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HOW TO MEASURE LENGTH OF PULL (LOP) TUTORIAL

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Kim Z.

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Discussion starter · #1 · (Edited by Moderator)
A properly fitted shotgun is essential for accurate shooting. The length-of-pull (LOP) is the distance from the back of the buttstock to the trigger blade front surface. Most off-the-shelf shotguns come with a LOP between 14 inches to 14-3/4 inches. This may be fine for most users, but a custom stock fitted to a particular shooter's LOP will make mounting and pointing the shotgun easier, as well as making it more comfortable to shoot.

Instructions
  1. Stand with your arms at your sides.

  2. Bend your shooting arm at the elbow and hold it at a 90-degree angle with your palm facing up. At this point, your arm should be parallel to the ground, palm open and fingers pointing forward.

  3. Have your assistant use the tape measure to measure the distance from the inside crook of your elbow to the first (outer-most) joint on your shooting finger. Even though this measurement is between your finger and your elbow, as opposed to your finger and your shoulder where it will mount, it is an accurate measurement of your true LOP.
Tips & Warnings
  • Subtract 1/4 inch to 1/2 inch from the LOP measurement if you plan to use the shotgun while wearing heavy clothes or a winter jacket.

  • Always unload any firearm when testing it for fit, especially when testing length-of-pull on actual firearms where your finger will be on the trigger.
 
#2 ·
You would think that the shape of the shooter's face, the length of his or her neck, whether he or she likes to "crawl the stock," the height of the rib (determining whether the shooter adopts a "heads up" style or not , and probably several more differences would have a greater effect on required LOP than arm-length from elbow to finger-crook, particularly since the elbow is bent when shooting and so that particular dimension (alone) does not come into the question at all.

Neil
 
#4 ·
Kim, I do agree that it generally works to get you acceptably close, at least for me. And is as good a place to start to refine things as any. But still, you have to try it and see.

Too short is easy - your thumb hits your nose or glasses or is uncomfortable in some other way.

Too long? A lot harder. I look at people shooting stocks which look too long (by my way of thinking - the nose more than 1/2 or 3/4 or an inch back from the thumb before firing) and still they shoot OK and say it's comfortable. I leave them alone unless asked and they seem to survive.

And, of course, all these collapsible stocks must have some effect on optimum LOP; my guess is that you have to add a bit to protect the nose, but I've never gotten them right anyway, so who knows?

Neil
 
#5 ·
I never saw any reason for using arm length to determine stock length. Picture a shooter with his gun mounted as viewed from the gun side. Now imagine his arm growing longer and shorter - his elbow would move out and in but his head would never move on the stock and the location of his head is what matters.

I had a custom-fitted stock made for the trap gun I use most by Wenig's in 2005. They never even looked at the length of my arm during that fitting. Instead, they changed the length of the try stock until my head was positioned where they felt it should be and used a laser in the barrel to determine the amount of comb height and offset I needed. My arms are of average or normal length for my height but I have a short neck; if my arm was used to determine my LOP, my stocks would be way too long for me.

Two years ago, I had a local stockmaker make a stock for a Remington Model 700 rifle for our daughter-in-law. Stocks short enough for women are hard to find and then they usually are synthetic. He also never did anything with her arm while determining the shape of the stock. Instead, he adjusted the stock length until her head was where it should be and then shaped the comb until she was looking directly into the scope with the gun mounted.

Ed
 
Discussion starter · #6 ·
Ed,

Great feedback! You offer good points. Funny, I have a Browning Superposed and SKS rifle whereby their LOP is so short that I can't shoot them! I feel like I'm holding a kiddy toy. That's the reason which prompted me to start this LOP thread and I was curious as to why my Ljutic felt more comfortable when shouldered compared to other guns.

Kim Z.
 
#7 ·
Very interesting read.

Ed, did you ever compare your stock LOP to the length of your elbow to first joint of trigger finger as suggested by Kim? How much was off?

Said distance of elbow to finger joint might not have anything directly to do with the correct LOP, but it might be one of the magic numbers of human body corresponding to our proper LOP in most cases, because in my case, it's right on.
 
#8 ·
Steve, I have no doubt that for most folks, it's somewhat close - it is for me, too. After all, there was some basis for that old wives tale long ago. But somewhere along the line, we learned about gun fit.

We discovered that close isn't good enough when you're shooting a gun hundreds of times a day. If I shoot a factory-length shotgun stock, I feel like I'm hanging onto the gun instead of feeling "one with the gun." I often get slapped in the jaw by a too-long stock as well. Take just three-eighths or a half-inch off the LOP, depending upon the gun, and it feels very different and much more comfortable.

There is one exception for me, however - the old 870 Competitions. They had stocks that were shaped very differently than other 870 trap stocks and one difference is that the wrist of the stock is longer, thus placing your control hand further rearward, closer to your head. While I had the stocks on my 870TCs shortened, I feel just fine shooting the ones on my Comps at factory length. So as you can imagine, the shape of a stock will also affect what the "right" length is for a shooter and no two manufacturers make their stocks the same - even one manufacturer doesn't, in the case of the 870s.

Another example of that is Krieghoff. The stock on a K-80 bears a lot of dissimilarities to that of a KS/KX-5, as the stockmaker who does my stock work pointed out to me.

In our daughter-in-law's case, every rifle I own had her head positioned near the very rear of the stock, thus placing most of the gun's weight onto her outstretched arms. With her new stock, she can hold on a target much better and is shooting significantly tighter 100-yard groups.

Ask a stockmaker about using the old crook-of-the-arm-to-the-hand LOP measuring system and he'll likely just smile at you if he's tactful and laugh out loud if he's not.

Ed
 
#9 ·
Just for giggles, I just checked some of my stocks as Steve suggested. Wow! Using that method, my 870TC and my 1100TT are too short, my Beretta 687 is too long and my rifles are all over the place, depending upon model (all but one are Remingtons) yet when mounted, all of them feel comfortable and my control hand is about an inch or slightly less from my nose on the shotguns and a little further on the rifles.

Measuring from the trigger to the butt isn't accurate because of the different shapes of triggers and some of them being adjustable muddies the water even more. If you want a gun's LOP to be correct FOR YOU, there is no single universal "shortcut" that works for all people and all guns. You have to put it up and see how it feels, then shoot it to see how it fits.

Ed
 
#10 ·
I can mount a normal LOP stock gun and get the right spacing between my thumb and my nose, about 2 finger widths. If I do the crock of the elbow to the trigger finger measurement, I get 16 1/2" inches. I know which way of fitting works for me. I shoot a large collection of different shotguns successfully, and have no intention of lengthening all my guns to 16 1/2" LOP. Mark
 
#11 ·
Throw in a few other vaiables like the shape of the grip, the shooter's posture, drop at the comb, big chest/big busted and things change very rapidly.

One nice thing about the arm is that it can bend to accomodate. A short-necked shooter who's knuckles may drag on the ground when he walks will still need a short LOP.

When I fit shooters here, it all begins with the placement of their feet and we work up to where their head finally rests ON the stock. I've haven't used the "old wive's tale" of using the arm method for 30 yrs.

Doug
 
#12 ·
I firmly believe that the length of the lower arm is, was, and forever will be a poor way to judge the correct stock length. This is because it ignores the stance used when shooting, the length of the shooter's neck, the correctness of stock's pitch and the height of the gun mount. All have an affect on the correct length of the stock.

I have stated this in the stock fitting guides and books I have written. The only way to effectively judge the correct stock length is with the gun mounted and the distance between the trigger-hand thumb and the nose of the shooter. There needs to be enough separation to avoid the two meeting during recoil. Much more separation and difficulty swinging easily and accurately will arise.

Rollin
 
#14 ·
You are correct; for some weird reason it is a four to one ratio.

Might you be crawling the stock because you mount the gun too low on your shoulder? Is the top of the recoil pad on your collarbone?

Or do you mount it lower because the stock is a little too long for you?

Rollin
 
#15 ·
I'm with Rollin on this. The old Hillbilly method of checking from the crook of the elbow is a poor (at best) way of checking LOP. That just tells you how long your forearm is and that's where it ends.
 
#16 ·
I've mounted a lot a different guns over the years, some were even my own, and each time I added to or subtract from the length, my head placement moved apprx the same as the LOP changed.

When I'm fitting someone here at the shop, and their nose slighly brushes their thumb, a 1/4" or 1/2" addition to the LOP does not move their nose over one inch further back.

Rollin, I'm curious how/why you think this happens. By adding any length, you are only moving the gun forward a small amount, this is assuming you remain with the same body posture, gun placement in the shoulder, and head placement.
 
#17 ·
I had a rebuilt Model 12 with a Anton style rollover stock. It was the most comfortable stock I ever shot. I got rid of it because a pump is a pain to deal with and the price was very right. I'm still thinking of getting a new rollover for my present BT-100. Just a comment for rollovers
 
#19 · (Edited)
I know this thread is old but I need to share my opinion. The measurement exercise is a good way to get in the ballpark. But the LOP measurement is strictly for comfortably. The fact they only one mentioned the most critical measurement “drop at comb” is crazy. All of the other stuff gets thrown out the window when drop at comb is correct. Cast is another crucial measurement. But LOP and Pitch are for comfort.
 
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