I'm seeing a 0.015 swing in the OAL of my .308 cartridges about every other one.
I performed a full length size on them all (Black Hills match brass, once fired), seated a Remington 7-1/2 primer, dropped in 42gr of Varget and topped it with a pulled 163gr bullet. I'm shooting for 2.750" OAL and will get that for a couple, then will get 2.735 (ish). It seems if I go more slowly (almost excruciatingly), I'll end up with more rounds on the 2.750".
Any thoughts?
Hey there, MrA,
If those were mine, I'd take a look inside the seating die, and see if it has any crud in it on the seating stem tip....or the bullet tips may not be as consistent as they should be......do you have any variance in your actual bullet length? It might be worth checking a few selected at random with the calipers to see if they have that much error....... @@)
Just some thoughts when I should be going to bed....
Hope you find your culprit....Good luck!
LLP
I agree with LLP. I have seen that much variation with .223. I set up the seater so the longest one will still fit in the magazine. You could always seat to the ogive or uniform meplats...
Crud in the die is a good place to start. Bullet tip damage is a very likely culprit. You may be dinging them a bit when you pull them. Measure bullet length. It will tell you a lot.
Quotewith a pulled 163gr bullet.
When you pull a bullet (either collet pulling or using a kinetic hammer), you can squish/dent/damage the bullet. The bullet is seated via pressure on the ogive, not on the tip.
QuoteIt seems if I go more slowly (almost excruciatingly), I'll end up with more rounds on the 2.750".
Brass is "flexy", too. If you ram the brass then it can wind up pressing the shoulder down, affecting your OAL.
I see a lot of the same thing with some cheap surplus 55gr pills for .223 that I got from Midway awhile back. My OAL variances are entirely due to ogive differences.
Also: I don't see any mention that you are trimming the brass and chamfering the mouth after trimming. If the case mouth length varies and the case winds up getting too long, it can engage the crimping surface of the die before you intend it to (since you set up the die with a case that was shorter). If you crimp while the ram is still attempting to seat to depth, you end up crushing the shoulder down. Do you feel a bit of a "hitch" in the ram on some of these cases that are 0.015 shorter?
Trim and chamfer. Trim to max case OAL minus 0.020. It'll be good for 3-4 firings, or more if you use an RCBS X-die.
I cleaned out the die this AM and tried a couple rounds. One was great, the other was 0.015 short. Seems pretty consistent, it's either on, or not.
I prepped the brass the first time (trim & chamfer) thinking I wouldn't have to do it this time. Perhaps I need to go back and at least chamfer the case mouth. I have the Lee trimmer and collet set, so trimming to length with primers install isn't a possibility.
I don't notice any 'hitch', 'pull', or 'catch', but I can hear when the bullet starts to impact powder. I know that, depending on when I hear it in the stroke whether it's going to be a short cartridge or not. Btw, I'm using a RCBS Rock Crusher.
I measure 27 bullets this morning. IIRC about 11-12 are 1.37 OAL (tip to tail), about 8-10 are 1.38, and there rest are distributed on the far ends of 1.365 (ish) or 1.39 (ish). I didn't have time to make any other dimensional checks prior to my departure to work.
.025" variation in bullet length. Next question is why? Is there that much damage to the bullet tip? Or is the variation coming from somewhere else?
Back off the seat/crimp die so you aren't crimping at all.
Then screw down the seat stem so you seat to the same depth. Lock the die in place and do 10-20 cartridges this way. Measure for OAL.
I think it's a function of crimp and case OAL, augmented by a few thousandths difference in bullet ogive from pulled lots.
Regardless... an OAL variation of 0.020 will impede shot to shot accuracy a little, but they'll still shoot to 4MOA.
Quote from: AZRedhawk44 on March 25, 2010, 02:44:55 PM
Back off the seat/crimp die so you aren't crimping at all.
Then screw down the seat stem so you seat to the same depth. Lock the die in place and do 10-20 cartridges this way. Measure for OAL.
I think it's a function of crimp and case OAL, augmented by a few thousandths difference in bullet ogive from pulled lots.
Regardless... an OAL variation of 0.020 will impede shot to shot accuracy a little, but they'll still shoot to 4MOA.
I'll check that. I shouldn't be crimping much, if at all since I set the bullet seating die (Lee brand) until it just touched the shellholder, then tightened down the die. I have some adjustment left in the seat stem, so I could conceivablely back off the die another 1/2+ turn or so to get even less crimp.
I'll give the suggestions a shot tonight. I plan on sorting out the bullets by lots (+/- .005) and then adjusting the seat stem accordingly as I change sized. I think that's the only way to get repeatable results on this pulled lot of bullets.
My main concern was pressure on the short rounds. I'll have to check my load charts, but think I'm at least 2gr off the max load, so I wouldn't *think* that 0.015 short would drive pressure up so high as to cause me issues, but I got nothing to back up my assumption quite yet.
So what kind of groups are you getting? If the groups are good, why get "tore up" over the overall cartridge length? If not it still may be for another reason.
I can honestly say I don't measure cartridge over all length. Never have. First for me is does it chamber easily without the bullet contacting the rifling? If yes I go to the next step - does it fit in the magazine and feed to the chamber? My groups are fine.
Have you tried different bullets? I used to reload mostly Sierra bullets. The last year or so I've reloaded a lot of "pulled" surplus fmj bullets but groups are fine (at least in the M1 Garand), too.
Ya know, a thought occured to me again....AZ RH brought up a good point about the seating stem pressing on the ogive of the bullet, rather than the tip, which in general, is correct (although not all dies are created equally, and some end up hitting the internal tip of the seating stem).
But not all bullets have the same ogive shape, or contour, either.
And while I am in the same gen'l bunch as OD, if it fits & shoots well, spend less time on the bench, and more time on the line....there are some of my rifle's that seem to shoot a lot better than I do....which makes me wonder why, which leads me into all kinds of late night examinations of arcane things in both the stick, and the boom.....
my thought right now is that you could possibly have a mixed set of pulls, from two (or more) different manufactors......and with a variance in the ogive shape/dimension, may lead to one type to be pushed in a bit deeper......so my question now is, do you have an ogive checker?
By going thru your stock of pulled bullets, you may find some interesting surprises......
Not all bullets that make "mil-spec" are actually created equally..... %)
YMMV, good luck!
LLP
Quote from: Old Dog on March 25, 2010, 05:10:38 PM
So what kind of groups are you getting? If the groups are good, why get "tore up" over the overall cartridge length? If not it still may be for another reason.
I can honestly say I don't measure cartridge over all length. Never have. First for me is does it chamber easily without the bullet contacting the rifling? If yes I go to the next step - does it fit in the magazine and feed to the chamber? My groups are fine.
Have you tried different bullets? I used to reload mostly Sierra bullets. The last year or so I've reloaded a lot of "pulled" surplus fmj bullets but groups are fine (at least in the M1 Garand), too.
This particular load produced groups that were sub-4MOA out of the FAL. I'm not worried about accuracy of this particular round (much). That said, if the rounds aren't +/- 0.010 (which I think even with the most basic setup is achievable), then IMHO, there's some controllable variation in the mix. I don't typically load at max, so anecdotally, I think that tolerance is small enough to keep me from danger.
Other bullets are fine (both air collet pulled and commercial). These bullets seems to have more variation than what I've seen. This weekend, I'll sit down and measure OD in a couple spots as well as OAL length of the bullet.
Yeah, before I blamed a bullet for unsatisfactory group size I'd try another bullet - like commercial fmj (I'm down to buying Hornady's right now at about $22/hundred - but I haven't shot any yet) bullets.
Rifle are funny critters. A change in primers, a change in powder (not necessarily amount, but type used) or a change in bullet (could be the same weight but different brand/type - they are not created equal) can suddenly shrink groups beyond expectations.
Really, you learn more (about the rifle, the reloading and yourself) when you run into problems like this vs. everything working out fine.
In past experiences the batch your using may be from various lots. This happens with just about anything in bulk. I've had some Sierra MK's have .010"+ in OAL due to the closure at the tip. I hope this helps, regards, Tom.
I just tested some loads yesterday in my M1A and had noticed the same kind of variation when I was seating the bullets. I loaded five rounds each with ten different loads of Accurate 2495, starting at 38.0 grains and working up 0.3 grains at a time to 40.7. I was using Lake City once-fired brass, so I wanted to start low and work up slowly and try not to get a surprise. I'm using some 147 grain pulled Israeli surplus FMJBTs. I had sorted them by cannelure type because I noticed I had three different types of cannelures in the lot of 1000 I bought on-line.
I didn't crimp them when seating. I'm using a Lee die set also, so I seated them to the cannelure and then went back with the Lee Factory Crimp die after they were seated to give them a slight crimp. I had the same type of variation (about 0.015" although I had a couple seat shorter and a couple seat longer and I either adjusted the die to reseat the long ones or put the short ones in my inertial puller and gave them a little tap to move them back out so I could reseat them carefully). I had taken apart and thoroughly cleaned the seating die before I used it, so I know it didn't have any crud in it. I also noted that some of the bullet tips were flattened a little. I measured OAL to the tip of the bullet, but I think I'm going to get a bullet comparator so I can measure to a given diameter on the ogive for consistency.
All that is to say that I saw no pressure problems with any of the loads and my best load was with 40.1 grains of AA2495. The group size at 100 yards, prone w/sling and iron sights (the Appleseed way) was just over 1.5". The variation in OAL for those five rounds was 0.008". I had several loads that grouped just over or under 2.0" and one of those groups had a OAL variation of 0.015". I can't shoot much better than 1.5" at 100 yards with irons, so I'm not going to worry too much about OAL variation, other than to watch out for those occasional rounds that are not seated to the cannelure or are seated almost past it. The wide variation IS puzzling, though. I'm a scientist by training and profession, so I'm thinking most of the variation in length is a problem with HOW I'm measuring (hence my proposed switch to a comparator).
I'll post an update if the comparator shows something.
I tore down the reloading setup and started from scratch this evening. In setting up the dead length die (no crimp), I turned it until it kissed the shell holder, then put another 1/4 turn on it to remove any variation. I ran a couple rounds from each batch and am now generally within my (self-imposed) +/- 0.010 in OAL for the batch of rounds. I finished out the batch of 50 pulling bullets at random and they were typically within 5-8 thou of 2.750. I had 3 that came out long (2.765), but another 1/4 of the seating knob fixed those.
I suspect that during my last session, I failed to add the 1/4 turn to take up any slack. I still have variation, but it's less frequent, and repeatable.
"The wide variation IS puzzling, though. I'm a scientist by training and profession, so I'm thinking most of the variation in length is a problem with HOW I'm measuring (hence my proposed switch to a comparator)."
I'm not as experienced at reloading as some of you are but I've had the same problem with variations in OAL with everything from 9mm,.45ACP, .223, and .300 Win Mag. The bullet seaters seem to be generic to work with many bullet shapes. They work well with one shape and not worth a darned with others. I've had great luck takeing the bullet seating guts out, cleaning them up, then fill them with epoxy like JB Weld, and setting a bullet into them till they cure. This form fits to that bullet shape and has greatly reduced the OAL variations both with and without using a comparitor. In the .002"-.005" range instead of .010" or more. This makes the guts dedicated to that particular bullet but the guts are cheap if you shoot various shapes. Just a thought....O.L.
O.L.
That is a classic case of the Rifleman's creed in action...Adapt, Improvise, Overcome! :bow: O0
It is the ogive (generally) that many "seating dies" are working on, and the makers of the various bullets (even within the same company) use different ogive profiles. Some ogive have such a long taper to them as to push the bullet tip/nose into the flattened end of the seating die before the sides contact the ogive shoulder itself, resulting in "squished noses" of the bullets.....
So the radius your die seat is working on will not be the same for each different type/weight of bullet....and, as you have already noted, making a seating tip that is "custom set" for each projectile type & manuf. is indeed a great way to get around the inconsistency issues most reloaders run into.....
Kudos!! A nice "lower cost" method of fixing a common ailment! O0 O0
LLP
O.L.
Yeah, I'm new to reloading, too. Actually just produced my first rounds last Monday and Tuesday for testing. Just to make sure no one understands, I wasn't mentioning being a scientist as any kind of claim to superior knowledge or technique or anything, just trying to explain how my mind works. When I see variation like that, my first thought is to question my methods (technique or equipment). I mentioned the issue to a much more experienced handloader at Ramseur this weekend and was told that if I was just loading rounds for our field shoots (out to 500 yards) not to get too worried about it if the load was accurate. Now, if I were getting into benchrest or 1,000 yard shooting or something, that might be a different story. I've got a few more things I want to look into, just for the sake of consistency and learning to handload as well as I can, but I may not worry too much about it.
I just noticed the original post because I had just experienced the same issue.
Thanks, y'all, for all the input. M.A., I may go back and look at my Lee die setup as well - don't believe I added the 1/4 turn to the die in setup. I want to see if that tightens up my variation as well.
Thought of this yesterday (while loading 250 rounds of .223 for the AR's >:D).....measure you cartridge overall lengths and try to sort by length. Once you've got enough different lengths for 3 or 4 5 shot groups, shoot the groups and see how much the POI changes. It might tell you, better than just hearing someone else say it, that the difference isn't hurting your groups at "normal" distances.
And remember to have fun!!!
I would suggest that you purchase a bullet comparator set. That will enable you to measure your OAL at the ogive vs the bullet tip. As the bullet engages the rifleing at the ogive, this dimension is more critical than the length to the bullet tip. Also, by measureing to the ogive, you can use the same length for any bullet.
The only problem you might have is, if you are using a bullet with a long taper, the loaded round may not fit in the magazine.
Hector