How much jump do you use?
- Thread starter AKD
- Start date
.010 - .015" is my default starting point, too. I generally don't have to change it unless I've got a confounding accuracy problem.
If you're jamming .020", aren't you just pushing the bullet back in to the case? If you extract a cartridge with a bullet seated for a .020" jam does it still measure the same length as it was before chambering?
Very interesting topic, Me and AKD just use the gauge to find my start point, which was very surprising, fairly big difference between the manual and what we found. Pretty excited to start some load testing changing the different jump. My previous loads from the manual i would have had crazy jump, which might explain why at 89.0 gr i was seeing pressure signs on my brass, id have to go look but thats still about 4.0gr below my max powder load.
rnbra-shooter
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Good method (removing firing pin assembly from bolt; easy on Winchester M70 and Savages, requires a tool for Rem 700). Also a very good method to assess how much you are sizing your cases.
Do realize that if you are making land marks on the bullet, you are actually jamming the bullet a *lot* (as in ten, twenty or even thirty thou).
I would have some concerns about this method. One is that resized brass is likely to have headspace and cause error. The other is that bullet seating tension is going to affect your results (when do you feel resistance). I jam 0.010" and never feel it on the bolt. I'll post the method I use at the end of this. I've looked at the Stony Point (Hornady now) system, but do not feel it offers any better, even if you get a fired case case from your gun threaded to the tool.
Another issue in all this is that bullets vary in bearing surface length. They also vary a lot in distance between the bullet seating cone contact point and the ogive to body point. Can be over 0.010". So, unless you measure every single loaded case for accuracy with a bullet comparator, it is extremely poor practice to be seating to "kiss" the lands, or really anywhere less than a 0.010" jam or jump. You are in no mans land, and can have bullets jammed or jumped depending on tolerance of the bullet, and then the resulting affect on pressure and accuracy. Just my thoughts...
Split Case Method
1. Take a neck sized only fired case, and use a Dremel to cut a single narrow slot in the neck and shoulder.
2. Select a bullet from the box you plan to load and fit it in the split case. Pick a bullet with a consistent flat tip, or file it a touch to square it up. Adjust case by squeezing the neck to increase tension as required. It does not need a lot of tension and just enough hold the bullet.
3. Carefully chamber it, and remove it slowly. If the ejector is pushing the case sideways, use your finger to keep the bullet from dragging on the side of the chamber or receiver.
4. Measure the overall length of the cartridge to the tip of the bullet, and record it.
5. Repeat step 4 until you get consistent numbers within .001". When you think you are close, then just pull the bullet a slight touch out from the self seated position and confirm it consistently returns to that same spot, and record the final length of the cartridge, and record in you loading book. Mark this bullet so you don't mix it up with the rest.
6. This length represents what overall length you need for that specific bullet to touch the lands. In my opinion just touching the lands is a poor position to seat too. I go either 0.010" longer to jam the bullet, or increments of 0.010" shorter to create a jump to the lands. Calculate your desired OAL to give the jam or jump you want, and record that number.
7. Use this marked bullet to load a live round long in the case, and by seating it deeper and deeper by trial and measure match the OAL you have calculated in step 6.
8. At this point methods may differ. Some save this load and use it to set up your die for the next loading session. I have a micrometer style seating die, so I just record the seating position in my loading book and use the test round at the range.
9. This test load, or recorded seating depth in theory is good for that specific batch of bullets, if it were not for throat burning. Especially when new the throat burns so is a moving target. So, especially with a new barrel you may want to repeat this exercise more often, or if you bought a large batch of the same bullets.
Thease are all the methods I talked about. Btw when you use the removed firing pin method you use a fired un sized round.
Some methods work ..... But still telling ya, hornady OAL guage is the best tool hands down.
Some methods work ..... But still telling ya, hornady OAL guage is the best tool hands down.
A flat screwdriver can be used to remove a remington firing pin assembly.
http://www.youtube.com/watch?v=RK89W2jJ838
There is another way using a penny that I use but can't find the video.
Watch the video Moose 284 posted and you will see why.http://www.youtube.com/watch?v=Jv-D1mEI514
With the firing spring in a remington the bolt cannot close freely without resistance because the pin sear catches on the trigger sear and the firing pin spring tension pulls back on the bolt causing the bolt lugs to bear on the lug seats which prevents the bolt from free wheeling to the closed position. Yes the plunger extractor in a remington pushes on the case slightly but not enough to stop the bolt from falling freely enough to do a test like what is illustrated in the video.
Does this problem apply to Savages as well? From my reading about setting headspace on a barrel, I've only seen recommendations to remove the ejector.
Also, I have another more basic question about this process: Do you first find the right powder load, and then tune seating depth? Or does it sometime need to be the other way around? So many variables.... I'm hoping mag length works well in my rifle, because I want to use the mag.
