Seating depth

[pearson1662]

I seem to remember (that in itself is kinda funny, in a sad way) reading in the military section someone recommended seating boolits out till they touched the lands (unless I'm mistaken). Does the same hold true for modern factory rifles? In this case a Ruger M77 MkII Compact in 260 Rem.

The mould is a Saeco 264 dropping a beautiful 143 gr boolit (OAL) 1.095", driving bands .265 as cast and sized .264" which is exactly what the Ruger grooves measure. I have a .266 sizer but it won't crimp the check enough to keep it from coming off in the case. I don't have a .265 sizer but I guess I could open up the .264 sizer with some emory cloth but I'm not terribly handy...

My starting load will be 10.0 gr Unique or 12.0 of Trail Boss.

I would appreciate your feedback.

Jay

[Ben]

Just how tight is the g/c when you slide it up on the g/c shank of your bullet.

Enlarging the g/c shank of the mold isn't rocket science.
That might be you best bet to allow for a good snug locking fit in of your g/c in your .266 sizing die.

You may get fantastic accuracy by sizing to the exact dia. of the groove of the barrel. I seldom if ever
do. I usually size .002 " ( or in some cases more ) larger than the groove.

[Bret4207]

You can also try annealing the GC's, they'll have less spring back that way. Beyond that, yes, I seat out to kiss the lands in the throat.

[JonB_in_Glencoe]

I usually start my seating depth at 0.015" off the lands.
then adjust from there, if I am not happy with accuracy.
Jon

[krag35]

I seat rifle bullets out untill they are lightly engraved by the lands, or untill they will no longer fit in the mag. Revolver boolits I seat out untill they are at least started into the throat. slight push to get them all the way into the cyl. Auto pisol Boolits, I seat as long as will work through the mag.

[pearson1662]

I got off work and started thinking about when I was gonna get to shoot my boolits and realized I would have an extra hour of light this evening. I would have to hurry but the range isn't that far away, so I loaded up the truck raced to the range only to realize I had left the rifle bolt on the bench. %@#$&! I raced home got the bolt, raced back to the range and I was the only one there. I was thankfull. You guys that have beeen doing this for 40 years might laugh but my heart was racing with excitement! I felt like I was looking at my first deer. I set up two targets, one at 50 and one at 25 just in case I wasn't even close at 50. I barely slowed down my breathing and the circling of the reticle to fire that first shot but even through the *** scope I thought I could see a hole in my target.

I know it's only seven shots, not ten. I know it's only 50 not 100 yards. I even used a scope! But they are my first rifle boolit groups, I'm damn proud of them and I want to thank this forum for mentoring me to this point. Now, I'll get to work to make these groups smaller. But if nothing else, I've got a 50 yard deer load!



BTW, the boolits were seated to engage the lands. I shot two more groups, varying only the seating depth. The only difference was higher velocity with the deeper seating by about 40'/sec! Groups were all within a quarter inch.

The gas check isn't tight even with the 264 sizer but I don't think they will fall off in the case. The boolits shank measures .249" The check ID measures .251".

I am tempted to try using valve grinding compound on the shank to open it up to about .253". Does that sound about right?

[NHlever]

Gas check shanks that are too big are more of a problem than those that are too small so go easy when you open that mold up. A .002 press fit is too much, and I would keep it so that the checks are no more than a firm push on, or .251 in this case. It takes very little in those diameters to change it from a loose fit to a press fit. In steel it takes about .0002 clearance to achieve a "slip fit with no shake", and .0002 interference to make a "press fit". as you see, that is about 1/10 of what you are thinking.

[pearson1662]

NHlever,

Thanks for the heads up!!! Appreciated.

Jay

[Bret4207]

Looks like you are off to a great start! Good on you! For the GC's, try annealing them. Just take 20, drop them in your melted alloy and let them get nice and hot, they'll turn black BTW. Then scoop them out and either dump them in water or let them air cool. Either way they'll be softer and won't spring back off the GC shank so much. You may well find they fit your GC shank mush tighter. If not, you aren't out anything.