1873 trapdoor load dilemma

[Ks5shooter]

C.O.L. listed for a 300 gr. LFP is 2.465,to load in my rifle I need to shorten C.O.L. to 2.410.Will I have pressure issues? thanks Don

Rifle is a Springfield 1873 trapdoor

 

[rcmodel]

No.

You likely have a different bullet mold design then the one shown in the data.

Seat to the crimp groove on the bullet and call it good.

(And don't start with the Max load!)

rc

 

[Ks5shooter]

Thanks RC and yes I always start at lowest load and go up. Especially in older guns as this. Thanks again

 

[rcmodel]

BTW: 2.410" seems awfully short for any weight 45-70 bullet?

Why exactly do you have to load them that short in a trap-door?

rc

 

[Ks5shooter]

The trapdoor forces the cartridge in if they are any longer.

 

[dprice3844444]

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[rcmodel]

The trapdoor forces the cartridge in if they are any longer.

I still doubt it is the bullet length causing that.

Try this.

Completely 'color' a 2.465" round with a black magic marker.

Then force it to chamber.

Then take it back out and see where the marker ink rubbed off.

That right there is what is tight.
And I betcha it isn't the bullet length.

rc

 

[Ks5shooter]

I made a dummy round with no crimp at 2.465.The cartridge was easier to close door. The C.O.L. when it came out was 2.415.Loaded 5 at 2.410(backed off the lands n groves) and everything cycled easily. When I get back to loading room I will marker a load to see.

 

[rcmodel]

What brand of bullet is it?

What does the bullet measure ahead of the crimp groove? (The part that enters the leade)

What happens if you seat to the crimp groove, and only crimp enough to remove the case mouth bell?

It's just hard to believe any 45-70 trap-door has a throat too short to accept any weight 45-70 bullet seated to the crimp groove.

rc

 

[Ks5shooter]

It is a 300 gr flat point Meister bullet. At 2.415 it lines up with the cannelure closest to the bullet leading edge. I will measure the bullet as well.

 

[rcmodel]

Well, here is the Meister bullet.

The front groove is called the crimp groove.

And whatever length it is when seated & crimped in the crimp groove should work in any 45-70 ever made.

rc

 

[Ks5shooter]

The Meister I have has two grooves forward of the lube, the bullet measures .760 overall length. http://media.midwayusa.com/productimages/880x660/Primary/454/454847.jpg

 

[rcmodel]

O.K..
It has a full diameter driving band ahead of the foreword crimp groove, so it is possible it is getting into the lands if crimped to the rear crimp groove.

rc

 

[Ks5shooter]

So I am good to go then? First time with this old time gun. Although I have been loading for many years for modern guns.

 

[rcmodel]

Do the "'coloring test' I suggested earlier and find out for sure what is too tight.

If it's the bullet seated in the rear groove?
Seat it to the front groove and 'color it' again.

If it rubs in the front crimp groove?
It's case bulge from crimping too much, or not enough to get all the case mouth bell ironed out.

If it rubs on the bullet in the rear crimp groove?
Use the front crimp groove.

That's all you can do with that bullet design.

I suspect it was designed for a lever-action rifle rather then a trap-door.

That's why it has two different crimp grooves.

The rear one is the right OAL & long enough to feed in a lever-action.
The front one is short enough OAL to work in a trap-door.

Just guessing though.

Regardless, trap-door loads are not going to suddenly be dangerous pressure seated to either crimp groove OAL.

Gofer It!

rc