Cast Boolits Seating Depth Thoughts

[Uncle Grinch]

I was pondering over some new loads this evening and got to thinking... (sometimes this is dangerous or at least tiresome). To digress for a moment: I used to work with an older gentlemen who would comment..."There you go again, working without your tools!".. everytime I said "You know, I was THINKING...

Anyhow...

Most of us want the best accuracy we can get from our loads. With "J" bullets we try to kiss the rifling for that magic load. For some reason I have never tried this with my cast loads. Possibly because I have been trapped to thinking "inside the box" so either my rounds are seated to the crimp groove (if it has one) or because I don't like to expose the lube to the elements.

With gas checked boolits I find myself seating them out just so the gas check is retained inside the neck of the cartridge, assuming the round will feed and load properly. Some of my boolits have a very short grease groove sections, ex... 311299 or 314299. Others, like my 311291 or my RCBS-26-140-FN have a much longer grease groove section. These last two require the gas check to be well below the neck in my .308 and until lately, in my Swede. It has a fairly long throat and will handle longer boolits.

My quest for accuracy has been redefined since I started shooting in the Vintage Military Rifle Match our club sponsors (www.marionroad.com (http://www.marionroad.com)). I need all the help I can get to compete with some of our shooters.

What do are your thoughts on this topic?

[NVcurmudgeon]

The first step in determining overall length for me is finding the length at which the boolit is just touching the rifling. I use the masking tape on the cleaning rod method to learn the distance from the bolt face to the muzzle, then push a boolit into the chamber and measure the distance from the nose of the boolit to the muzzle. The difference between the two marks on the tape is starting overall length. I then seat a boolit to the starting OAL and see if the grease grooves are covered and if the cartridge can function through the magazine. The starting OAL is then altered depending upon what the purpose of the ammunition is to be:

For plinking loads, working through the magazine and keeping the grease grooves covered are more important than the last tenth inch of grop size.

For competition loads, various OAL are tried with best accuracy the only goal, here, and exposed grease or magazine feeding all but ignored. Engrave the boolit
while chambering, or just touch the lands, or seat it deeper to see if that is best?

Most of the cast bolits used in my rifles are from moulds designed to be suitable and convenient for the cartridge in question. Almost always I load boolits that are of the generally accepted middle to heavy weight range for the caliber. the one thing I don't ever worry about is seating the gas check below the case neck.

All of the above is not cast in concrete, intended purposes and individual rifles will dictate changes. Experiment, you'll find somethng you like!

[Blackwater]

Can't give any testimonials about rifles yet, but I had a fairly recent experience with the Lee 45-130-TC bullet that some may be interested in. Initial tests seated it what I THOUGHT was deep enough. It jammed the pistol pretty consistently, so seated it about .025" deeper, and voila' - no more jams! The gun ate them like they were sugar coated. One other thing is that the Lyman manual listed the 230 gr. LRN at a max. load of Unique of 7.2 gr. That was well over 1000 fps., so I knew immediately it was way too hot. Backed off to 6.8 gr. and got the Lyman listed velocity with the 230 RN of 965 fps. A buddy used two of those to take two deer this past season. Both one shot kills that couldn't have gone better with a howitzer. Seating depth in the short autopistol ctgs. can make a BIG difference, so use the chrono to be sure you're OK with a new load.

[Harry O]

I have been seating my cast rifle bullets out to get closer to the rifling for some time. That usually leaves some (but not all) lube grooves outside of the case. I put them in a plastic box between loading and shooting, so they are not picking up lint in my pocket. It does seem to help. The only problems I have seen is when the bullet remaining in the neck is too short (usually with "standard" to "light" bullets for the caliber -- "heavy" bullets are not a problem).

[Dale53]

Many, many years ago, I was heavy into IPSC. I was using a borrowed #68 H&G mould with a recommended (and good) load. Shot lots of it. No problems. Then I had a chance to buy a nearly new H&G four cavity mould with handles. However, it was for the #130 bullet. They are completely different semi wadcutters of nominal 200 gr weight. I thought that the #130 seemed a little hot (with the same powder charge) but continued on my way.

One day, when cleaning my pistol I noticed two cracks in the slide. I started an investigation to try to determine if the slide was just "fair wear and tear" or if I had done something that caused it. First, "I weighed" the recoil spring. It had "sagged" to 12 lbs instead of the issue 16lbs. Then, I chronographed my load. I was shooting that bullet at over 1100 fps. It picked up 200 fps just because it seated deeper in the case (lowered the case volume). I installed an 18# spring, installed a Wilson Shok-Buff, and reduced the powder charge until the chronograph told me I was "OK". Never a burp after that.

I now routinely "weigh" my springs, change out the buffer at regular intervals and live by the chronograph. I also know, that the chronograph is no substitute for a pressure gun, but I do what I can with what I have.

So, yes, seating depth (and associated case volume is EXTREMELY important).

Oh yeah, I bought a new slide and had it fitted...

Dale53

[Bret4207]

Wth bolt guns and a new boolit I put a sized and lubed boolit in an un-crimped case and seat it long. Then I either push until the bolt closes or keep adjusting the seater till the bolt closes. A couple more fresh rounds and I have to nose in contact with the lands and I set the die from there. With lever guns I leave it just kissing or a bit short. With auto pistols you pretty much have to load for feeding. With revolvers I go for the crimp groove out of fear of the boolit moving. The Lee Factory Crimp Die may change my mind on that.