide start there ..

[5Shot]

Just start 10% below max and work down or up from there, but if they don't chamber or chamber really hard, there is likely to be some difficulty. Slugging the barrel is the only way to know what you need for your gun, as 4719dave mentioned already.

[Yodogsandman]

If those boolits will fit into a case that's been fired from your rifle, they should be fine. Be sure that the loaded round will fit in your chamber without forcing it in. The RCBS cowboy dies will expand the case neck for cast boolits. Start with listed starting loads and work up carefully, as usual.

[SingleSeven]

I slugged it at .4569 at the widest part of the fish weight. On a side note, when I made a dummy round for the Oregon Trail bullet I discovered that the gas check was about a mil less in diameter than the bullet. I had belled the mouth of the case based on the gas check, but when I seated the bullet there was considerable lead shaving. I mic'd a few of the other Oregon Trail bullets and sure enough the gas checks were all smaller than the bullet width by about .001 on average. I guess I can understand the logic that having a thinner gas check ensures better case wall tension on the bullet, but I just wish I had known that before belling the case mouth so I could have belled using the bullet upside down. This wasn't the case with the Cast Performance bullet, which had the gas check near exactly the same as the bullet diameter.Thanks everyone for the advice. I will proceed loading with the tools and material I have.Yodogsandman, my wife's an adorable deplorable who votes (and she has the t-shirt to prove it).

[5Shot]

.4569 or .4596?

[SingleSeven]

.4569. I slugged it twice because I thought it was undersized too, but after speaking with Remlin they assured me it was within spec for the rifle. With that said the rifle shoots factory jacketed .458 ammo reasonably well.

[5Shot]

How come you ordered the slugs so oversized then?

[SingleSeven]

I ordered them at .459, which is about 0.002 larger then the barrel diameter of .457. I didn't expect them to measure in at .460-.462. Do you think this is going to be problematic?

[Strtspdlx]

I would imagine it will cause pressure issues depending on where the bullet engages the rifling and how far out of the case it is when it does so. I would consider buyin a Lee push through sizing die if available in .457-.458. Did you slug the barrel from breach to muzzle or vice versa? Also have you checked the accuracy of your micrometer? I have a set of precision ground blocks I can use to check and zero my mics if needed. If not measure a jacketed bullet of a known good size and compare to your mic.

[SingleSeven]

I haven't had the micrometer calibrated since I bought it new, but it agrees well with the 3 year old starrett caliper and the plastic rcbs caliper that I bought some 30 years ago when I first started reloading so I'm confident the measurements are accurate without actually having a known reference diameter to compare to. Probably not a bad idea investing in a precision reference though. I slugged from muzzle to breech both times. I've read that the cast bullet should be 0.002-0.003 oversized ideally. Of course that might have been written by an isis operative trying to get me to kill myself with my own gun;-) Joking aside, I was under the impression an oversized cast projectile would be swaged into the correct diameter after the first inch or so of barrel travel ensuring a near perfect seal while minimizing any pressure spikes. It seemed logical as I read it, but I don't have actual experience, which is why I'm asking all these dumb questions today. Thanks for your help.

[Yodogsandman]

Your impressions are correct. Nice to know what the barrel slugs at but, the critical measurement is the chamber throat just ahead of the case mouth and before the rifling starts. Boolits should be sized .001" under that measurement. This assures that the boolit starts out straight and is fired straight into the bore with no room to get cocked out of alignment. The boolit will be swaged to barrel groove size when fired, making a perfect fit. Boolit metal seems hard but is really like gum when exposed to pressure when fired.

Here's a good thread on making slugs....

http://castboolits.gunloads.com/showthread.php?218414-FYI-This-is-how-I-do-a-pound-cast

[runfiverun]

your fine.

[MostlyLeverGuns]

Long ago P O Ackley determined that long before maximum pressure was reached, the bullet was sized into the rifling. He used 8mm and .35 bullets in a 30-06 with the neck enlarged so they would chamber and did not find extreme pressure problems with similar weight bullets. A couple thousandths with a lead bullet is not much. Expanding your case necks to accept the large bullet without damage would be my concern. Many Palma barrels are bored very tight to enhance accuracy with ammunition issued by the match sponser.

[FredBuddy]

I'm no expert, but this is what I have tried with good results:

As Yodog says, I took a fired case and found it will accept a 462/463 powder coated boolit with very little effort. A dummy round chambered nicely in my JM marlin 1895. I loaded some up, no signs of high pressure, quite accurate, but I noticed the barrel was a little warmer than usual compared to the same boolit at 460.

I was trying to avoid resizing what has been scarce brass.

Next, I'll try to minimally resize brass till the 460's fit like the others did. My goal is to avoid overworking the brass and avoid the bulge of fully resized brass.

Like the OP, I use RCBS cowboy dies, and I also have a bigger NOE expander plug.

All of this to say "keep on keepin' on".

[country gent]

Check you expander plug for its size I've ssen 45 cal rifle expanders for jacketed bullets as small as .454 dia. This size expander will cause the case tio size the bullet down in dia. You may want to find an expander for your die at ,458-.459 dia for these bullets. Another thing to check is fit of seating stem to nose of the bullet, you want a good fit that doesnt distort the bullets nose when seating. As to powder charge Decide on the velocity range you want to shoot these bullets and find the data for the powder you want to shoot. Start low and slowly work up chronographing as you go if you have one. Watch the extreme spreads and or standard deviation numbers along with the groups. When a load becomes more effient and into the correct range the ES and SD numbers go down and accuracy ussually tightens up as they do. MAke sure cases loaded rounds chamber easily. Check sized cases before loading its way easier than pulling bullets. Check case mouths for size, If you can get away only partially sizing it makes brass life much longer than full sizing and expanding necks back up .003-.005" everytime. Annealing case necks may also help with loads. On new brass lightly trim to length to be sure case mouths are square and all cases are the same length. This makes crimping much easier and consistant. Load some test loads, fire for accuracy and velocity and go from there, find what your rifle wants and likes.

[dubber123]

your fine.

I agree. I shoot .462" boolits in my 1895 for a reason, even though much over bore size, they help center the boolit in the gigantic chamber, and they shoot better. Follow the others suggestions for checking chambering issues, but I would not sweat the oversize part. I shot .006" overbore boolits in a 50-70 Contender pistol I have, and noticed no changes from a much smaller boolit. Lead is pretty soft :)

[rhouser]

Shoot the .460 and don't look back. If you have any extra money, buy a set of rcbs cowboy dies. They are set up for the cast lead. My marlins LOVE fat boolits. The micro-grooves demand them, the ballard cut rifles love them. Ranch Dog molds were the pioneers in cast lead accuracy for Marlin rifles. All Michaels 45-70 molds dropped at .460+ My lee push through sizer is .460 for 45-70. I have 3 rifles and 5 molds. 2 rifles are Marlins and 1 is a Win High Wall.
rch

thanks rch

[Wayne Smith]

The OP has the RCBS Cowboy die set. Load and shoot, as R5R said, you are fine.

[mnewcomb59]

Any Special Considerations When Loading Oversized Cast Bullets?

Pull one after seating and make sure it is still oversized..

[SingleSeven]

Thanks all. I've loaded up 50 rounds for each bullet and will test at the range in the near future. I manually cycled several rounds of each bullet type and they all went in and out of the 1895 just fine. I'm still going to be a little trepidatious about pulling the trigger for the first time though. Maybe I'll invite my boss to tag along and give him the honor of first discharge;-)