Spring loaded carousel type mags

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Bigragu

Bigragu

Member
Jul 8, 2018
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CA, United States
Has anyone noticed or found out when shooting from a fully loaded, spring designed rotary mag, that groups tend to change as the mag gets closer to empty? Like as if the inner spring over powers the weights of the ammo and causes them to get pushed into the breech cock eyed? I notice when the mag has a few left I see the pellet tip shoved to one side of the mag’s exit hole more so than when full.
Groups seem great at full mag but when 2/3 of the mag gets shot up im noticing my groups start to open up due to stupid fliers. Curious if anyone has noticed this. 


ive never been a single shot, hand fed loader but maybe now I’m seeing why some folks opt to load this way
 
I'm going to start paying attention to this. I do remember from my time testing .30 slugs, that I would get more hang-ups with about 7-10 slugs left in the magazine. This was even with Orion inserts that leave only minimal clearance around the slug. Seemed to be worse with slugs that had a shorter bearing surface, usually the more pointed designs like Varmint Knockers or AVS. NSA it happened less. I only shoot FX hybrids now, and those feed SMOOTH. I have only had ONE rough feed in about a thousand shots.

I never got to the bottom of the hang-up issue since you can't see in there and I didn't feel like pulling the barrel to try and diagnose. I wonder if sprocket speed picks up towards the end and is causing the projectiles to jump a little as they land in the loading position.
 
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Is a hang-up an indicator of the problem or not?



I have had some slugs that didn't gel well with my pellet probe. Seems like if it doesn't feed right or smooth then the problem might be right there. No?



I've owned magazines that contributed to incorrect feed into the barrel. Just more thinking here... Typically that was easy to tell since it jammed once in a while, but not always 
 
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Hang-ups/rough feeding definitely highlight potential accuracy issues. The fact that hangups always happened in the last half of the magazine suggests a magazine component in play. That's not to say it couldn't be probe + magazine, where the magazine component exposes the probe compatibility issue. I would expect the pellet probe to be the most forgiving in feeding since it pushes on the entire perimeter, but I may be wrong there. That is what I am using.

Interesting to consider that the best slug for your barrel may be the worst for your magazine system.
 
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Magazines absolutely effect pellet accuracy with the way they cycle pellets. If the pellet doesn’t line up perfectly with the barrel, or the spring pressure is too high, the pellet can be shaved pushing against the side of the transfer port as it’s loaded. I’ve noticed the impact magazines have pretty tight springs when new. The Orion mags aren’t as tight. I’ve never had issues with my Orion mags. As you know, I had lots of issues with my fx mags. There’s a reason a lot of top tier benchrest guys single load their rifles. Take more mechanical things out of the equation, and you’ll get a better shot. 


This all being said, my understanding of springs would lead me to think there would be more spring pressure when the mag is loaded compared to when it’s going empty. Wouldn’t there be more issues shaving pellets with a full mag? It deserves more testing methinks. 
 
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@ MADEINTHEUK- yes, you are correct in torsional tension being more with a full mag, but I’m thinking theee two things combat that which don’t cause the pellet to push against one side of the entry hole too much, as opposed to when the mag gets a 1/3 or less full now the pellets are pushed tighter to one side-

1. The weight of each pellet x 23(using an fx mag in 30 cal as an example, so 23 x 44.75g)

2. The friction of the heads, the skirts(or both) against either the black main body base or the clear plastic cover. 


all this is assumption. I do know for a fact that pellet probe style will affect the accuracy as i once was using a pin style probe(in which I’m a big fan of) on pellets and for the life of me could not get tight enough groups as I would’ve liked, then switched over to a pellet probe and it was night and day in accuracy. I lost about 15 FPS going back to the probe but the accuracy I got(with a full mag) was way better than with a pin style probe. 

i believe a pin probe meant to push on the very center of an ammo’s base doesn’t get a fair shake when pushing against a pellet or slug that’s already tilted right out of the gate. 


There’s something to be said about circular toothed mags such as those found in the earlier wildcats and some hatsans, that use an indexing lever to rotate the mag. Those hold the ammo perfectly straight and provided the index lever does its job correctly, the ammo gets inserted into the breech perfectly each and every time.

I want to make it clear that I’ve seen the ammo tilt in the marauder type carousel mags, also. I’ve shot the urbans and Daystate revers’s but failed in paying attention to that when I had those guns in my hands, to see. Now I’m wondering if this is just a fault with the heavier 25 cal ammo’s, and for sure tye 30 caliber ammo, and the reason I didn’t see or notice this with the gamo or revere is because they were both in 22 caliber.
 
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FX mags are easy to adjust spring pre-load on, so this area is ripe for some experimentation. I'm running 1.25 turns preload on my mags. There is probably a balance here to run just enough spring tension that the projectile weight and friction is always overcome (no short turning) and not too much tension such that the wheel is slamming the projectile into the loading position. 

In addition to working with the spring pre-load I wonder if adding a small felt washer or something either over or under the feed wheel could provide damping throughout the entire magazine cycle.
 
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Both my OEM FX mags working well with 34 gr pellets or 37 gr slugs, the spring preload is 3/4 turn. Once I am loading 41 grain slugs it is visible that the springs struggling or slow, 44 grain slugs are already way too long for FX mag. I think I will preload the springs for next time 1.25 turns and see how the 41 gr behaving.

I loaded the eaglevision mag with 44 gr slugs and the mag is cycling but clearly visible that the weight is on borderline, have not open it yet to see what is a pre load on spring.
 
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