Fire forming and resizing

[ShooterSteve]

Plus one on the safety part. Sometimes we forget that we are engineering a small explosion that will be taking place with in a few inches of our face, eyes, fingers, etc...

[cardiackid]

Well I fired the original cases again today with the same load (42gr Varget, 168gr SMK) and saw little to no change in the shoulder length (with still a decent spread across the measurements). What I did notice is that my longer shots were dropping more quickly than the handful of data sheets I have so I'm assuming that load isn't close to 2600fps. Unfortunately I don't have a chrono to confirm. I did shoot better today though - finally remembered to bring my sand sock and forgot how much of a difference that makes.

Also noticed that in addition to the chamber length being extremely long (2.055 on mine when I gauged it), apparently the lands are pretty far out there as well - or at least a lot farther than I thought they would be. I figured I could barely seat and then jam a handful of bullets and then use the micrometer seating die to knock them off the lands slightly. However I found that despite the COAL being 2.813 on one of them it still wasn't even kissing the lands as loading the round did not cause any change in the bullet seating depth.

I guess the large dimensions in a factory barrel have to be a standard, as the majority of users are going to fire nothing but commercial/SAAMI spec factory ammo. Just didn't think there would be this much of a tolerance gap - who knows.

It's off to find a chronograph now. I'm at the point where I realize that although there are many good things with regard to handloaded ammo, all I'm doing when it comes to shooting is firing consistent rounds that are nowhere near the intended velocities, etc.

Anyone have one chronograph versus another to recommend? I'm assuming the Pro Chrono Pals/Digitals and the others that are recommended for the USPSA guys would work just as well for high power rifle? Thanks.

Edited March 20, 2011 by cardiackid

[Graham Smith]

I've seen several people remark that for 168gr bullets, they have better result with IMR 4096. Not sure why except that it is a slightly faster powder.

[ShooterSteve]

If you are having trouble getting the 168s to get to the lands, give the 175s a try. The bullet has a longer front, and will reach the lands better. I had trouble getting the 168s to get out on my factory chamber, but the 175s worked great. I always thought that the bullets were similar, just different weights, but the bullets are shaped different, and are just built different from each other. The 168 bullet was specifically designed for shooting 600yd matches. If you are like me, once you spend hard earned money, it's hard just to give something else a whirl, but just keep this in mind the next time you buy some bullets. One other thing to stir the pot, many people are having good luck with the Nosler 155s at long range, but obviously these will be a little shorter, so they may not reach your lands as well. I have a box of them, but haven't been able to take the time to work something up with them. Too many projects and too little time...

[highxj]

Unfortunately, most factory chambers have unnecessarily long throats and neck lengths. Are you trying to jam into the lands for the sole purpose of fireforming your cases, or hunting for top accuracy? It's not really necessary to jam into the lands while fireforming, in fact with the smaller calibers it doesn't even work anyway. When the firing pin strikes the primer it either drives the bullet farther into the case neck and/or farther into the lands. You shouldn't have enough headspace with factory brass to worry about case stretching, a decent load will form the case perfectly.

As far as accuracy, with my small caliber varmint rifles I always begin load development with square land marks on the bullet. I always order my reamers with zero freebore so I can accomplish this as well as chase the lands as the throat wears..I then fine tune bullet seating depth, but the best accuracy isn't *always* found with the bullet into the lands. I realize with the 308 you'd need a certain amount of freebore to accommodate the long bullets....

How is your accuracy?

[cardiackid]

I was only jamming those bullets for the purpose of fire forming. My thought was that even with it being a lighter load, the additional pressure of a jammed or nearly jammed round (.001/.002 off) would help with the fire forming. It didn't.

The sole purpose of this ammo is for distant steel target shooting (500m to 1000m)

Accuracy was great (for my standards/ability) anyway - certainly couldn't blame the bullets/ammo. When I confirmed my 100m zero yesterday my cold bore was about .75" away from the next 2 shots although I can't say whether or not that's typical yet as I've only started recording my shots recently. The next two shots were touching. After adjusting 1 minute up and 1 minute right I was just right of the X about 1" and that shot grouping was .397" from center to center at the farthest point so I was happy. I honestly think I'm just getting a little better at shooting and the handloads are more of a placebo - I've been reloading for longer than I've shot precision rifle so I think I'm starting to get in the groove of shooting the bolt action versus the hoser 3-gun stuff (usually 50m and in) that I was always shooting before.

It's looking like with the factory Remington chamber it would take me a while to actually stretch the brass enough for a truly precise fit. I think I may be better off just standardizing my handloads to verify that the shoulders are consistent, neck length and tension is consistent, and most important my powder charge and seating depth according to ogive. The 168gr SMKs I purchased a while back so I don't mind "wasting" them developing my brass as I've read the 175gr are more tailored for the distances I want. I do have 200 rds of 175gr SMKs waiting for when I get my chrono to actually build a consistent and well working round for my weapon.

I'm finding out now why people pay good money for custom chambered barrels, etc. as it does take a lot of the guess work out and makes load development easier. It's kind of like my platoon sergeant told me when I first got into reloading and bolt action rifle shooting - "Don't buy Norma or Lapua brass until you can appreciate it." I see what he's getting at.

[Powder Finger]

I think once you get a BB speed-o-meter you are well on your way.

Previously I posted about not knowing what 42 varget with 168 SMK were like in "YOUR" gun pressure wise, I'm sure you are light to get the speed you are after.

You may not as mentioned get on the lands, and not to take away from experimenting, but you will probably find something off the lands that shoots great. I've even got 168 VLD's to shoot under .75 min @ 600 consistantly at mag length.

One other note to make: If you just want to get your chamber len cheaply, get a piece of fired brass from different guns (friends) you should get one that's longer than your chamber. Now you can size to just fit your's then you will have your number.