Hi all, I'm new to reloading and have come across an issue that I would appreciate some advice on. I measured my cartridge base to Ogive to determine how high to seat my projectiles and realized I have a large jump. I have a Mossberg MVP 5.56 Nato, and I'm shooting .223 brass and shot around 1500 rounds through the rifle. I have been shooting Blitzkings 55gr, so I have heaps of once-fired ADI brass that I will be using. The issue is I used a Hornady OAL Gauge with the full-sized ADI brass (measured 1.750") with using a Hornady ELD-Match 52gr projectile. This measure to 1.988", but that means the projectile only is sitting in the case by 0.166 without factoring for any setback. I thought something was wrong, so I did the Alex Wheeler method and got pretty much the same result. Even a 20 thou setback means the projectile is only sitting in the case by 0.188 thou as the projectile is only 0.802 long. I spoke with a guy down at my local gun store, and he said to set it back enough, so it fits in my magazine, but I bench rest, so I am happy loading the ammo one at a time directly into the chamber. My question is compared to a blitzking, the difference in the CBTO is massive, the blitzking CBTO is 1.836" compared to my rifle, which is 1.988" but factor for a 20 thou setback and call it 1.968", this is still a difference of 0.132". Is this jump too long, and why is it so long? Is it a quality issue? And what would be the minimum seating depth for the 52 gr?
Min projectile seating depth and jump issue
- Thread starter aussiepaul
- Start date
It's likely your MVP has a deeper throat than other models in 223, or the barrel may simply be worn. A borescope camera will reveal the answer.
Generally speaking, seating depth is best at one diameter or more, but for benchrest, as long as the bullet stays seated you're fine. IF you seat the bullet into the lands, you'll probably leave it there if you eject a live round, so be prepared to clear the bullet and powder before you load another round.
The 55 gr V-Max will seat deeper while touching lands. You might also try the 68 gr Hornaday or the 69 gr. Sierra Matchking.
Generally speaking, seating depth is best at one diameter or more, but for benchrest, as long as the bullet stays seated you're fine. IF you seat the bullet into the lands, you'll probably leave it there if you eject a live round, so be prepared to clear the bullet and powder before you load another round.
The 55 gr V-Max will seat deeper while touching lands. You might also try the 68 gr Hornaday or the 69 gr. Sierra Matchking.
Where a bullet may sit to touch lands doesn't matter. You don't need to touch lands with a 223 anyway.
Do full seating testing (like Berger recommended). Then whatever seating is best, use that.
Measure and log that CBTO, develop a load for it, and never change it for the life of that load/barrel.
If you don't want to do this for every change, then stop changing.
Do full seating testing (like Berger recommended). Then whatever seating is best, use that.
Measure and log that CBTO, develop a load for it, and never change it for the life of that load/barrel.
If you don't want to do this for every change, then stop changing.
The 5.56 chamber has more freebore then a .223 chamber. I currently have a rifle in 6.5mm that I single load with only .050" or so within the neck. No problems as long as I don't drop my box of ammunition. Had another .308 Palma with the same issue, no issues at all. Single load and enjoy.
If it really troubles you or you want more control over your seating depth, set back the barrel. Or, depending upon your round count and finances, replace it with a custom and live life to the fullest!
If it really troubles you or you want more control over your seating depth, set back the barrel. Or, depending upon your round count and finances, replace it with a custom and live life to the fullest!
most people dont even know how much shank (bullet surface being "gripped"by the case neck) their loads have,,,,your .224 bullet cant be griped by much more than .200 if seated fully in the case neck,,,its an old wives tale that it must be one cal.(bullet dia),,,,the min. that I use is ~.060" of shank when necessary,,,,if your chamber is so long that it takes less than that I would use a littl jump ,,,if you go less than .050-.060" it is possible to pull the bullet if they are "named" and a live round needs to be extracted,,,,and any less grip and the ctgs. become very delicate and a bullet can come out of the case when loading the rifle ,,,Roger
swd
Silver $$ Contributor
Finding zero at the lands is only a reference point. Do some development and find out where the gun shoots. .186" of bullet in the case is plenty but you also need to take into consideration if it's a boat tail and how much of that is bearing surface. I've seen rifles with long throats that needed the ammo to mag feed shoot very well at over .200" jump. If your single feeding as long as there's enough bullet tension to consistently hold the bullet while loading it your GTG.
All good advice. I have ordered some 68gr BTHP and will also try them. I will try to forget about the jump for the moment and concentrate on finding a projectile it likes and work on powder loads. From there I’ll start stepping the seating out to shorten the jump to a safe level and hopefully it likes the bigger pills. Great idea on the custom barrel but two rifles, two scopes, bench gear, loading gear over the last 9 months has the misses on high alert so might need to keep that one in my pocket. Thanks everyone
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