seating depth

[BBS]

Hi guys, let me begin by saying I've been wantin a 204 for about 3 yrs. I finally ended up with a rem 700 lvsf........, anyway I have a ques. regarding seating depth. My oal to the lands is 2.425 I'm loading 35 gr bergers which measure .603 my cases measure1.840.......... If I subtract 20 to 40 thou that means I have around 1/16 of an inch of the bullet actually seated in the case,not to mention, the added slop left by chamfering the case mouth. I was wondering if thats enough to keep the runout in check or if I should go w/seating the bullet .102 which would be half the bullet dia. any input would be greatly appreciated . I would like to say, I've been reading the stuff on this web site for quite a while, there's a lot of great info on here you guys have done an awesome job I hope to be postin some oty pics soon...............

[WrzWaldo]

If I subtract 20 to 40 thou that means I have around 1/16 of an inch of the bullet actually seated in the case,not to mention, the added slop left by chamfering the case mouth. I was wondering if thats enough to keep the runout in check or if I should go w/seating the bullet .102 which would be half the bullet dia.

With A seating depth of only 1/16th of an inch any handling that is less that very delicate will most certainly induce mass quantities of runout. Seat a bullet in a case without primer/powder and see what kind of rough handling it will tolerate. Drop us a note here when you are done.

WW

[OldTurtle]

Most .204s I've come in contact with or read about tend to have a long jump to the lands and they seem to shoot exceptionally well.

It's always been my understanding that a bullet should have at least 1/3 of it's overall length seated inside the case. If that is in error, it's just my understanding and subject to correction.

I have a custom barreled AR upper that was chamber cut with a "short" chamber that still leaves .030 jump to the lands based on a 2.26" OAL for the magazine and was told that any closer and I would be risking excessive pressure problems.

[jo191145]

I always seat the 35 Berg to 2.265 and develop the powder charge for that depth. With the long free bore jump in the 204 we're fine tuning with the powder for the most part. After you find the most accurate charge you can try small incremental seating depth changes. I usually end up right back at 2.265. With the 35 I usually do not even bother changing the depth anymore. Other pills I do because I have less experience with them.

The rules are a little different in the 204.

[WHISTLEPIG]

BBS, I think you should have a minimum of about two thirds of the diameter of the bullet in the case or .136. I guess magazine length could have a bearing on your final OAL also. I actually have increased my seating depth and found a bit more accuracy. I have settled on a loaded round length of 1.957 using my Stony Point comparator. That is about 2.323 measuring the loaded round without the comparator. This measurement will drift a bit due to bullet variations. Over all I have shortened up my rounds by .180 from where I started several years ago. It seems that this round likes a good bit of jump to the lands as a number of members here have reported the same findings as me. I have no data on loading to the lands as my factory Sako barrel will not allow me to get anywhere near them.

[coyotepittman]

If you take a look at Hornady factory loads with a 32 gr Hornady V-Max, they are buried in the neck way up the ogive deep enough it looks like the bullet will fall in the case. I've shot several of these and get consistent groups of 1 inch at 150 yards. They measure 2.871 from the head to the ogive. I seat my Savage to 3.20 from my OAL of 3.38 using a 32gr Vmax and have had no problems with runout. I am particular with my handling but my case neck is tight enough I don't have any problems. I will tell you that those 1 inch groups turn into .25 inch groups with the seating change. Hope this helps!

Meant to mention that the extra inch in the figures above include the stoney point comparator inserts.

[WrzWaldo]

So what are your OAL's base-to-tip?

[coyotepittman]

the 32 gr v-max measures 2.380 from base to tip on a fl sized case. Keep in mind that this is based on my original measurement of the bullet touching the lands in the barrel and backed off a few thou from there. The 2.380 is a finished round that I regularly shoot. Also, after my loads are once fired, I neck size only with a bushing resizing die. If your loads are a bit loose or are having problem with runout, you might try using a neck sizing bushing that puts a bit more tension on the bullet. You will have to watch for loss in accuracy as well as increased chamber pressures the tighter you size the neck. I have recently developed a little problem with a few of my case mouths splitting after firing or resizing. I'm about to post a new thread for some input on that. I hope some of this helps you!
CP

[BBS]

went to the range sunday for a couple hours to try out the various loads I had going. I only shot about 50 of em but the best one yet was seated 2.340 OAL . I loaded half of them up seated 2.380 OAL and the other half at the preceeding length with various charges and got a 1/2'' 5 shot group at 100 now I got a halfway decent starting point but I have a feeling I can get it to do better than that. I'll keep messin w/it. man 10x is a dirty powder (these are just fireforming loads)

[skunkriver]

WHISTLEPIG: You're "right on" with your assessment of 2/3 the diameter of the bullet seated in the case. Here's a quote from Barnes Bullets in the brochure included with 6MM Barnes Triple-Shock Pure Copper Bullets:

"Finally, sufficient neck tension is important. If the bullet is seated too far out of the case, the case neck will not grip the bullet firmly, causing inconsistant ignition and poor accuracy. The minimum amount of full diameter bullet shank gripped by the case neck should be about 2/3 of the bullet diameter."

[WHISTLEPIG]

Thank you Skunkriver, that information came to me via Silverfox a couple of wears ago. Not much I know that has not been thought of first by another.