Impact of Bipod on Recoil/spotting hits/misses??

[harry_x1]

I just chambered my AI AXMC in 33XC to participate in ELR matches. I already own an atlas bipod but everyone in KO1M type ELR matches seem to be recommending Accu Tac HD with ski feet. Phoenix type bipods are banned in ELR matches now.
How much diff will it make to recoil and ability to see misses/hits if I change from atlas to Accu Tac HD with ski feet, in your opinion? Does it make a significant difference or only marginal? I am primarily interested in recoil and ability to spot misses/hits.
thanks for your time and attention.

 

[K2e2vin]

Why not just put ski-feet on your Atlas?

 

[oneshot.onehit]

I believe the Phoenix is only outlawed at the KO2M and KO1M, they are being used at many of the other events.

osoh
JH

 

[badassgunworks]

You're not going to be doing a whole lot of practicing for ELR with a 33 XC due to the fact that it suffers from massive throat erosion in a very short period of time

 

[Baron23]

View attachment 8084978

BT23: Atlas Ski Feet - B&T Industries, L.L.C.

The BT23 Atlas Ski Feet are easily installed to any V8, PSR or CAL model Atlas Bipod with the press of a stainless steel plunger. They will lay flat in the 90 degree position only. The BT23 deliver a fully articulated smooth foot to support the bipod. Sold as a pair. Available in black only. NSN...

www.accu-shot.com

 

[ma smith]

...everyone in KO1M type ELR matches seem to be recommending Accu Tac HD with ski feet. Phoenix type bipods are banned in ELR matches now.
How much diff will it make to recoil and ability to see misses/hits if I change from atlas to Accu Tac HD with ski feet, in your opinion? ...

Timestamp approximately 32:30,

Paul Phillips - #1 Ranked ELR Shooter​

 

[Dave62677]

Anyone know who made and what’s the mat call? From the video at 33:40. I didn’t catch it clears from the video

 

[harry_x1]

Anyone know who made and what’s the mat call? From the video at 33:40. I didn’t catch it clears from the video

+1 to this question...could not make out name of mat maker...if someone knows, please do share...thanks

 

[Ichi]

Anyone know who made and what’s the mat call? From the video at 33:40. I didn’t catch it clears from the video

The name he says is Ray Gross.

You can turn on the closed captions by clicking on CC in the YouTube window.

 

[Taylorbok]

You're not going to be doing a whole lot of practicing for ELR with a 33 XC due to the fact that it suffers from massive throat erosion in a very short period of time

Barrel's are consumables, and really not that expensive in the scheme of things.

 

[badassgunworks]

Barrel's are consumables, and really not that expensive in the scheme of things.

agreed but is the gain worth the extra expence of short barrel life if you look at the gain on the 33xc that most are running it at its not worth the cost of eroation over the lapua improved but i guess any gain is gain

 

[harry_x1]

Thanks all for the inputs. Finally I settled on getting an Accu Tac HD 50 with ski feet. And it is a night and day diff vs my atlas. With the correct rear rest bag (airfoil), the rifle now moves back into my shoulder vs up/down or too much sideways. This really helps to remain on target and spot misses. I would say that this kind of a bipod is a must for any ELR match. Secondly there were some comments if it is worth to upgrade to 33xc from 338 LM....take my word, it is worth every penny, cent or dime to make that upgrade. You cannot compete in light ELR shooting with a 338 LM or an improved version which is not as capable as 33xc.

 

[Taylorbok]

You cannot compete in light ELR shooting a 338 LM or an improved version

There sure are a LOT of people that say other wise.

 

[harry_x1]

There sure are a LOT of people that say other wise.

am sure many do...but not the top 20

 

[Baron23]

am sure many do...but not the top 20


View attachment 8153063

Sort of wonder why all the Peterson brass. I would have thought Lapua...but, I'm wrong again! haha

 

[harry_x1]

Sort of wonder why all the Peterson brass. I would have thought Lapua...but, I'm wrong again! haha

lol....because Lapua does not make 33xc brass, as yet.

 

[Sandow the Heretic]

lol....because Lapua does not make 33xc brass, as yet.

I find badass being the one warning about short barrel life to be a bit surprising but he is correct. I ran Jay's 338 Edge at CtC and most of the misses were me out to 2100ish. Lower powder capacity but not a hugely different MV than the 33xc. Better barrel life in exchange for marginal loss in performance is probably worth it for most shooters. At Ko1M the last target is going to be in the subsonic range for everything. In Ko2M you can stay supersonic out to the last target with a few calibers so it is attractive to push it there. Not sure it is worth it in Ko1M.

-Alex

 

[harry_x1]

I find badass being the one warning about short barrel life to be a bit surprising but he is correct. I ran Jay's 338 Edge at CtC and most of the misses were me out to 2100ish. Lower powder capacity but not a hugely different MV than the 33xc. Better barrel life in exchange for marginal loss in performance is probably worth it for most shooters. At Ko1M the last target is going to be in the subsonic range for everything. In Ko2M you can stay supersonic out to the last target with a few calibers so it is attractive to push it there. Not sure it is worth it in Ko1M.

-Alex

That makes sense but if one is coming to match with an intention to win it....and let us say that the second last target is on margins of TS, would one rather have higher+consistent MV or better barrell life.....I am fairly new to this so might be off chart here, but in my last spearpoint match my shots kept missing the 2200 yard plate by inches on all four sides without me making much of an adjustment. The only logical reason I could think of was the bullet going TS at 2000. That made me spun up a new faster twist barrel to shoot solids, but that is where I might have gone overboard. None of the top competitors are shooting solids. Bergers seem to rule the roast. Is the better flash the only reason or there could be something else going on here....

 

[badassgunworks]

I find badass being the one warning about short barrel life to be a bit surprising but he is correct. I ran Jay's 338 Edge at CtC and most of the misses were me out to 2100ish. Lower powder capacity but not a hugely different MV than the 33xc. Better barrel life in exchange for marginal loss in performance is probably worth it for most shooters. At Ko1M the last target is going to be in the subsonic range for everything. In Ko2M you can stay supersonic out to the last target with a few calibers so it is attractive to push it there. Not sure it is worth it in Ko1M.

-Alex

The difference between throat erosion and performance When comparing the 33 XC to the Lapua AI and the 338 Edge it's just not worth the slight difference for the amount of throat erosion that you end up having with the XC they're just not that much of an edge in competition to be worth the hassle of by the time your Barrel settles in and you figure out your load you're chasing lands almost immediately having your rifle Go Out Of Tune in between matches for about a 500 round Barrel life at best is just not worth the effort. Sure you can download the thing just under 3,000 ft per second but then what's the point

 

[Taylorbok]

am sure many do...but not the top 20


View attachment 8153063

It's a good choice for sure but I wouldn't doubt if we see some of those top shooters come away from it for barrel life and the fact they aren't running much faster than some of the smaller cases. I've seen that list and there are a lot of the top ELR shooters in the world. I'm sure if you gave half those guys a 338 Lap AI the list would still look very similar. It's a lot more about consistency and wind reading than a couple feet per second

 

[Baron23]

lol....because Lapua does not make 33xc brass, as yet.

LOL...its is not yet clear, I have zero knowledge about ELR. haha

Cheers

 

[Sandow the Heretic]

That makes sense but if one is coming to match with an intention to win it....and let us say that the second last target is on margins of TS, would one rather have higher+consistent MV or better barrell life.....I am fairly new to this so might be off chart here, but in my last spearpoint match my shots kept missing the 2200 yard plate by inches on all four sides without me making much of an adjustment. The only logical reason I could think of was the bullet going TS at 2000. That made me spun up a new faster twist barrel to shoot solids, but that is where I might have gone overboard. None of the top competitors are shooting solids. Bergers seem to rule the roast. Is the better flash the only reason or there could be something else going on here....

If you were all around it in a headwind or tailwind then that was it. Your consistency as a shooter is also a potential cause as is your load. What is your SD like?

Paul hit the last plate there with a 9 twist and 300 Bergers.

-Alex

 

[harry_x1]

If you were all around it in a headwind or tailwind then that was it. Your consistency as a shooter is also a potential cause as is your load. What is your SD like?

Paul hit the last plate there with a 9 twist and 300 Bergers.

-Alex

You might well be right on this one.It was 1130 wind and I am for sure a novice, relatively speaking. I was not measuring my MV during the match but my SDs are in double digits in practice. I plan to put on a bullet seeker from next match for better understanding of these misses. Given all these top shooters are using lead core bullets, I might have jumped too soon on solids. I do see that when it comes to Heavy ELR almost everyone prefers Solids....is there some kind of a bullet weight (caliber) cut off where solids start making sense over lead core....

 

[Taylorbok]

Need to be striving for single digit SD.

 

[Sandow the Heretic]

You might well be right on this one.It was 1130 wind and I am for sure a novice, relatively speaking. I was not measuring my MV during the match but my SDs are in double digits in practice. I plan to put on a bullet seeker from next match for better understanding of these misses. Given all these top shooters are using lead core bullets, I might have jumped too soon on solids. I do see that when it comes to Heavy ELR almost everyone prefers Solids....is there some kind of a bullet weight (caliber) cut off where solids start making sense over lead core....

I'd say 338 is more or less just under the point where solids become better. I've mentioned this before but the full bore surface area of a bullet grows very quickly as the bore diameter goes up. That can end up as a shitload of material to swage. A drive band on a solid can be quite small. At 375, an a-tip will be a bit slower at max than a solid. At 510, the difference is like 400 fps.

-Alex

 

[harry_x1]

I'd say 338 is more or less just under the point where solids become better. I've mentioned this before but the full bore surface area of a bullet grows very quickly as the bore diameter goes up. That can end up as a shitload of material to swage. A drive band on a solid can be quite small. At 375, an a-tip will be a bit slower at max than a solid. At 510, the difference is like 400 fps.

-Alex

If I understood it correctly, you mean to say that the surface area of solid past 375 caliber is relatively smaller than a similar weight/grain jacketed bullet...and the reason is some kind of a drive band?....thanks for your inputs, super grateful.

 

[Sandow the Heretic]

If I understood it correctly, you mean to say that the surface area of solid past 375 caliber is relatively smaller than a similar weight/grain jacketed bullet...and the reason is some kind of a drive band?....thanks for your inputs, super grateful.

The geometry of a solid is essentially unconstrained. Making a swaged jacketed bullet have similar geometry would end up somewhere between expensive and impossible.

If you want most of the shank of a bullet to be on top of the lands in a 50 then it is in the ballpark of .503" but towards the back you have a full bore diameter drive band about .150" long that is .510". In a chamber designed for it, the front shank is on top of the lands once chambered so alignment is done by the bullet rather than careful control of runout. This is a "Bore Rider" which is common in 50 cal and larger but most small solids take a hybrid approach in which the shank is still engraved at least a bit. In the other direction, 20mm bullets have an obvious drive band. So much so that it isn't even seated into the case.

-Alex

 

[harry_x1]

The geometry of a solid is essentially unconstrained. Making a swaged jacketed bullet have similar geometry would end up somewhere between expensive and impossible.

If you want most of the shank of a bullet to be on top of the lands in a 50 then it is in the ballpark of .503" but towards the back you have a full bore diameter drive band about .150" long that is .510". In a chamber designed for it, the front shank is on top of the lands once chambered so alignment is done by the bullet rather than careful control of runout. This is a "Bore Rider" which is common in 50 cal and larger but most small solids take a hybrid approach in which the shank is still engraved at least a bit. In the other direction, 20mm bullets have an obvious drive band. So much so that it isn't even seated into the case.

-Alex

View attachment 8153635

This is super info. I understand now that on large diameter bullets (>375) the solids gain advantage due to drive bands providing lesser friction. However, why is this same advantage not available in bullets <375. For Ex: The bore dia surface area for my badlands seem to be lower than the bore diameter surface area of 300 Berger OTM. Do you think that for same powder charge the solid will be slower vs a lead core in <375 dia?.....I appreciate your indulgence and knowledge sharing...thanks again !

 

[Sandow the Heretic]

Friction isn't really the concern, it is engraving pressures that matter. A solid is harder to swage into the lands for the same length of a drive band as a jacketed bullet cause the lead core will squish around as needed and a solid more or less has to displace material towards the rear. If you've ever resized bullets, the difference is very noticeable between the two. At some point (and lets just say 375) the trade off becomes more favorable towards a short harder to engrave band over a shitload of engraving.

The same charge with both types of bullet will probably get you very similar velocities but the jacketed bullet in larger bores will show pressure signs earlier.

To think about it in terms of friction can lead you down to facile things like Moly coated bullets and magic pixie dust like that.

-Alex

 

[badassgunworks]

Friction isn't really the concern, it is engraving pressures that matter. A solid is harder to swage into the lands for the same length of a drive band as a jacketed bullet cause the lead core will squish around as needed and a solid more or less has to displace material towards the rear. If you've ever resized bullets, the difference is very noticeable between the two. At some point (and lets just say 375) the trade off becomes more favorable towards a short harder to engrave band over a shitload of engraving.

The same charge with both types of bullet will probably get you very similar velocities but the jacketed bullet in larger bores will show pressure signs earlier.

To think about it in terms of friction can lead you down to facile things like Moly coated bullets and magic pixie dust like that.

-Alex

Engraving pressures are increased not only on length of bearing surface but also diameter. Also the property makeup of type of alloy.

 

[cameljockey230]

Harry
On a borerider bullet like a 50 bmg would shoot the front of what would be the bearing surface rides on top of the lands creating very little drag or resistance. After that there is a narrower section called a wasteband that is almost half an inch long that is 0.005 - 0.008 smaller in diameter so it doesn't even come close to touching the barrel. Nearest the boat tail is the driving band which seals the bullet against the lands and grooves and is generally less than a 1/4 inch in length. This is the part of the bullet that imparts the rotational force on the bullet.
So with a solid bullet very little of it ever gets engraved and once it is engraved very little change takes place except near the muzzle.

On a lead core bullet most start out with more than half an inch of bearing surface that is in full contact with the lands and grooves. Lead core bullets obturate or stay in contact with the barrel because of the pressure on the heel of the bullet and the much softer materials that make up a lead core bullet.
A 400 gr lazer will run at 3170 fps while a 390 grain A-tip in the same barrel will run 2970 fps. The lighter bullet would normally shoot faster but due to the amount of bearing surface against the barrel its sees more pressure.

On another post you asked about the bc advantage of various solid bullets and I posted bc and velocity don't mean much within reason.
Some thought that was crazy talk but if you look at your top 20 list you don't see the highest bc bullets winning.
The 3 most important things to winning are
Accuracy
Accuracy and
Accuracy.
Lead core bullets tend to be more accurate and they are way more expensive to make so you don't see them in the larger calibers like lathe turned solids..
In the picture if you can expand it you can see the borerider section the wasteband and the driving band.
Edited: autocorrect killed this post