Question on seating depth experimentation.

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MarkInPA

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I'm about ready to proceed with experimenting with overall length. I found a powder and bullet combination that seems to show promise at .020" off of the rifling. So, I'm going to start loading test groups by seating the bullet deeper in either .005" or .010" increments. I'm kind of curious how far you want to go by continuing to push the bullet deeper and deeper? This is for a hunting round so I definitely don't want the bullet engaging the rifling when chambered. As far as going to deep, I suppose that at some point it would become obvious that your seating too deep and I'm know that you have to be concerned about pressure the deeper you seat your bullet.

On a separate issue, I have a Mauser M98 rifle that has been re-barreled as a .30-06. On this rifle I am limited on the overall length by the length of the magazine. I have stayed away from trying some bullets simply because when I load them to fit inside the magazine, they are a long way from engaging the rifling. A very long jump to the rifling. I'm not sure if I should automatically dismiss the use of them for this reason though. I'm tempted to experiment with them. Any idea how much jump is too much?
 
MarkInPA said:
I'm about ready to proceed with experimenting with overall length. I found a powder and bullet combination that seems to show promise at .020" off of the rifling. So, I'm going to start loading test groups by seating the bullet deeper in either .005" or .010" increments. I'm kind of curious how far you want to go by continuing to push the bullet deeper and deeper? This is for a hunting round so I definitely don't want the bullet engaging the rifling when chambered. As far as going to deep, I suppose that at some point it would become obvious that your seating too deep and I'm know that you have to be concerned about pressure the deeper you seat your bullet.

On a separate issue, I have a Mauser M98 rifle that has been re-barreled as a .30-06. On this rifle I am limited on the overall length by the length of the magazine. I have stayed away from trying some bullets simply because when I load them to fit inside the magazine, they are a long way from engaging the rifling. A very long jump to the rifling. I'm not sure if I should automatically dismiss the use of them for this reason though. I'm tempted to experiment with them. Any idea how much jump is too much?
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As with anything else, YMMV. It also depends on the bullet, some prefer deeper seating by design. I have loaded bullets at .080" and deeper. The bottom-line, find the best COAL/CBTO that your rifle likes. Berger has an excellent article on this topic. Good luck!
 
Depending on the bullet and caliber, after starting off at .020 off, I would start going in toward the lands in .003 increments, and continue up to a .003 Jam which will never pull the bullet out on a hunting rifle.

To go in toward the lands, you have to establish the OGIVE lengths of the bullet you are using, measure and sort them by ogive lengths in some cases. By using this method, you can more often than not, establish some beyond belief groups that repeat time after time.

If you are limited by mag length, jump in .005 increments from .020 off. Remember that Wind does have an impact on groups and flyers.
 
I have only found a couple of rifles that like a bullet seated further than 25-50 thousandths off touching. One was a shillen barreled a-bolt in 284 win. Due to clip restrictions, 2.80 was max and that was like over 175 off and it shot terrific.
 
ShtrRdy said:
Mark Gordon at Short Action Custom did some seating depth experimenting in 0.005" steps.

precisionrifleblog.com

Bullet Jump Research: Executive Summary & Load Development Tips

This is the last post in a series of articles focused on bullet jump research that has been conduct...
precisionrifleblog.com precisionrifleblog.com

Bullet Jump Research

shortactioncustoms.com shortactioncustoms.com
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This looks like some real good information. Thanks for sharing. Interesting enough, although I have found at least two very good loadings, my groups are stringing vertically. If there was no vertical stringing, my groups would be virtually hole for hole. So, I'm encouraged. Perhaps adjusting the seating depth may be the final adjustment that I need to make to bring my groups in to where I want them.

Thanks again. These articles look worthy of archiving for later reference.
 
MarkInPA said:
This looks like some real good information. Thanks for sharing. Interesting enough, although I have found at least two very good loadings, my groups are stringing vertically. If there was no vertical stringing, my groups would be virtually hole for hole. So, I'm encouraged. Perhaps adjusting the seating depth may be the final adjustment that I need to make to bring my groups in to where I want them.

Thanks again. These articles look worthy of archiving for later reference.
Click to expand...
At what distance are you shooting your groups.
 
Dirtrax said:
Vertical could improve at distance. Barrel harmonics may be in play.
Click to expand...
Yea, I've been thinking of that too. I just had my action glass bedded this spring so I hate to consider that. I don't want to think that maybe the bedding job was done poorly. I've already relieved the barrel channel. I have a tight fit with 5 dollar bills being slid down the barrel. Maybe I should relieve that ever so slightly to make it a light fit. I have also been experimenting with different positions of the sandbags. Trying different things to get the rifle to recoil straight back. How can you gauge if the front rest is too hard?
 

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