aggie dad Posted September 7, 2006 Share Posted September 7, 2006 I did a chrono session today with my new limited G20 for the first time. Was shooting 185 precision bullets at 1.19 OAL, 4.2 gr VV N320 and was getting velocities in the high three hundreds (379, 393, etc.), while the same rounds where exceeding 900 fps in my buddies SVI. I am suspecting there is a problem with the .40/10 KKM barrel, as I don't know what else could cause such a dramatic difference. I am not sure if the chamber/barrel is too tight or too sloppy. Also, had some residue left behind the full length of the barrel that I couldn't clean out with my normal cleaning routine. I have emailed Kevin at KKM and am waiting to hear his thoughts. Anyone else have any ideas? Thanks, Doug Link to comment Share on other sites More sharing options...
Lycanthrope Posted September 7, 2006 Share Posted September 7, 2006 Wow. Did they feel like 300fps? Sometimes chrono's get shifted to meters/sec versus feet/sec......... Link to comment Share on other sites More sharing options...
RifleShooter Posted September 7, 2006 Share Posted September 7, 2006 I had a situation recently in which a particular load in my Glock 19 was showing me fps of less than 200, when I knew that the previous load I tested, which was .2 grains less of the same powder, was giving me 1180fps. It appears that the muzzle blast from the higher powered load was confusing the chrono, but the lower powered loads were not generating enough to bother it. I tested some known velocity ammo before and after the 200fps reporting ammo, so I knew the chrono was good. Is it possible the chrono was too close to the muzzle? Arnie Link to comment Share on other sites More sharing options...
chuckbradley Posted September 7, 2006 Share Posted September 7, 2006 I suspect very strongly that the chrono procedure was in error. Either placement or lighting. I seriously doubt its the barrel unless its a 45 barrel. It takes 5.1 of 320 with a 180 gr Zero bullet loaded to 1.230 to make major in my guns, KKM and schueman barrels. Link to comment Share on other sites More sharing options...
lynn jones Posted September 7, 2006 Share Posted September 7, 2006 it's the lighting. try taking a black magic marker and marking the bullet. this will solve your problem. the profile of the bullet messes up the chrono light things. lynn Link to comment Share on other sites More sharing options...
aggie dad Posted September 7, 2006 Author Share Posted September 7, 2006 (edited) Its not the chrono, we were about 8' away from the chrono and two other guns were also chrono'd under the same conditions without issue, including one other gun that was using my reloads. Also, my gun was not functioning properly either as it failed to return to battery on several rounds. The chrono session was also performed by a top notch female shooter since it was her chrono that was used. Edited September 7, 2006 by aggie dad Link to comment Share on other sites More sharing options...
XRe Posted September 7, 2006 Share Posted September 7, 2006 Could you see the bullets in flight? 300 fps is the typical velocity of a paintball, and you can follow its whole trajectory very easily... Link to comment Share on other sites More sharing options...
aggie dad Posted September 7, 2006 Author Share Posted September 7, 2006 (edited) Could you see the bullets in flight? 300 fps is the typical velocity of a paintball, and you can follow its whole trajectory very easily... No, but we weren't looking for it either. I spoke to Kevin at KKM this morning, and next step is to chrono some factory ammo and see what happens. He thought that since I was using a Precision bullet, it may not be compatible with KKM barrel (too slippery). Then I spoke to David at Precision Bullets and he thinks it is most likely the muzzle blast from the glock that is confusing the chrono. Since the pistol recoil felt normal, and as Nick said above, the concussion from the glock may be whats going on here. Well in any event another chrono test is in order with both factory ammo and reloads, but will move further back 12-15 ft vs 8 ft. It may take me a while to get another chrono done, but I'll let everyone know what happens. Life is always interesting. Thanks, Doug Edited September 7, 2006 by aggie dad Link to comment Share on other sites More sharing options...
Malak Posted September 7, 2006 Share Posted September 7, 2006 lighting or blast, I had a sling shot that made 200fps if not more, and my airsoft cose in at 315fps. If the bullet was drippling out of the barrel at those speeds, you would DEFINITELY feel something different. Link to comment Share on other sites More sharing options...
EricW Posted September 7, 2006 Share Posted September 7, 2006 Why not tear down some rounds and see if you actually have as much powder in there as you think you do? Also, if you really hosed down your cases with lube prior to loading, that can cause problems if the insides of the cases become wet. I'm messing around with Phil Dangerfield's Boeshield trick and there's definitely an effect on my loads if I accidentally get the inside of the case wet with lube. Link to comment Share on other sites More sharing options...
sfinney Posted September 7, 2006 Share Posted September 7, 2006 I've been shooting Precisions 185s out of 2 different KKM barrels this year, no problem - they chrono like any other 180 to 185 bullet. If the same batch of loads runs major in your buddies gun, I'd guess you either have a bad barrel, or more likely, your chrono was off that day, with your gun - due to sunlight, to close to chrono, etc...... My barrels gets coated in a black substance (not lead) from the Precisons.... David Long suggested soaking the barrel in a jar of 50% peroxide, 50% vinegar for 5 or 10 minutes and it will knock the crud right out - a patch will remove any remaing black stuff easily after soaking. (Don't do it to long, or with a non-stainless barrel) Maybe your barrel is so full of crud its slowing the bullet down??? Try cleaning it as above and rechrono. Also, I assumed this was a 40SW barrel, but is this a 10mm barrel? You called it a .40/10 in your post.... if its a 10mm barrel maybe you are getting shearing of lead from shooting to short of a round - 10mm should be @ 1.250 I think. Link to comment Share on other sites More sharing options...
lynn jones Posted September 8, 2006 Share Posted September 8, 2006 (edited) it's the lighting. try taking a black magic marker and marking the bullet. this will solve your problem. the profile of the bullet messes up the chrono light things.lynn bump. what i said. it seems stupid, but the profile of the precision bullets just messes up some chronos. it worked for some poor sole this year at the arkansas sectional. lynn Edited September 8, 2006 by lynn jones Link to comment Share on other sites More sharing options...
Harmon Posted September 8, 2006 Share Posted September 8, 2006 two words, Chronograph error. when i chronoed my trusty major 9mm loads in the blaring bright sunlight and got 2800 fps. iknew something was not right with the chrono. Link to comment Share on other sites More sharing options...
XRe Posted September 8, 2006 Share Posted September 8, 2006 Maybe your barrel is so full of crud its slowing the bullet down??? Try cleaning it as above and rechrono. If the barrel's full of crud enough to slow the bullet down over 50%, I'd think he'd be approaching mechanical failure of the barrel?? (ie, KABOOM...???) Something else that was brought up - is it at all possible that you've got a 10mm chamber and are shooting .40 cartridges? I know that seems like a stupid question (and probably is)... Link to comment Share on other sites More sharing options...
aggie dad Posted September 8, 2006 Author Share Posted September 8, 2006 Although I originally suspected a barrel problem, I believe the problem going on here is the chrono didn't function properly with the rounds shot from my G20. I don't think it is a sunlight issue since my reloaded rounds chronoed as expected from my buddies gun which was done immediately after we got the crazy velocity readings from the G20. As Dave Long advised, he believes it is probably the blast from the glock causing the chrono to trip prematurely. I appreciate everyones thoughts here, but until I can re-chrono at a greater distance and also include some factory rounds, we will only continue to speculate. Hopefully, I can get out early next week and test it again. I'll let you all know what happens. Sfinney, thanks, Dave also told me about using that peroxide/vinegar solution when I spoke to him, and it works beautifully, the G20s barrel is again pristine. Also my KKM barrel is a .40 barrel for use in a G20, its not a 10MM barrel. Thanks, Doug Link to comment Share on other sites More sharing options...
raz-0 Posted September 8, 2006 Share Posted September 8, 2006 I will tell you from experience. With really low numbers like that, it is probably smoke messing it up. I was testing out a 9mm round loaded for my baby eagle in an ls-9. Because of the much shorter barrel, it was smokier. So waht chronoed great form position X started out giving me 1000+ fps, then 700... then low 500s. All within one mag, and they felt the same. (or close enough). I was puzzled for a bit then noticed the slight breeze had shifted and was blowing smoke over the chrono. A little extra distnace and some patience for any smoke to clear the chrono and i was getting much more believable and consistant numbers. I've also gotten too close with a 16" ar and have seen readings in the 5000 fps area. I've mastered a number of stupid chrono tricks, but have not yet managed to shoot mine. It quakes in fear though. Link to comment Share on other sites More sharing options...
aggie dad Posted October 5, 2006 Author Share Posted October 5, 2006 Well, it took me a while to follow-up on this reported issue, but after buying a chrono I got a chance to conduct a reshoot this morning. Good news is all my reloads with 4.2, 4.4 and 4.6 gr of N320, at 1.19 oal, .423 crimp all make major. Its a mind blower to me, how much softer these reloads are vs factory box ammo; boy have I ever been missing out on a major advantage Thanks again everyone for your assistance! Doug Link to comment Share on other sites More sharing options...
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