I have about 600rds loaded up using LC brass, Hornady 68gr BTHP, Varget and CCI #41 primers.  Now I have noticed that most of my rounds are just a little to long and was wondering if it would be safe to just reseat all my reloads .005" or a touch more.  The rounds measure at the ogive 1.844" and I'm using 25.5gr of Varget.  I really don't want to break down every round and start over if I can get away with just seating a bit deeper.  What do you guys think?  Thanks.

it probably will increase pressure.  Just do 2 or 3 and try them first.

So just to be sure I should set them .002-.003" deeper and if I don't see any pressure signs at all and if I need to I can go a little bit deeper?

yes do that for 2 or 3 then try 2 or 3 more deeper if you have to.  obviously examine the brass closely after each fired shot.

Thank you for your help.

I have never had a problem with that. Why would it make difference?

Not 0.005"

Meaning? Don't go that deep or that deep wouldn't matter?

.005 is not going to make a difference that you will see. The only way you can really increase pressure is to seat them way down in or out so long they push into the rifling.

One would have to ask...   how hot was the load to begin with?

I have never noticed one sign of it being hot and my MV is lower than others that use the same recipe.

Won't be an issue.

Thank you.

I just looked for my round and it shows 26gr as max load so I'm still under it by .5gr and almost every load I have worked up for various loads for other guns I always seem to be above max so I'm thinking I won't have a problem seating a bit deeper.  As for this load it's for my AR-15 and I'm not looking for sub-MOA type groups.  So hopefully I don't lose to much accuracy but I'm ok if it drops off some. Thanks for your input.

its not going to matter much, you can try 10 or so just to make sure

but on hodgdon's site for a 69 grain bullet max load is 26 grains compressed, you are still .5 grain under that. not to mention you are barely pushing them in a tid bit further and your still going to be within .223 pressure's

Seating deeper gives the bullet more jump to the lands.  This longer jump Decreases pressure in a bottle necked rifle round, it doe not increase it.

.005 is literally nothing, Most factory ammo will vary twice that.

If that is from the book you're doing it wrong. Maybe you know this.

I just got that number from Hodgdons website.  I never worry about max load. I work up loads until it shows pressure signs and back off a bit.  Almost all my loads are above max.

To the OP...if consult the Hodgdon web site you will see the max load of Varget with 69gr bullet is 26.00...
It is highly inconceivable that you setting the RIFLE bullet back a tad is going to IMPACT pressure..  Now, if you were talking bullet set back with a handgun round well that would be an issue....but with a rifle not a problem...

That's where I pulled the 26gr max I listed above. I don't have my reloading manuals with me.  I do know about the set back with a handgun but wasn't 100% sure on a rifle.  So thanks to everyone that has helped me out.

Ok. The point at which you start seeing pressure signs for a particular combination in a particular rifle is the max load for that rifle, not what is stated in any literature as max. You should have written it down. What is max load for your rifle?

I'm not sure what my max is for this rifle.  I just worked a load up until I got the accuracy and velocity I wanted and stopped there.

Is that a compressed load?  When I was loading 69 grain projectiles with Varget I remember I couldn't even fit 26 grains in the case.

If seating the bullet deeper causes more compression I'd definitely do it in steps, with caution.  If it's not compressing the charge, then 0.005" isn't going to matter.  In fact +/- 0.0025 is probably within OAL tolerance for factory ammunition.

If I remember correctly the powder fills the case to maybe the bottom of the shoulder.  It compresses it a little bit but nowhere near like my 308.

Decreasing case volume = increased pressure.  Just like going from a 115 grain .355 to a 147 grain .355
you will decrease powder to compensate for increased pressure.

I have loaded some Hornady 75gr Matchkings and I seat the bullet deep enough so they will feed from an AR magazine. I called Hornady and told them what I was doing and they said no worry, pressure differential was minimal.

V

Don't really want to get into some kind of technical debate here......just want to say that in my opinion........ it is not accurate and may be unsafe to leave folks with the impression that shorter coals means more pressure than longer coals all else being equal.

The "fact" is (in my opinion) that pressure and coal relative to each other doesn't have to be linear at all...and it isn't.    Pressure can actually rise as you approach the lands ... and can rise again if you touch the lands.

Or taking the opposite approach.......if your are currently reloading your rounds at or near the lands and then decide to seat your rounds shorter thereby reducing coal.....you could actually be reducing pressure as you go shorter - not increasing it.

The reason has to do with the bullet getting a good running start if you will (taking some pressure off) before contacting the lands.  

Its documented.   Google  images pressure change with seating depth and you will find enough data on the subject that should start to convince you to question your thought process if you are one of those who believes its a linear relationship based on case volume alone.  Hornady has written on the subject too.

If that isn't enough....grab you a chrono do some testing and you will see longer doesn't always mean less pressure and shorter doesn't always mean more ...because it can show up as velocity increases/decreases that aren't linear too.

Conversely again.....in some instances reducing coal can increase pressure.

But to simply suggest shorter seating is automatically more pressure and longer is less all else being equal due to case volume alone isn't accurate because it isn't always the case.

That is why folks need to test their own stuff in their own stuff and work up sensibly.

Edit for this..... my rant is based on rifle reloading alone....I have no business spouting off on pistol stuff so pistol guys ignore me (and to some - I may not have any business spouting off on rifle either ) Great thanksgivings to all.    

Rule of thumb, in straight wall pistol brass, seating depth is usually critical as the the internal case volume change can result in a large percentage of difference in the case volume whereas in necked rifle brass, seating depth is less critical for internal case volume because seating depth differences don't result in a large percentage difference in case volume.  The issue with pressure rise as the bullet approaches the lands is a different question altogether.

I read everything you wrote and looked at the pictures in the link you provided but I'm kinda left confused a little.  I'm not looking to increase pressure just looking to make the round a little bit shorter.  So are you saying if I seat them a little deeper say .005" that it could cause an unsafe pressure level?  I just need to make sure before I proceed.  I did originally work them up properly but some of my bullets must have a variance in length and a couple so far after I chamber a round it has some resistance unloading the live round as it went into the lands. Did I misunderstand your post?  Thanks for taking the time to type all of that up for me.

This is true in the .355/9mm straight walled pistol case but it is NOT true in a bottle necked rifle round.  

Note the pressures continue to decrease until the bullet is seated extremely  deep then gradually increase, but never reach extreme pressures even when seated .500 off the lands.



More pressure data.

So according to those graphs I could actually seat my round say .010" deeper and most likely be fine?

.010 is very little adjustment, if any pressure changes were to occur it would be a Reduction in pressure, not an increase.

From John Barsness of Handloader Magazine..

Reducing OAL decreases peak pressure, for two reasons. The longer "jump" of the bullet to the rifling results in a lower peak pressure, since the bullet engraves more easily the faster it's going when it hits the rifling.

Also involved is the "progressive" burning of almost all modern rifle powders. This means the pressure increases relatively slowly from the time of ignition. Thus peak pressure occurs when the bullet beyond the barrel throat, with very slow-burning powders as much as 3-4 inches.

Handgun powders are much faster-burning, and even regressive, meaning pressure peaks when they're first ignited. Thus seating them deeper allows more time for initial pressure to build.

This effect is slightly exaggerated in revolvers. The initial, quick pressure rise is relieved somewhat when the bullet passes the cylinder gap, allowing some gas to escape. When bullets are seated deeper it takes them longer to pass the cylinder gap, giving pressure more time to rise.
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Thank you very much!