jtaylor996 Posted October 20, 2010 Share Posted October 20, 2010 I've now setup to shoot the 124gr MG JHP bullets (I ordered a case), and while getting a development load put together I kept noticing a bunch of OAL variances that I didn't get using the hornady XTP 115 gr bullets. I'm using mixed brass (PMC, win, FC, etc...). The variances I'm getting are 0.010", in the range of -.003 to +.010. I'm loading these to 1.100" OAL (so I'm seeing some 1.097", but many more around 1.110"). I know this isn't the largest OAL variance I've seen asked about here, but I'm trying to load very close to my max OAL that will chamber (1.106"), and the long ones are going to get stuck in the rifling... To get the correct OAL I ended up having to run each individual cartridge through the seating die while tweaking the seating depth mic to get the correct OAL on each round. There's no way I'm going to do that when I move things into production and really start cranking these out. I think I've tried to eliminate anything as the cause, but I just can't figure out where it's coming from. Here's what I've done so far: 1. Made sure all stations were full 2. Primers are seating flush 3. Checked the shell plate bolt (over and over) 4. Measured the bullet length using the seating die insert, and all was fine there. 5. Checked that all my dies are inserted fully and locked down tight Am I missing something here, should I be checking something else out? Link to comment Share on other sites More sharing options...
DWFAN Posted October 21, 2010 Share Posted October 21, 2010 I get about .005 avg variance from desired OAL. Isnt enough to matter for what we do. To get better, use 1 type of brass with a Redding comp seating die. Link to comment Share on other sites More sharing options...
jtaylor996 Posted October 21, 2010 Author Share Posted October 21, 2010 I get about .005 avg variance from desired OAL. Isnt enough to matter for what we do. To get better, use 1 type of brass with a Redding comp seating die. What type of insert does that die use? With the Hornady die they have one for FMJ type bullets, and a flat one. I'm using the FMJ type, that seats by the ogive. If the Redding has both, which do you use? Also, why would I see this more than I do when using the Hornady XTP bullets? Thanks! Link to comment Share on other sites More sharing options...
jtaylor996 Posted October 21, 2010 Author Share Posted October 21, 2010 Oh, and I suppose that I'll just have to back off on the OAL some anyways. If .005 is no big deal, then I'll probably be limited to the average OAL of just 1.097" max. I doubt I'll be able to get my variances down to zero, even with that redding die... Link to comment Share on other sites More sharing options...
DWFAN Posted October 21, 2010 Share Posted October 21, 2010 I dont use the competition seater since I dont see a problem with the rounds I produce. I was just suggesting it as an option for you to lower your variance. Why is the XTP better ? Maybe the Ogive is more consistent with that bullet ? I dont know. Mixed brass is enough to give some sort of variance. Link to comment Share on other sites More sharing options...
GForceLizard Posted October 21, 2010 Share Posted October 21, 2010 Oh, and I suppose that I'll just have to back off on the OAL some anyways. If .005 is no big deal, then I'll probably be limited to the average OAL of just 1.097" max. I doubt I'll be able to get my variances down to zero, even with that redding die... Yup that's the answer. You're variance is not a problem. MG JHP are very good, XTPs are more consistent. You may want to try 125gr Zero JHP, sorry drifting. Set it shorter 1.096 or 1.097 and feel good. Link to comment Share on other sites More sharing options...
jtaylor996 Posted October 21, 2010 Author Share Posted October 21, 2010 Oh, and I suppose that I'll just have to back off on the OAL some anyways. If .005 is no big deal, then I'll probably be limited to the average OAL of just 1.097" max. I doubt I'll be able to get my variances down to zero, even with that redding die... Yup that's the answer. You're variance is not a problem. MG JHP are very good, XTPs are more consistent. You may want to try 125gr Zero JHP, sorry drifting. Set it shorter 1.096 or 1.097 and feel good. I guess that makes sense, except that when I use the seating insert and use it to measure the bullets themselves, I only see a variance of like .001", meaning they are way more accurate in length than the variances that I'm seeing. I'd still like to know where the variance is coming from, as it doesn't appear to be coming from the bullet length as the seating dies sees it. I suppose the mix brass may be the issue here. It would be interesting to see if I got the same measurements on the ammo if I measured it as a height from the shell plate, rather than the end of the cartridge. I suppose that is the way that the seating die sees the round presented. A brass variance in the rim geometry may mean that one cartridge brand will sit further up on the shell plate than others. That difference is also probably why the shell plate bolt works itself loose pretty often. Link to comment Share on other sites More sharing options...
DWFAN Posted October 21, 2010 Share Posted October 21, 2010 Whats the variance on the bullet length when you dont use the seating stem to measure ? Link to comment Share on other sites More sharing options...
jtaylor996 Posted October 21, 2010 Author Share Posted October 21, 2010 Whats the variance on the bullet length when you dont use the seating stem to measure ? I don't know. I'll measure that when I get home today. I didn't measure that already because I'm using the FMJ seating stem, which interfaces with the ogive rather than the tip of the bullet (which is what you measure if you measure the bullet length directly). I used the seating stem because I wanted to make sure that there wasn't an ogive variance that was causing the issue. Link to comment Share on other sites More sharing options...
Rob Tompkins Posted October 21, 2010 Share Posted October 21, 2010 (edited) I get the same kind of variance with my LNL using Lee dies including the FCD with Zero 125gr JHP. Using a light coat of lube on the once fired mixed brass reduced it some. If I run one at a time all the way through I get +/- 0.001 variance, or less. IMHO, I think when all the stations are loaded and you use mixed brass you get enough variation in the forces applied to the seating station too cause the variation. I've not tried using new brass from the same lot, it would be an interesting experiment. If you're not using it, try some spray lube (I use Hornady One Shot case lube) and see if it settles down any. Good luck. Rob Edited October 21, 2010 by Rob Tompkins Link to comment Share on other sites More sharing options...
Tul9033 Posted November 16, 2010 Share Posted November 16, 2010 (edited) I've got a LNL with a Redding comp seating die and I also will see .003+/- on MG 124gr JHP. One thing I found is that the tips of the MG JHP's will vary a little bit. If you rotate the round and measure it in several places I bet you will see slight variations. .003 is not gonna make a difference in pistol rounds out to 50 yards IMO. I do see more consistency with like head stamped brass (sorted). Edited November 17, 2010 by Tul9033 Link to comment Share on other sites More sharing options...
jtaylor996 Posted November 16, 2010 Author Share Posted November 16, 2010 I do see variations when rotating the rounds... Does the redding die use a flat seating insert, or one that works on the ogive? What does ips stand for? Link to comment Share on other sites More sharing options...
Tul9033 Posted November 16, 2010 Share Posted November 16, 2010 Sorry fixed a few typos. IPS should have been tips. The Redding does work off the ogive. I do see variations when rotating the rounds... Does the redding die use a flat seating insert, or one that works on the ogive? What does ips stand for? Link to comment Share on other sites More sharing options...
GForceLizard Posted November 16, 2010 Share Posted November 16, 2010 I loaded 3 sets of brass this weekend; CBC, Fiocchi and mixed (really mixed no Win, FC, PMC all odd stuff) The OAL on all CBC and all Fiocchi was very good (+/- .003). The OAL variance on the mixed was +.005 to -.010 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now