Minimum bullet/neck engagement?

[Huntnful]

Curious what some people's preferred minimum bullet engagement inside the neck is, on 7mm and larger. And what is the absolute bare minimum you would go, or have gone and still had excellent consistency and accuracy?

 

[QuietTexan]

0.001" and about 0.120" of the neck sized (6mm so roughly half-caliber) is the lightest I found looking through my records. Probably could have used 0.0005" under caliber for the neck size but was already sizing such a short length of it I didn't go less. The problem with doing that light of treatment is that it doesn't necessarily make a durable round that can be bounced around or run through a mag.

I do half-to-three quarters length of neck sizing on a lot of things (including big 300s) but run tighter fits, -0.002" or so. Not to the point the bullet is expanding the neck. The amount of expansion a neck can take before yielding varies with caliber, smaller calibers take less interference than larger ones. Seems like this big "don't be an blankety blanking blank and neck size only" kick going on where everyone insists on FL sizing cases kicks aside the nuance of using a separate body die and neck sizing die that gets to the same point. "Always FL size your cases" doesn't mean you still can't vary length of neck sized using a bushing die. I should probably be more anal about trimming more often but length of neck sized seems to be pretty forgiving in that being off a thou or so in length doesn't drastically change things as much as sizing down in the neck/shoulder junction.

Sample size of one, I'm sure other people will be along that have the opposite experience. I've talked to one shooter I highly respect about this and he says you can never control length enough to matter and that custom honed FL dies are the way. Another says honed dies are trash. Lots of opinions, which is why YOUR targets are the only ones that matter.

 

[Huntnful]

0.001" and about 0.120" of the neck sized (6mm so roughly half-caliber) is the lightest I found looking through my records. Probably could have used 0.0005" under caliber for the neck size but was already sizing such a short length of it I didn't go less. The problem with doing that light of treatment is that it doesn't necessarily make a durable round that can be bounced around or run through a mag.

I do half-to-three quarters length of neck sizing on a lot of things (including big 300s) but run tighter fits, -0.002" or so. Not to the point the bullet is expanding the neck. The amount of expansion a neck can take before yielding varies with caliber, smaller calibers take less interference than larger ones. Seems like this big "don't be an blankety blanking blank and neck size only" kick going on where everyone insists on FL sizing cases kicks aside the nuance of using a separate body die and neck sizing die that gets to the same point. "Always FL size your cases" doesn't mean you still can't vary length of neck sized using a bushing die. I should probably be more anal about trimming more often but length of neck sized seems to be pretty forgiving in that being off a thou or so in length doesn't drastically change things as much as sizing down in the neck/shoulder junction.

Sample size of one, I'm sure other people will be along that have the opposite experience. I've talked to one shooter I highly respect about this and he says you can never control length enough to matter and that custom honed FL dies are the way. Another says honed dies are trash. Lots of opinions, which is why YOUR targets are the only ones that matter.

I should have made it more clear that I'm talking about seating a bullet into the neck. Not neck tension lol. Sorry about that! But I appreciate the detailed response!

 

[lancetkenyon]

I try to seat base of bullet at or just above body to shoulder junction if possible. Seems like that is a real sweet spot for accuracy in a lot of different cartridges. Not always possible though. A lot depends on the chamber/throat, FB, and bullet length being used.

I have heard time and again that bullet diameter is a minimum for neck to bullet contact, but I have not necessarily found that to be true. I have a couple that with a short neck and a long boat tail, that only about 1/2-3/4 of the neck are holding the bearing surface towards the case mouth.

Here is a 7SAUM w. 175 Elite Hunters

 

[yankee outlaw]

bullet dia is what they call the safe zone

 

[Huntnful]

I try to seat base of bullet at or just above body to shoulder junction if possible. Seems like that is a real sweet spot for accuracy in a lot of different cartridges. Not always possible though. A lot depends on the chamber/throat, FB, and bullet length being used.

I have heard time and again that bullet diameter is a minimum for neck to bullet contact, but I have not necessarily found that to be true. I have a couple that with a short neck and a long boat tail, that only about 1/2-3/4 of the neck are holding the bearing surface towards the case mouth.

Here is a 7SAUM w. 175 Elite Hunters
View attachment 386308

Perfect. That's exactly how I like mine seated also. Curious if anyone has pushed the depth to .125 or less also. That looks like about .200 of the bearing surface in the neck, which I would prefer. Hell maybe I'll just test them seated out extra long with hardly any bearing surface engagement lol

bullet dia is what they call the safe zone

Yeah, that's like old wive's tales. Highly unnecessary.

 

[codyadams]

I have found consistency with very little neck engagement in a couple cartridges, it takes a good thump to move the bullet, as long as you have proper neck tension. Just run that 220 LRHT in your 300 NMI out to .010" off and see if it shoots good, if it does, run 5 through your magazine and check to see if CBTO has changed ha ha

 

[Huntnful]

I have found consistency with very little neck engagement in a couple cartridges, it takes a good thump to move the bullet, as long as you have proper neck tension. Just run that 220 LRHT in your 300 NMI out to .010" off and see if it shoots good, if it does, run 5 through your magazine and check to see if CBTO has changed ha ha

haha I wish I would have just started with them seated way out there just to test them now. But my thinking was "If they don't shoot with at least this much bullet in the neck, then I don't want to shoot them anyways".... and now I want to know hahahaha.. of course.

 

[HSmithTX]

I try for a caliber length of bearing surface in the neck of the brass, so maybe .250-300" in a 7mm and .275-.325" in a 30 cal. With that said I will go more or less depending on what I need to do. If it has to mag feed and I have a short mag box I will stuff a bullet well down into the powder space. If I have a long mag box and I need to get close to the lands to get it to shoot the way I want I will go as low as 1/2 caliber of bearing surface in the neck. If it gets less than that I will try to find a point with a long jump that gets the accuracy back. Lately I have been setting everything up with a long jump, I have had some loads in the past just hammer 10 thou off the lands but if they are 5 or 15 off the lands accuracy falls off quickly. When I can get a load to hammer with a jump of 40-120 thou it seems in my limited samples that the window is much much wider, sometimes over 20 thou without any meaningful difference in accuracy. I load on the close end and let throat erosion take me through the window with no real decline in accuracy. Lots less fussing with loading and keeping an eye on throat erosion.

 

[Huntnful]

I try for a caliber length of bearing surface in the neck of the brass, so maybe .250-300" in a 7mm and .275-.325" in a 30 cal. With that said I will go more or less depending on what I need to do. If it has to mag feed and I have a short mag box I will stuff a bullet well down into the powder space. If I have a long mag box and I need to get close to the lands to get it to shoot the way I want I will go as low as 1/2 caliber of bearing surface in the neck. If it gets less than that I will try to find a point with a long jump that gets the accuracy back. Lately I have been setting everything up with a long jump, I have had some loads in the past just hammer 10 thou off the lands but if they are 5 or 15 off the lands accuracy falls off quickly. When I can get a load to hammer with a jump of 40-120 thou it seems in my limited samples that the window is much much wider, sometimes over 20 thou without any meaningful difference in accuracy. I load on the close end and let throat erosion take me through the window with no real decline in accuracy. Lots less fussing with loading and keeping an eye on throat erosion.

Excellent info! Thank you for sharing!

 

[Huntnful]

I have found consistency with very little neck engagement in a couple cartridges, it takes a good thump to move the bullet, as long as you have proper neck tension. Just run that 220 LRHT in your 300 NMI out to .010" off and see if it shoots good, if it does, run 5 through your magazine and check to see if CBTO has changed ha ha

That's a jammed 220 on the left. Maybe .01 into the case neck. That's it seated .05 deeper on the right. Once they're jammed, they normally contact the lands pretty heavily for about .06

I'd imagine stuffing one up from the mag could possible throw out concentricity a decent amount with that little in the neck?

A 195 Berger was over .100 from Jam to where it started to not contact the lands any more.

 

[QuietTexan]

I should have made it more clear that I'm talking about seating a bullet into the neck. Not neck tension lol. Sorry about that! But I appreciate the detailed response!

Ah makes sense. I wouldn't be concerned until you're at less than half-caliber in the neck. I think the two components (tension and seating depth) kind of pair up... if only half the neck is sized then as long as the base of the bullet is below the sized portion it doesn't really matter how much/little is in the neck because the grip isn't changing and release isn't impacted any more. Doesn't matter if it's the front half or the back half of the bearing surface being gripped, it's only so much there to hold. So I guess my answer could be extrapolated to mean keeping the base of the bullet below the sized portion of the neck maximizes useable case volume . That would be analogous to below the neck/shoulder on an FL sized case.

I also set up throats to have ~0.040" of jump built in with the base of the bullet at the bottom of the neck, so I don't have a chamber to where I'd be less than 0.100" in the case neck with a reasonable bullet. Seems like a good set up a chamber would be to size half the neck, get a 0.020" jump, and have the bullet base below the sized portion of the neck and above the neck/shoulder junction. That's what I set my last reamer up for and I'll see how it goes.

I could do something dumb like put a 110gn TAC-TX in a 300 RUM and have a massive jump with 0.100" in the case neck, but that's not a reasonable combination to start with.

bullet dia is what they call the safe zone

And also is impossible on many cases, the 300 WM being the prime example because the entire neck is shorter than one caliber length.

 

[WeiserBucks]

I'd imagine stuffing one up from the mag could possible throw out concentricity a decent amount with that little in the neck?

Absolutely correct.

Also, without much neck "grip" on the bullet, depending on the throat, mag length ect. you'll likely have COAL growing during recoil affecting the rounds in the magazine. Not ideal if your preferred load is seating depth sensitive.

 

[codyadams]

View attachment 386333
That's a jammed 220 on the left. Maybe .01 into the case neck. That's it seated .05 deeper on the right. Once they're jammed, they normally contact the lands pretty heavily for about .06

I'd imagine stuffing one up from the mag could possible throw out concentricity a decent amount with that little in the neck?

A 195 Berger was over .100 from Jam to where it started to not contact the lands any more.

load up 5 with a .010" jump and run em through your mag and check them again. That doesn't look like much engagement, and I would guess there is a fair chance it could get messed up from feeding, but ya never know until ya try. Lot's of people told me my 20" barreled 30 nosler would be intolerable to shoot and give less performance than a .308 win, but it's pleasant to shoot sending 215's at a shade under 3000 fps, so ya might as well try it ha ha you won't be out nothing. You don't even have to shoot any to test them ha ha