Deep seat swc

[Deleted]

Im exploring the deep seat option. Ive shot a lot of 200gr swc intended for 45acp through 45 colt by seating over the driving band but never have used heavier bullets. Im starting with the mp 270 saa. Going to try dropping my favored Longshot load of 11.3gr back to 9.3 and test. The regular crimp groove load is 23000 psi level. 
I seated deep enough that the crimp die does not appear to distort the top driving band. The brass does appear to be a bit more bulged than my typical seating. I did not pull a bullet to look at one after seating. These are powder coated clear. They drop in the chambers of the few cylinders I checked. Am I doing it correctly? This load is generally very accurate for me so hopefully I can maintain accuracy, maybe increase it, and save a bit of powder. 
My usual col is 1.65, these deep ones are 1.51

My deep seat dummy rounds with a groove crimped example. 

[markh66]

Seems about right. I usually seat the top drive band to around 0.030 below the case mouth. I then use just enough crimp to remove the flare.

[cas]

Here's what mine look like. They seem to come out the right end of the barrel.

[markh66]

Need to clarify. I'm relatively new to deep seating. I don't want to come across as an expert on this concept. I've been following the guidance of Bradshaw on deep seating for my 44 mag through all the post on this site I could find.

[markh66]

Don't know if you can see it clearly. There isn't much in the way of crimp. I just remove the flare enough to load smoothly in the cylinder.

Attachments:

[blackmamba]

I use a little more crimp than I see you guys using, and never into the drive band like cas shows, but about 10-15 thousandths under the case edge so the roll crimp provides easy loading. The crimp cas shows is what I use with a taper crimp in the 45 auto.

[weiler]

I load the MP 45-270 medium hollowpoint, 278 gr. powdercoated to ~1.520" col over 11.5/HS6 and a Fed 150 match primer, gets about 1,030 fps from a 5 1/2 Bisley Blackhawk and just shoots lights out. I'd like to say I extensively tested deep and standard seating with the solid, cup, large HP, medium HP and Penta but I happened to try this load first on David Bradshaw's guidance and have stuck with it.

[Deleted]

Nov 9, 2023 19:44:42 GMT -5 weiler said:

I load the MP 45-270 medium hollowpoint, 278 gr. powdercoated to ~1.520" col over 11.5/HS6 and a Fed 150 match primer, gets about 1,030 fps from a 5 1/2 Bisley Blackhawk and just shoots lights out. I'd like to say I extensively tested deep and standard seating with the solid, cup, large HP, medium HP and Penta but I happened to try this load first on David Bradshaw's guidance and have stuck with it.

Great info. Everybody I appreciate it.

[bradshaw]

Nov 9, 2023 7:39:55 GMT -5 @professor said:

My usual col is 1.65, these deep ones are 1.51

My deep seat dummy rounds with a groove crimped example. 

*****

Swaging SWC and SWC hollow points from copper cups & pure lead cores----which have no crimp groove----started me on the DEEP SEAT trail. None of the articles I read on swaging mentioned the crimp. The pure lead shoulder of a swaged semi-wadcutter is sharp----and soft. By seating the shoulder .020 to .060 below case mouth, a roll crimp doesn’t distort the sharp yet soft shoulder. Depth was determined by the radius of the crimp die. Accuracy in .357 and .44 mags was superb. My practice continued with hard cast bullets. To deep seat a cast or jacketed round nose, the roll crimp is applied on the ogive. Within

A bullet intentionally devoid of crimp groove
The Bradshaw-Martin .357 194 grain SWC Gas Check has no crimp groove. Elimination of the crimp groove allows for a longer ogive and pushes the COG (Center of Gravity) farther rearward of the COF (Center of Form). And, theoretically at least, adds a pinch of ballistic coefficient. (Note: good Ballistic Coefficient or WIND DRAG RESISTANCE holds as long as the bullet flies straight. Wobble or oscillation instantly degrades ballistic coefficient.) Ogive length if the Bradshaw-Martin 194 is adjusted for COL (Cartridge Overall Length) in the Ruger SRM cylinder, with front driving band .030” or so below case mouth of the 1.605” case.
David Bradshaw

[bradshaw]

Nov 9, 2023 18:34:23 GMT -5 cas said:

Here's what mine look like. They seem to come out the right end of the barrel.

*****

Good looking bullet. Although this bullet has a crimp groove, unless a full load of slow powder required crimping in it, I would DEEP SEAT to bury the front band just below the roll crimp. I wouldn’t crimp on the band. Always want good neck tension on the piston rings, aka wheelbase or bearing surface. (Serious car buffs, Bill Ruger and Bill, Jr., often applied automotive lingo to firearms. Recall, Bill named his Single-Six after a Packard engine and the Super Single-Six after an up-powered version. Bill named his Blackhawk and Bearcat after Stutz models.)
David Bradshaw

[45MAN]

SO GUYS, AFTER 50+ YEARS OF HAPPILY CRIMPING IN CRIMP GROOVES WHAT IS THERE IN DEEP SEATING THAT SHOULD MAKE ME WANT TO CHANGE CHANGE, i.e. WHAT ARE THE PROS AND CONS?

[bula]

I'll start. When not chasing that last nth degree of velo, it will likely gain efficiency. The bigger the case, the more it makes sense. In any magnum that has a special version, it's what is being done. This will save money, on powder. Next ! I've done it in mag cases, to fit longer nosed bullets in a M69. I've done it with hard Penn wide meplat bullets in 480 cases. 

[bradshaw]

Nov 11, 2023 8:31:57 GMT -5 45MAN said:

SO GUYS, AFTER 50+ YEARS OF HAPPILY CRIMPING IN CRIMP GROOVES WHAT IS THERE IN DEEP SEATING THAT SHOULD MAKE ME WANT TO CHANGE CHANGE, i.e. WHAT ARE THE PROS AND CONS?

*****

DEEP SEATING

Pro
* Save 1 or more grains of powder (for same velocity).
* Hold back pressure wave (minutely).
* Reduce muzzle blast (minutely).
* Accomodate longer bullet ogive----chamber rifle bullet in revolver; design SWC with long ogive (Bradshaw-Martin SWC GC).
* Lower extreme spread (for some loads).
* Works with fast, medium, and slow powders.
* Especially suited to cast bullets.
* “Special” level loads in magnum cases; .45 Colt loads in .454 Casull brass.

Con
* Not for full house loads----maximum charge of slow powder..
* Not macho looking.

David Bradshaw

[bigbrowndog]

Rey, like me you are probably already doing it and just not thinking about it. When you load 180 Speers in your 353 for example. When I need to load a long nosed bullet to fit my cylinder for the 414sm. Although we are not using reduced loads, simply making the bullet fit our chamber or cylinder. Crimping in the ogive or anywhere above the cannelure or crimp groove is technically deep seating.

Trapr

[Fowler]

The only other negative I have found is they are a touch slower dropping into a double action cylinder, especially from a speed loader. The rim has a hard flat edge as opposed to a tapered nosed that guides into the chamber.

But outside of IDPA or USPSA is this really an issue? I deepseat stout loads for my Win 1892 45 colt with 270-SAA bullets and they work fantastic.

I also like how you can ID what a load is very easily, deep seated Keith is the mild target load, crimped in the crimp groove is a working load. The nature of trail, hunting, ranch work ends up that there are loose rounds sitting around the truck, SxS, whatever and it is nice to know what that load is assuming you don’t have too many variations.

I find I am utilizing these more and more.