LOP for Free Rifle?

[GlennC]

Greetings all,

I've been reading this forum off and on for a few years, but only recently registered.

I recently swapped the stock from my Anschutz 1411 (prone rifle) for a used and modified 1413 (free rifle) stock. The 1413 stock had been shortened by a few inches for reasons unknown, and I was made aware before the swap. I can calculate the proper LOP for a "standard" stock, but am not sure if the same method should be used for a free rifle stock. I'll be adding material to the 1413 stock and will be probably be using it the both a hook and flat adjustable buttplate.

I appreciate your thoughts and experience.

Glenn

[Tim S]

Glenn,

Anschutz Supermatch stocks seem to be a bit under 11in from the rear of the buttplate to the front of the grip (with the butt wound fully in). Typically the xx13 Supermatches are shorter than the xx11 Prone stocks to suit the Standing and Kneeling positions. To compensate for this Sxx13 stocks all have and adjustable length butt, thst can be run out on rods. If your stock doesn't have this, it's either been removed, or is a 1409 not a 1413.

That said LOP depends on height, arm length, shoulder breadth, chest size, body angle, position height, and not to mention stock/grip shape. There is no one size fits all standard. To fit your position properly, i.e. to avoid straining your arm and shoulder, LOP needs to be set individually.

[patriot]

Glen, You might try the short LOP if you haven't worked out your personal fit. New shooters often make it too long.

Mark

[Martin H]

Hi Glenn
Maybe this will help.
As a starting point when setting up new shooters in a prone position, I use the following formula:
1 Measure the length of arm. Arm at the side, measure from inside armpit to longest fingertip.
2 Butt plate to trigger LOP = 1/2 of total arm length measurement.
3 Handstop to trigger length = 1/2 of total arm length measurement, minus 50 mm (2 inches)

Example
Total arm measurement = 660mm.
Butt plate to trigger LOP = 660/2 = 330mm
Handstop to trigger = (660mm/2) - 50mm = 280mm

These measurements are intended as a starting point. As Tim has pointed out, the varying body shapes require different measurements.
Cheers
Martin

[GlennC]

Thanks for your thoughtful replies. The stock (which is bored for the 1413 buttplate, which has been removed) has been shortened probably 2-3 inches. Currently, the LOP (rear of triggerguard to butt as cut) is about 7 3/4" inches. Included was an adjustable hook with LOP adjustment that will reach to about 10" at full extension. I'd like to add material (probably aluminum) to make a more secure mount and add some potential length.

I realize that ultimately LOP adjustment will be a matter of experimentation. Being unfamiliar with this type of stock configuration, I was curious if there were any special considerations.

Martin: thanks for the suggested starting point. I'll start there and see how it goes.

Again, my thanks for your responses.

Glenn

[Tim S]

Glenn,

LOP once adjusted for the same individual, should not be that different between a 1411 and a 1413. The Supermatch buttplate can be raised higher to make better contact with the shoulder, and shunted sideways or canted to bring the sights in front of the eye, but the basic butt-grip distance won't be that dissimilar. What the 1413 does do, that the 1411 doesn't, is bed the action further back towards the shooter. The trigger blade will normally need to be positioned further forward with a 1413 stock than a 1411, but there is less barrel out past the shooter's support hand.

Yes 1411 stocks do have a longer butt than most, because back in the 1960s and '70s (when these were made) Prone positions were generally low, much lower than today, which suited a long straight butt. These butts are often a little long for those of average height and under, in a modern position. I've seen many club shooters struggle with a rifle that's just too long at the back, because they either don't know any better or refuse to alter the rifle.

A 1413 shortened by 2-3in; that's quite a bit. It's been cut what an inch or so behind the thumbhole scallop?

[patriot]

I made these two spacers out of aluminum for a friend; a lot of work. Cut them out on a band saw, ground them to the trace line, then filed them by hand to get the angles correct.

Mark

012410_11062.jpg (37.21 KiB) Viewed 1367 times

[GlennC]

Tim: as cut, the distance from the rear of the thumbhole cut to the butt is 4 1/4" on the cheekpiece side. Not sure how this compares to an unmodified stock, but it seems pretty short.

Mark: I envision making spacers very similar to yours, which look very nicely made. Unfortunately, no band saw available, so it'll be a lot of grinder/file/sandpaper work. I'm trying to size my aluminum bar stock as close as possible to the finished dimensions to minimize that, but still see significant perspiration in my near future.

Here's a picture of what I'm working with:

[BigAl]

Tim: as cut, the distance from the rear of the thumbhole cut to the butt is 4 1/4" on the cheekpiece side. Not sure how this compares to an unmodified stock, but it seems pretty short.

Mark: I envision making spacers very similar to yours, which look very nicely made. Unfortunately, no band saw available, so it'll be a lot of grinder/file/sandpaper work. I'm trying to size my aluminum bar stock as close as possible to the finished dimensions to minimize that, but still see significant perspiration in my near future.

Here's a picture of what I'm working with:

Compared to my 1813 stock that looks to have lost about half of the distance from the rearwards end of the thumbhole (about 2" or so). That is really short. I guess at some time it must have been shot by a lady, or very small junior. Possibly with the lighter 1407 barrel fitted.

Alan

[patriot]

Yep, it will be a good workout for your hands. A sanding drum in a drill press came in handy. Try to collect/control the dust, there have been tests that found aluminum in Alzheimer's patients; others have refuted the results.

Mark

[Tim S]

Glenn,

there is a broken 1413 stock in my club locker. If you would like, I'll measure the butt tonight, to give you an idea of how much you need to add under the butt assembly, to bring it up to "normal".

A wooden spacer ought to be easier, no?

[GlennC]

Glenn,

there is a broken 1413 stock in my club locker. If you would like, I'll measure the butt tonight, to give you an idea of how much you need to add under the butt assembly, to bring it up to "normal".

A wooden spacer ought to be easier, no?

Tim, I'd appreciate that measurement very much thanks. Wood would be much easier, and I'm an advanced woodworker, but I've not yet devised a solution that makes me happy. I may yet go with wood, but the aesthetics keep leading me to aluminum (or aluminium, if you prefer).

Thanks in advance for the measurement.

Glenn