REDESIGN: 7.62x25 Boolit

[jdgabbard]

I've been toying around with a redesign of a boolit for the 7.62x25 that I had done back around 2010. The original boolit, which I used Mountain Molds for, can be seen here: https://bulletmatch.com/bullets/moun...ulds-311-90-rf

At the time I designed this we were still faced with the problems of traditionally lubed boolits in the 30 Tok: It has a short case neck without much room for lube or a gascheck. Because of this many existing designs would work, but were not optimal in my opinion. Because of this I worked up the design you see there. Several other similar designs came about during this time frame. One I know was designed by Al, and is almost an identical clone except for some differences in nose profile and weight, being a little lighter at 85gr if I remember correctly.

The problem I saw with these designs was the amount of lube they could carry as well as not having a gas check in most cases. However, now we have Powder Coating... And as such really shouldn't be limited by the Tok's short case neck.

The boolit I had previously designed shoots well both traditionally lubed as well as PC'd. However, without a gascheck I feel it is somewhat limited where velocity was concerned. Remove the lube groove, add a gascheck, change the meplat from .184 to .200 (65% instead of the original 60%), and adjust the ogive to give a slightly better BC for use in my 7.62x25 rifle project. Ultimately what I came up with is what you see below. It should come in at 90gr as cast, and right around 95gr once PC'd and fitted with a gascheck. I've toyed with a HP design as well, which looks like it should cast around 85gr, and 90gr with PC and gascheck, but is just an idea at the moment...

I'm looking for any comments, critiques, concerns, etc.

[45_Colt]

Interesting design. At a minimum I would include a crimp groove. They need it due to the bottleneck and short neck design. So far the three different manufacturers ammo I've used have been crimped into a groove (j-words at that).

45_Colt

[jdgabbard]

Interesting design. At a minimum I would include a crimp groove. They need it due to the bottleneck and short neck design. So far the three different manufacturers ammo I've used have been crimped into a groove (j-words at that).

45_Colt

You think it's needed? Just speaking from my own experience, but I've never had an issue without having one. I just Tapercrimp into the front band. My previous design has done fine without one, but I'm open to considering it.

[Misery-Whip]

Ive loaded 100 grain 32 cal XTPs without a crimp groove. Lee factory crimp was used.

I like the design. Id prefer it to be closer to 100gr. But your the artist.

Whats this rifle project?

[jdgabbard]

Ive loaded 100 grain 32 cal XTPs without a crimp groove. Lee factory crimp was used.

I like the design. Id prefer it to be closer to 100gr. But your the artist.

Whats this rifle project?

You can read a short post on the rifle here. It’s nothing super special, but I do have high hopes for how it turns out once I have some decent sights added…

https://castboolits.gunloads.com/sho...adger-30-Reece

I too like the idea of a 100gr option, but it pushes the length to the point that it might be over Max OAL. Not so much in length. But the edges of the meplat might start interfering with some magazines. Obviously you can see deeper, but then you either have to delete the gascheck or seat it below the neck - something I’m not convinced is ok. I know with my previous design it fits CZ52 mags just fine, but it doesn’t have a whole lot of extra room. The nose of this is a little longer even though the overall boolit length is the same. That said, 95gr with a gascheck is a nice compromise between 90 and a 100…


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[Bigslug]

You think it's needed? Just speaking from my own experience, but I've never had an issue without having one. I just Tapercrimp into the front band. My previous design has done fine without one, but I'm open to considering it.

While it's not going to be needed for recoil-pulling, as in revolvers, 45_C may be hinting at setback due to feed dynamics of certain guns (?). I don't know what the extended Tokarev family of pistols and subguns does for impact (nose vs. case shoulder) on the feed ramp, but it's worth remembering that our Red friends didn't move much beyond RNFMJ with the concept. I'd coat the nose of a round with dry-erase marker, chamber it, and then make a study of where the hits are. If they're all ogive impacts, I wouldn't consider a crimp groove any further. If the edge of your meplat is getting some rollover, I'd at least think about one.

I did some noobie experimenting a few years ago with the fat meplat 452423 .45 Auto Rim bullet through various 1911's. While I got it to feed, there was a definite hitchy-kerchunky feel in how the gun ran that suggested it wasn't happy at the prospect, and the noses were absolutely getting deformed going up the ramps. Your bullet profile is nowhere near that extreme, but it's a good cautionary tale about letting the guns - which in your case are military and designed without consideration for variety - tell you what they will accept.

[45_Colt]

You think it's needed? Just speaking from my own experience, but I've never had an issue without having one. I just Tapercrimp into the front band. My previous design has done fine without one, but I'm open to considering it.

On a single shot rifle, set back isn't going to be an issue. But who knows where this is going to go. Maybe a lever action next, or an auto pistol. There is no harm in having a crimp groove, and it is better to lightly crimp into it then into the boolit itself.

Another reason is that some powders like a little additional pressure when lit off. Even a light crimp into a groove will help in this regard. There isn't much neck tension with this little cartridge, so every bit helps.

45_Colt

[jdgabbard]

While it's not going to be needed for recoil-pulling, as in revolvers, 45_C may be hinting at setback due to feed dynamics of certain guns (?). I don't know what the extended Tokarev family of pistols and subguns does for impact (nose vs. case shoulder) on the feed ramp, but it's worth remembering that our Red friends didn't move much beyond RNFMJ with the concept. I'd coat the nose of a round with dry-erase marker, chamber it, and then make a study of where the hits are. If they're all ogive impacts, I wouldn't consider a crimp groove any further. If the edge of your meplat is getting some rollover, I'd at least think about one.

I did some noobie experimenting a few years ago with the fat meplat 452423 .45 Auto Rim bullet through various 1911's. While I got it to feed, there was a definite hitchy-kerchunky feel in how the gun ran that suggested it wasn't happy at the prospect, and the noses were absolutely getting deformed going up the ramps. Your bullet profile is nowhere near that extreme, but it's a good cautionary tale about letting the guns - which in your case are military and designed without consideration for variety - tell you what they will accept.

I'm a little limited in my ability to test for this, as I only have a CZ52. Which is a roller locked design instead of a tilting barrel browning design such as the TT33. So I cannot say how the TT handles the feeding. But on the CZ the barrel's ramp and the frame's ramp impact the front half of the ogive feeding very smoothly into the chamber. Smooth to the point that I don't have any flat spots on the boolet when chambering... So it's pretty dang smooth....

On a single shot rifle, set back isn't going to be an issue. But who knows where this is going to go. Maybe a lever action next, or an auto pistol. There is no harm in having a crimp groove, and it is better to lightly crimp into it then into the boolit itself.

Another reason is that some powders like a little additional pressure when lit off. Even a light crimp into a groove will help in this regard. There isn't much neck tension with this little cartridge, so every bit helps.

45_Colt

Well, there is a certain level of harm in the addition of the crimp groove from a technical perspective. If the goal is to create a boolit which is gaschecked, which rides entirely in the caseneck, and offers a tanget ogive (something that is a good idea given shorter leads of the Tok's chambers) with a flatpoint, bearing surface is also limited. If you look at how much bearing surface it actually loses it isn't insignificant, about 25%: 0.133" compared to 0.183". For a boolit intended to truck along at +/- 1500 FPS, possibly up to 1700 in longer barrels, you definitely want more bearing surface if possible. Though this design does have a bore riding nose, it isn't very long, only about 0.050". And it's hard to add more, again due to the chamber of these guns have relatively shorter throats. It's easy enough to mock up, here is an example, I'm just not certain it is a great idea:



With all of that said, most everyone I've seen loading for the tok uses one of four molds: Lee 311-93-1R, Lee 311-100-2R, Accurate 311-075S, Accurate 311-085G, or occassionally with the Accurate 100g variant. These last three I believe were based on my original design, but I cannot be sure. It does seem several nearly identical designs all popped up at once.... However, what all of them have in common is that none of them have a crimp groove. If someone is interested it a crimp groove it's easy enough to drop in a variant, that may possibly help someone in their particular pistol if it is hard feeding. Even if I'm not convinced, someone else might need it.... But that is assuming there is enough of an interest in this eventually do a group buy and get it on the books with one of the mold cutters....which I'm not certain there is. Group buys for the Tok have been tried in the past and I don't believe they garneredd much interest...

[GONRA]

Waaaaaay back GONRA gotta special LYMAN mould:
31356S Just one lubegroove.
102 grains. Sized .313 inch diameter
Verks Just Fine for me in 7.62mm Tokarev loads.....

[barnetmill]

You think it's needed? Just speaking from my own experience, but I've never had an issue without having one. I just Tapercrimp into the front band. My previous design has done fine without one, but I'm open to considering it.

The 7.62x25 is also a submachine round and I can see a need for a bullet well secured by a good crimp for SMG, but not so much in a single column pistol magazine.