So with my .221FB/20VT Hornady modified case unusable, I chambered a couple of empty cases with a hand seated bullet, closed the bolt and let the rifle tell me what the oal is. Both cases measured 1.665" using 32gr Sierra Blitzking bullets. I thought I'd start with the bullets seated .005" off the lands and see what happens. What I'm not too sure of is that with the bullet seated at 1.660" there is only about .045" of the bullet seated into the neck. Is that enough?
20VT, I think I'm finally ready to load and go shoot some paper
- Thread starter BaconFat
- Start date
If I'm correctly following exactly what you have done, the measurement you have found is not "at the lands" but "jam" a measurement of the bullet jammed into the lands.
Take a look at the bullet when you do this and I bet you find engraved marks on the bullets where they were pressed into the lands. Slowly seat deeper and deeper until you no longer see those marks and then you are "at the lands", or very close to them.
Some people start at the lands and work in or out, often time depending on the style of bullet. Other people start at jam and work their way out. If you start at jam, especially with a small capacity case like the 20VT and fast burning powder like H4198, be sure to start at the lowest recommended powder charge and very slowly work up.
.045 isn't a lot of bullet to have in the case. I have a few rifles with deep throats but still have at least .100 of the bullet in the case. Some people say you should have a full caliber of bullet inside the case, but I don't know if there is a lot of validity in that. Could be true in a repeater with lots of recoil...you don't want the bullets working out of the case. How much neck tension you run certainly would be a factor.
Hopefully someone more experienced will voice an opinion about this.
Take a look at the bullet when you do this and I bet you find engraved marks on the bullets where they were pressed into the lands. Slowly seat deeper and deeper until you no longer see those marks and then you are "at the lands", or very close to them.
Some people start at the lands and work in or out, often time depending on the style of bullet. Other people start at jam and work their way out. If you start at jam, especially with a small capacity case like the 20VT and fast burning powder like H4198, be sure to start at the lowest recommended powder charge and very slowly work up.
.045 isn't a lot of bullet to have in the case. I have a few rifles with deep throats but still have at least .100 of the bullet in the case. Some people say you should have a full caliber of bullet inside the case, but I don't know if there is a lot of validity in that. Could be true in a repeater with lots of recoil...you don't want the bullets working out of the case. How much neck tension you run certainly would be a factor.
Hopefully someone more experienced will voice an opinion about this.
Otter, you're right. I guess my measurement would be from jam since I basically let the bolt seat the bullet. To add a bit more info. My rifle is a new, unfired Cooper model 38. Since the first 25 rounds are for break-in purposes I'll start with the bullet seated .150" into the neck for five rounds and add .005 seating depth for each of the next four, five round groups.
I also have a model 38 in 20 vt but my seating depth was determined by the action opening. What I mean is that if loaded to touch the lands they would be to long to eject a loaded round. The good news is that I have been able to shoot many groups in the .1's and .2's. I think my oal with 39 sbk is 1.87"
Just took some measurements for you BaconFat, but keep in mind I'm using 32 grain Hornady Z-max bullets. I have a model 21 Cooper. Typically I would expect they used the same or similar dimensioned reamer, but I certainly wouldn't assume that. Looking at your numbers it appears your rifle has a longer throat then mine.
I seat my bullets several thousands off jam. With a comparator, my loads measure 1.513 from the base to the ogive. That leaves about .135 of the bullet in the case, give or take.
32 grain Zmax bullets measure .274 from base to ogive and 32 grain BlitzKing bullets measure .310 from base to ogive. I've never found different bullets ending up with the same OAL length, so when I test the BlitzKing bullets I expect them to be different, but I also expect more of the bullet to be in the neck.
Addendum: I just measured from base to tip and came up with 1.876. If Varmintshooter is measuring from base to tip, we are very close to each other as to where we are seating them.
I seat my bullets several thousands off jam. With a comparator, my loads measure 1.513 from the base to the ogive. That leaves about .135 of the bullet in the case, give or take.
32 grain Zmax bullets measure .274 from base to ogive and 32 grain BlitzKing bullets measure .310 from base to ogive. I've never found different bullets ending up with the same OAL length, so when I test the BlitzKing bullets I expect them to be different, but I also expect more of the bullet to be in the neck.
Addendum: I just measured from base to tip and came up with 1.876. If Varmintshooter is measuring from base to tip, we are very close to each other as to where we are seating them.
So after spending a little bit of time determining the longest oal that would eject, I came up with 1.900 oal and 1.545 base to ogive with the Sierras. My limiting factor is to be able to readily eject an unfired cartridge. I don't want to have to be fooling around with the ejector to release the cartridge if I'm at the range and everyone is waiting on me for the line to go cold.
Rick in Oregon
Gold $$ Contributor
I load my Cooper M38 20VT with 32gr NBT's loaded .005" off the lands, and I also have the "loaded round ejection issue". But as I never shoot at any range, usually out in the open desert among the junipers, other folks waiting is not an issue, but a real PITA out in the field when you want to stop and clean and you've got that dang loaded round in there.
Personally, I want accuracy above all else, and this issue pretty much does not bother me enough to seat bullets deeper to satisfy the ejection problem. The answer: Don't chamber a round unless you intend to fire it. Problem solved. (Yeah, I know, I'll still be faced with it now and then too.)
I'll let the rifle decide where to seat the bullets and deal with the short ejection port now and then. When the rifle will shoot like below, would you want to ruin the accuracy by seating deeper just to eject a loaded round now and then? Not me.
One thing for certain.....these rifles shoot, and the 20VT shoots like it was designed for BR, not rats.....but I'll take it in a M38 Cooper just the same and deal with it.
Personally, I want accuracy above all else, and this issue pretty much does not bother me enough to seat bullets deeper to satisfy the ejection problem. The answer: Don't chamber a round unless you intend to fire it. Problem solved. (Yeah, I know, I'll still be faced with it now and then too.)
I'll let the rifle decide where to seat the bullets and deal with the short ejection port now and then. When the rifle will shoot like below, would you want to ruin the accuracy by seating deeper just to eject a loaded round now and then? Not me.
One thing for certain.....these rifles shoot, and the 20VT shoots like it was designed for BR, not rats.....but I'll take it in a M38 Cooper just the same and deal with it.
I suppose what I'll do is load up 25 rounds at 1.90 oal for break-in purposes. This will give me a couple to send off to Hornady to have them make me a modified case. While I'm waiting on getting that back, I'll load some batches seated longer and just see what happens.
It's time to get off the pot.
It's time to get off the pot.
Rick in Oregon said:I load my Cooper M38 20VT with 32gr NBT's loaded .005" off the lands, and I also have the "loaded round ejection issue". But as I never shoot at any range, usually out in the open desert among the junipers, other folks waiting is not an issue, but a real PITA out in the field when you want to stop and clean and you've got that dang loaded round in there.
Personally, I want accuracy above all else, and this issue pretty much does not bother me enough to seat bullets deeper to satisfy the ejection problem. The answer: Don't chamber a round unless you intend to fire it. Problem solved. (Yeah, I know, I'll still be faced with it now and then too.)
I'll let the rifle decide where to seat the bullets and deal with the short ejection port now and then. When the rifle will shoot like below, would you want to ruin the accuracy by seating deeper just to eject a loaded round now and then? Not me.
One thing for certain.....these rifles shoot, and the 20VT shoots like it was designed for BR, not rats.....but I'll take it in a M38 Cooper just the same and deal with it.
Rick that is a great shooter. I would not change a thing either!
Regards, Paul
www.boltfluting.com
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