Questions about CRIMPING .45/70


March 31, 2010, 08:09 AM
I am new to reloading....I plan to reload for a Marlin 1895 Cowboy rifle. Another member suggeted that if I use plain lead bullets I should use the "cowboy" die set and a "seater plug" because the die alone will not seat a round or flat nose bullet correctly. Where do I find a "seater plug"....I have been on RCBS website and cant find anything. Also he stated that when firing ammo in a Marlin a heavy crimp is needed. I am going to be reloading mostly plain lead bullets, but I am unsure of the size yet....maybe 405 gr or 525 gr beartooth. What kind of die wil give me the crimp I need? Should the crimp be done at a seperate stage on the press or will a RCBS press do it while seatng the bullet? Any info will be appreciated. Thanks in advance.

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March 31, 2010, 10:20 AM
The seater plug comes with the dies (cowboy and regular)...but RCBS only has a 1 seater plug with their 45-70 is for round nose bullets. The seater plug for flat nose bullets from 45acp pistol dies can be used in its place. Call RCBS...they'll know what you need when you say seater plug for flat nose 45-70 bullets...or just ask for one for 45acp flat nose bullets.

Crimp...there are 2 reasons for a good crimp in Marlin rifles. 1 is to keep the bullets from getting pushed deeper into the case during recoil. 2 is my experience with the 45-70, it likes to be crimped good.

I crimp cast bullets that have a crimp groove with RCBS a separate operation, not while seating the bullet (its more consistent that way, and doesn't damage the bullet).

For crimping bullets like the Remington 405 (no crimp groove) or similar...the Lee factory crimp die is a must have. Some bullets that can be used in the 45-70 have a crimp groove, but its in the wrong place...the Lee factory crimp die will make its own crimp groove in the bullet as it crimps.

March 31, 2010, 11:03 AM can use the round nose seater plug with flat nose bullets. But its not the ideal it may booger up the edges of the meplat on flat nose bullets, which won't do accuracy any favors.

The cowboy dies may have a different seater plug...but the plain RCBS 45-70 dies, only have the one for round nose bullets.

March 31, 2010, 11:20 AM
Thanks for the clarification....I have found a place here in Canada that makes cast bullets

They make a 450 gr cast is a round nose flat point with 4 lubricating grooves and a beveled measures .459 in diameter which is what you recommended to me last night....would you have a look at the wesite and let e know your opinion on this bullet....I can get these REALLY

March 31, 2010, 11:21 AM
When you get to the site click "price list" on the left to see the bullet selection

March 31, 2010, 11:28 AM
I'd get the 420 grain 45-70 RNFP GC TLG if it were'll need that gas check in my opinion.

March 31, 2010, 11:29 AM
What is the purpose of the gas check, just seals the bullet better?

March 31, 2010, 11:33 AM
Protects the bullet base from gas cutting when running high pressure/velovity loads.
Also helps to prevent heavy bore leading by sort of scraping out the previous shots lead the next shot.


March 31, 2010, 11:34 AM
Yes...and it also serves to clean some of the lead out of the barrel with each shot.

If you are gonna load that 45-70 to its potential with those bullets (appx. 1,850 fps), you'll need the gas checks.

March 31, 2010, 11:38 AM
ok thanks...all this is starting to make more sense now....thanks guys...when you looked at the site did they look like "decent" bullets....I noticed the 420's only have 3 lube grooves...also will i still need the lee crimper or will the RCBS set of 3 dies do the trick?

March 31, 2010, 11:46 AM
They look good to me...I didn't look to see if the hardness was listed on there. (Edit: the hardness is 25, thats plenty hard enough)

The 3 lube grooves will be fine...just be sure to check them before loading them...sometimes you get a bullet with grooves, but no lube. (usually one or two per box)

The RCBS dies will crimp those just fine....size and flare the brass, trim it to 2.095"...then seat the bullet until the top of the brass is even with the top of the crimp groove in the bullet (do this simply by looking at it). This is to ensure that brass is crimped into the entire groove...and not just barely crimped.

When the bullet is properly crimped...the brass should butt right up next to the lip on the bullet...the lip on the top of the crimp groove.

pic added for reference...

March 31, 2010, 11:50 AM
RCBS seating die will crimp it just fine.
The ring around the bullet with no grease in it is the roll crimp groove.

This bullet has no crimp groove so you would crimp over the shoulder of the front driving band. (For single-shot rifles with no magazine tube problem)


March 31, 2010, 11:57 AM
Ok sounds easy guys have been MORE than helpful...thanks a million...maybe seems like stupid questions but when you're a newbie all this is a lil overwhelming to take in at once.....I also bought "THE ABC's OF RELOADING" is a really good starter book. If I need ya again, I know where you

March 31, 2010, 12:01 PM
That ABC's of Reloading is worth every penny you paid for it and then some...

We are here...when/if you need us.

Just be safe...if you have doubts, ask first before proceeding because the only stupid question is the one not asked.

March 31, 2010, 04:50 PM
which kind of brass is best??...i have my choice between winchester and remington...thats all i seem to be able to get my hands on up here in Canada....

March 31, 2010, 06:35 PM
I prefer Remington...

David Wile
March 31, 2010, 06:36 PM
Hey Mullins,

I got a Marlin Cowboy back in May of 2001, and my first reloads were done on my RCBS Rockchucker using a real old RCBS 3-die set. I started with some commercially cast bullets, but they were not gas checked, and I did not like them. I bought two RCBS mould blocks: one a double cavity 300 gain gas checked bullet, and the other a single cavity gas checked bullet. Both bullet designs were exactly the same other than the lighter bullet was shortened enough to make a difference of 105 grains. I like my own cast bullets much better than commercially cast bullets, and I now make my own aluminum gas checks for the 45-70.

After arriving at some loads I liked using the single stage press, I decided to start reloading the 45-70 on my Hornady LNL, but I found my old RCBS dies were not long enough to easily adjust in the thicker LNL press. I bought a regular 3-die set of Hornady dies in 45-70, and they work just fine with the LNL press.

All my 45-70 cases are either Remington or Winchester, and I cannot tell any difference between them. When they were all empty at the same time, I sized them all, trimmed them all to the same length, and then chamfered all the case mouths. This process allowed me to set the seating and crimping die so that one operation with the third (seating & crimping die) would seat and crimp the finished round at the same spot on the bullet and without shaving any lead. If you have cases of different lengths, you will not be able to seat and crimp the bullet at the same place.

Also for your consideration, once you trim and chamfer your cases to the same length, you will probably not have to trim and chamfer for a very long time since straight walled cases like the 45-70 do not lengthen over use like happens with bottlenecked cases. I cannot see why you will not like the Remington and Winchester cases.

Best wishes,
Dave Wile

March 31, 2010, 06:50 PM
Thanks David, our advice is much appreciated. As much as I would like to cast my own bullets, I think I will wait until I am experienced in reloading before i attempt IS my goal though, eventually...I will probably go with the remington brass if it is just as good as the winchesters due to the fact it is a lil cheaper here.

March 31, 2010, 07:05 PM
Also, how do I know what I am going to need for primers? There are so many different brands and they all seem to have their own "numbers" which i'm guessing means for different applications....any advice?

March 31, 2010, 07:24 PM
i was thinking of using the CCI BR2 primer like ridgerunner recommeded....what is the difference between standard and benchrest??

March 31, 2010, 08:51 PM
The difference is consistency...the BR2's seem a tad hotter too, but either will work.

I use the BR2's because I have like 25,000 of them...for my 308's.

Remington brass is thicker...and like you say, a tad cheaper.

March 31, 2010, 11:33 PM
You can crimp with the seater die, or you can crimp separately.

I highly recommend the Lee collet-type FCD for crimping rifle and bottleneck pistol cartridges.


April 1, 2010, 06:34 AM
when you crimp with the seater die, does the press do this all in one action or do you have to lower the press handle twice?

April 1, 2010, 10:38 AM
You can set it up to do it either all at once or as a separate action. I like to crimp my 45/70 as a separate process to keep an eye on them specifically. I've roll crimped with a standard die as well as using a Lee Factory Crimp die. I like the Lee for the 45/70, it uses a collet to give a nice firm crimp by squeezing a small band of the case mouth inward rather than a step inside the die that rolls the edge of the brass over.

I like that 420g GC bullet up there for the 45/70, by the way. That could be loaded to be a real good all around load.

Good Luck!

David Wile
April 1, 2010, 10:39 AM
Hey Mullins81,

Yes, you can seat and crimp a bullet with one cycle of the press handle. This is true whether you are using a single stage press or a progressive press, so let's go through these steps with the assumption we are using my old single stage RCBS Rockchucker press. We will also assume we are loading fifty .357 Mag cases that are now sitting in a wood block already sized, reprimed, case mouth expanded and slightly belled (remember, any time you bell the mouth of a case, it should never be belled any more than necessary to just barely allow the bullet to slip slightly into the case mouth), and all the cases have been charged.

At this point you will now seat and crimp the bullet in one operation of the press handle. The trick to doing this is to adjust the seating/crimping die properly. So, you place a charged .357 case in the shellholder, raise the ram to its top. Now screw the seating/crimping die into the press until you first feel the die touch the case mouth (if you have difficulty in getting the belled case mouth into the seating/crimping die, you have way too much bell in the mouth, and this cannot be stressed too much).

When you feel the die touch the case mouth, back the die back out a half turn and turn the locking ring down hand tight on the top of the press. Also backe the bullet seater plug back out a half dozen or so turns. Then lower the ram, place a bullet in place on the case mouth and hold it in place as you raise the ram and the bullet enters the die body. As the ram tops out, you should be able to feel if the bullet touches the seater plug. If the bullet does not touch the plug, it will not enter the case. In that event, screw the plug down until you feel the plug touch the top of the bullet (let's also assume the bullet you are using is supposed to enter the case about 1/4 inch when the cartridge is finished). Lower the ram perhaps 1/8 of an inch, screw the plug down to the top of the bullet again, and then raise the ram to its top. At this point the bullet should be inserted about halfway into the case to where the case mouth will eventually be crimped into the crimp groove.

Screw the plug down a little bit more and raise the ram again, thus seating the bullet a bit deeper. Continue adjusting the seating plug and seating the bullet deeper until the top of the case mouth is just at the bottom of the ring above the crimp groove. At this point your bullet should be seated at or very near the correct depth, but it is of course not crimped.

Now is the time to completely reset the die settings to crimp the bullet. First, back out the seating plug maybe a half dozen turns so it does not seat the bullet any further during our next steps. Raise the ram with the seated bullet to the top. Then loosen the die locking ring and screw the die down until it toouches the case mouth again. Lower the ram and screw the die down perhaps a 1/4 turn, hand tighten the locking ring again, and then raise the ram to its top. This will force the case bell out of the case mouth and start the case mouth to crimp into the crimp groove of the bullet. Lower the ram and examine the cartridge. What does the crimp look like? If it needs more crimp, repeat the previous procedure in very small increments until you get the correct crimp. How much crimp? The least that is necessary to do the required job. If you set the crimp too hard and deep, you will buckle the case.

Let's assume at this point you examine the cartridge, and it is seated to the correct depth and crimped just right. Put it back in the shellholder, loosen the locking ring, raise the die a few turns, and then raise the ram to its top (this is the most important key to seating and crimping in one operation). With the cartridge in the shellholder and the ram at its top position, you now screw the die down until the die contacts the finished cartridge on its crimped mouth. Then do a little more than finger tighten the die to insure it is firmly seated on the case mouth crimp. At this point, tighten the locking ring in place. Now you must screw the seating plug down and do a little more than finger tighten it on the top of the seated bullet. Lock the seating plug in place. Your die should now be set to properly seat and crimp the next forty-nine cases sitting in your loading block.

Simply put the next case in the shellholder, hold bullet in place as you raise the ram to its very top, and when you lower the ram, you should have a second cartridge finished just like the first one.

Be very aware that all fifty cases must be the same length and should have their case mouths chamfered. If the cases are different lengths, you cannot get them to crimp at the same spot on the bullet. Keep in mind, once you trim all the cases to the same length and you have chamfered the case mouths, you should not have to do this to these cases again.

I hope I have described how to successfully seat and crimp bullets so most folks can understand the process. If I have missed something, please ask.

So, in final answer to your question, you can seat and crimp your bullets in one operation or cycle of the handle. You do not have to lower the handle twice. You just need to spend a bit of time to properly adjust your seater/crimper die to fit your case and bullet. Once you make the adjustment properly, all the following cases (of the same length) and bullets will seat and crimp in a breeze.

Best wishes,
Dave Wile

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